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  • Organic Chemistry  (1,409)
  • Ecology
  • Industrial Chemistry
  • 1980-1984  (1,434)
  • 1935-1939
  • 1982  (703)
  • 1981  (731)
Collection
Keywords
Publisher
Years
  • 1980-1984  (1,434)
  • 1935-1939
Year
  • 1
    Electronic Resource
    Electronic Resource
    Ecological planning: A review (1981)
    Springer
    Environmental management 5 (1981), S. 495-505 
    Details
    ISSN: 1432-1009
    Keywords: Suitability analysis ; Land-use assessment ; Ecology ; Planning ; Human ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Beginning with the passage of the National Environmental Policy Act in 1969, the federal government of the United States has enacted numerous pieces of legislation intended to protect or conserve the environment. Other national governments have also enacted environmental legislation during the past two decades. State and local governments have also adopted policies concerned with environmental planning and management. Multiple laws and overlapping governmental agency responsibilities have confused development and resource management efforts. A comprehensive methodology that integrates the legal mandates and the agency missions into a common and unified framework is needed. Ecological planning offers such a method. Application of the method allows planners and resource managers to better understand the nature and character of the land and/or resource and therefore make better decisions about its appropriate use or management. The steps taken in an ecological planning process—1) goal setting, 2) inventory and analysis of data, 3) suitability analysis, 4) developing alternatives, 5) implementation, 6) administration, and 7) evaluation—are outlined and explained. Hand-drawn overlays and computer programs as techniques for handling ecological planning information are compared. Observations and suggestions for further research are offered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01866722
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  • 2
    Electronic Resource
    Electronic Resource
    Photosynthetic metabolism in the cyanophytaOscillatoria rubescens D.C. (1982)
    Springer
    Archives of microbiology 131 (1982), S. 107-111 
    Details
    ISSN: 1432-072X
    Keywords: Cyanophyta ; Cyanobacteria ; Oscillatoria rubescens ; Photosynthetic pathways ; Photosynthetic enzymes ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Short term14C labelling experiments and enzymatic activities related to primary pathways of photosynthesis have been studied in the cyanophytaOscillatoria rubescens D.C. from axenic cyclostat cultures. Responses of samples from cultures with different amounts of nitrogen are presented and compared. Variations in photosynthetic pigments are used to quantify the degree of nitrogen starvation at different levels. PEPcarboxylase activity remains low and is not affected by nitrogen starvation. RuBPcarboxylase activity is lowered to nearly two thirds of its normal metabolic rate by starvation but PEPcarboxykinase and aspartate aminotransferase activities are significantly higher in this case. Malate dehydrogenase is slightly altered and malic enzyme is never active. Starved algae replaced in fresh complete media fix rapidly14C in nitrogen compounds such as amino acids. Results are discussed in regard to both physiological and ecological characteristics ofO. rubescens. PEPcarboxykinase can play a role in making efficient use of HCO 3 - .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053990
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  • 3
    Electronic Resource
    Electronic Resource
    On optimal intrinsic growth rates for populations in periodically changing environments (1981)
    Springer
    Journal of mathematical biology 12 (1981), S. 343-354 
    Details
    ISSN: 1432-1416
    Keywords: Ecology ; Periodic differential equations ; Optimization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Summary The theory developed here applies to populations whose size x obeys a differential equation, $$\dot x = r(t)xF(x,t)$$ in which r and F are both periodic in t with period p. It is assumed that the function r, which measures a population's intrinsic rate of growth or intrinsic rate of adjustment to environmental change, is measurable and bounded with a positive lower bound. It is further assumed that the function F, which is determined by the density-dependent environmental influences on growth, is such that there is a closed interval J, with a positive lower bound, in which there lies, for each t, a number K(t) for which $$F(K(t),t) = 0$$ and, as functions on J × ℝ, F is continuous, while ∂F/∂x is continuous, negative, and bounded. Because x(t) = 0, 〉 0, or 〈 0 in accord with whether K(t) = x(t), K(t) 〉 x(t), or K(t) 〈 x(t), the number K(t) is called the “carrying capacity of the environment at time t”. The assumptions about F imply that the number K(t) is unique for each t, depends continuously and periodically on t with period P, and hence attains its extrema, K min and K max. It is, moreover, easily shown that the differential equation for x has precisely one solution x * which has its values in J and is bounded for all t in ℝ; this solution is of period p, is asymptotically stable with all of J in its domain of attraction, and is such that its minimum and maximum values, x min * and x max * , obey $$K_{min} \leqslant x_{min}^* \leqslant x_{max}^* \leqslant K_{max}^* .$$ The following question is discussed: If the function F is given, and the function r can be chosen, which choices of r come close to maximizing, x min * ? The results obtained yield a procedure for constructing, for each F and each ɛ 〉 0, a function r such that x min * 〉 K max − ɛ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276921
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  • 4
    Electronic Resource
    Electronic Resource
    Fagus silvatica L. und das aceri-fagetum an der alpinen Waldgrenze in Mitteleuropäischen gebirgen (1981)
    Springer
    Plant ecology 44 (1981), S. 13-24 
    Details
    ISSN: 1573-5052
    Keywords: Aceri-Fagetum ; Alpine timberline ; Dynamics of stands ; Ecology ; Fagus silvatica ; Morphogenesis ; Polycormons ; Vegetative regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the Central Europaean mountain ranges, the alpine timberline is usually formed by Picea abies or by other conifers (Larix decidua, Pinus mugo, Pinus cembra). Unlike in the East Europaean mountains, the Balkan Peninsula, the Europaean Mediterranean and Les Vosges, Fagus silvatica occurs sporadically on the alpine timberline in this area where it forms very specific woods. This type of the alpine timberline is bound to the association Aceri-Fagetum (Bartsch 1940, Moor 1952). This association is found on the highest sites of the Fagion alliance in the subalpine vegetation zone. Within this zone, the association is bound to localities with heavy snowfall and a submaritime climat. It occupies larger areas in the Swiss Jura and in Les Vosges. In other Central Europaean mountains (the Alps, Schwarzwald, Krkonoše etc.) it occus in isolated areas only. Many trunk deformations and bush forms are found with Fagus on a large scale in the snow impacted localities (steep slopes, periphery of corries, avalanche slopes etc.). Crawling and sliding snow causes these growth deformations in the Fagus seedlings since their first year. The general increase of the vegetative propagation is a remarkable and exceptional response of Fagus in adapting to these extreme growth conditions. Under alpine timberline conditions, the generative propagation is very limited. The vegetative shoots with adventitious root systems are formed mainly from branches layering in the humus. The typical monocormonal tree-form of Fagus from lower altitudes turns in this way into a polycormon. From an evolutionary point of view, it is a suitable substitution; but from the ecological viewpoint, however, it is a sturdy growth form. In its typical form, the polycormon is formed by a number of vegetative shoots, which may be deformed but are very elastic and resistent. The number of shoots in a polycormon varies from 3–5 below, and up to 40–50 at and above the timberline. They are formed by shoots of a number of filial successions. The decay of a polycormon results from decreasing vitality of single shoots or, very often, it is caused by the impact of snow and ice. Considering, however, the fact that single shoots have a sufficient adventitious root system and are thus physiologically independent, the dying of the other shoots does not mean a danger for the existence of the remaining part of the polycormon. The age of a polycormon as a whole is difficult to determine. Fagus polycormons can be considered as a typical growthform of the highest sites of the association Aceri-Fagetum. No other tree species is able to form close stands under these conditions. This phenomenon is of primary importance for the existence of this plant community. The unusual character of the structure and dynamics of the highest Aceri-Fagetum stands gives rise to a special type of the alpine timberline which should be understood not as a ‘line’ but as a transitional zone between the closed stands and the hon-wooded plant communities of the subalpine vegetation zone. The dynamic succession of the Fagus polycormons guarantees the stability of the Fagus stands forming the alpine timberline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119797
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamics ofOstrya carpinifolia woods in the Southern Alps (N-Italy) (1982)
    Springer
    Plant ecology 48 (1982), S. 123-131 
    Details
    ISSN: 1573-5052
    Keywords: Ecology ; Fringe communities ; Numerical classification ; Ostrya carpinifolia woods ; Phytogeographic elements ; Phytosociology ; Southern Alps (N-Italy) ; Vegetation dynamics ; Wood edge communities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forest regeneration in the vegetation complex of the submontane belt in the Southern Alps involves the active participation ofOstrya carpinifolia woods and their wood edge communities. The corresponding syndynamical processes are described by employing phytosociological, phytogeographical and ecological methods. It is concluded that: (i) The communities of the grassland-wood transition are of major importance in the successional developments in this man-made vegetation complex. (ii) Many species occurring in the region of the deciduous forests of Eurasia find their refuge in such transitional communities and are supposed to play an important part in the succession. (iii) Ostrya carpinifolia is considered as an early successional tree species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00726880
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  • 6
    Electronic Resource
    Electronic Resource
    Some observations on the ecology, metal uptake and nickel tolerance of Alyssum serpyllifolium subspecies from the Iberian peninsula (1981)
    Springer
    Plant ecology 45 (1981), S. 183-188 
    Details
    ISSN: 1573-5052
    Keywords: Alyssum serpyllifolium subspecies ; Nickel accumulation ; Nickel tolerance ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments were carried out on the tolerance to, and uptake of, nickel by three iberian subspecies of Alyssum serpylliforium Desf. Two of these subspecies, the serpentine-endemic ssp. lusitanicum from Bragança, Portugal and ssp. malacitanum from Málaga, Spain, are hyperaccumulators (〉 1000 μg/g in dried material) of nickel. Their possible ancestor, ssp. serpyllifolium (from Granada, Spain) was a non-accumulator of this element. Seeds of the two serpentine-endemics germinated extensively in nickel concentrations up to 12 000 μg/g (1.2%) whereas ssp. serpyllifolium only germinated in nickel concentrations below 60 μg/ml. Tolerance tests involving measurement of new root lengths of excised seedlings placed in varying nickel concentrations, again showed much greater tolerance of the two serpentinophytes. In both series of experiments, the order of tolerance was: ssp. lusitanicum 〉 ssp. malacitanum 〉 ssp. serpyllifolium. In pot trials involving seedlings of ssp. malacitanum grown in mixtures containing varying amounts of calcium, magnesium, and nickel, the most important finding was that plants will tolerate higher nickel contents in the soil when excess calcium is added. This is achieved by lowering the uptake of nickel. There appeared to be some concomitant reduction in calcium uptake in the presence of nickel, and some increase in uptake of magnesium. The resultant lower calcium/magnesium ratio in the plant, though not symptomatic of a favourable condition for colonization of serpentine soils, probably results from a mechanism which renders nickel innocuous to the plant at the expense of calcium uptake. It is suggested that the physiological characters of ssp. lusitanicum and ssp malacitanum are sufficiently different to support arguments for promoting the latter to full specific rank as has now been done for ssp. lusitanicum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00054673
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  • 7
    Electronic Resource
    Electronic Resource
    Factors affecting growth and nodulation ofHippophaë rhamnoides L. ssp.Rhamnoides in soils from two successional stages of dune formation (1981)
    Springer
    Plant and soil 63 (1981), S. 317-331 
    Details
    ISSN: 1573-5036
    Keywords: Actinorhizas ; Ecology ; Gamma irradiation ; Hippophaë rhamnoides ; Longidorus ; Nematode ; Nodulation ; Root nodules ; Soil sterilization ; Succession
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary To explain the decline of Hippophaë scrub in the vegetation succession in the dunes of The Netherlands, the growth and nodulation of Hippophaë plants grown in pots, using soil from an early stage (site AH) and a post-optimum stage (site HP), were investigated. In HP-soil nodulation, yield, and the nitrogen and phosphorus content of test plants were always lower and the number of necrotic nodules and the dry matter content were always higher than in AH-soil, even after inoculation with crushed nodules and the addition of a nutrient solution. Plants in HP-soil also had darker roots, less root hairs, a higher number of short lateral roots and a higher percentage of dead roots than those in AH-soil. These characteristics of adverse growth conditions disappeared upon ignition or gamma-irradiation of HP-soil. Possible explanations of these results are discussed. The degeneration of Hippophaë scrub cannot be ascribed to the age of the plants, the absence of sufficient infective endophyte particles or to abiotic factors such as unfavourable physical (particle size) or chemical soil conditions but is caused by biotic factors. No indications were obtained that plant-pathogenic fungi and bacteria are involved. HP-soil in contrast to AH-soil, however, contained large numbers of the nematodeLongidorus sp., a species known to cause root deformations. The conclusion was that this nematode is one of the biotic factors involved in the degeneration of the Hippophaë scrub. This degeneration is due to a restriction of the root system resulting in a low phosphate uptake, a low nodulation capacity and, as a consequence, a low nitrogen content. The results demonstrate that biotic soil factors are important in influencing succession in higher plant communities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02370033
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  • 8
    Electronic Resource
    Electronic Resource
    Frankia growth and activity as influenced by water potential (1982)
    Springer
    Plant and soil 69 (1982), S. 293-297 
    Details
    ISSN: 1573-5036
    Keywords: Ecology ; Frankia ; Nitrogen fixation ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth responses of Frankia isolates to decreasing water potential were monitored in systems where potentials were controlled by KCl, NaCl and Polyethylene glycol. The highest potential tested was −2 bar (basal medium). The general pattern emerging was that isolates fromAlnus glutinosa, A. viridis andComptonia peregrina showed declining growth at potentials below −2 to −5 bar. AMyrica gale isolate showed declining growth with decreasing potential. All isolates were more sensitive to decreases in potential in a matric controlled than an osmotic controlled system. They all showed approximately 50 percent growth reduction at −5 to −8 bar, and meagre growth at −16 bar after 35 days. The Comptonia isolate was the most vigorous at low potentials. Nitrogen fixation ability was monitored for two isolates. Highest specific activities were observed between −3 and −5 bar for the Myrica isolate and between −5 and −7.5 bar for theA. glutinosa isolate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02374525
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of crop rotation and fertilization on catalase activity in a soil of the southeastern United States (1982)
    Springer
    Plant and soil 69 (1982), S. 97-104 
    Details
    ISSN: 1573-5036
    Keywords: Catalase ; Ecology ; Fertilizers ; H2O2∶H2O2 oxidoreductase ; Rhizosphere effects ; Soil enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Catalase activity of a loamy sand under a 3-year crop rotation in the southeastern U.S.A. was monitored. Corn (Zea mays L.), cotton (Gossypium hirsutum L.), and soybean [Glycine max (L.) Merr.] were the summer crops in the rotation. Winter wheat (Triticum aestivum L.) was planted after corn, and soybean was followed by a winter fallow period. Cotton was followed by a mixture of common vetch (Vicia sativa L.) and crimson clover (Trifolium incarnatum Gibelli & Belli) which was eventually plow-incorporated as a green manure. Highest mean catalase activities were recorded in soil under the wheat, soybean, and winter legume crops; lowest activities were found in soil bearing corn and cotton, and during the winter fallow period. The fertilization regime influenced soil catalase activity independently of the crop. Soil deficient in any of the major elements showed low enzyme activity. Highest activity was found in soil fertilized with P and K, and with N supplied by a winter legume crop. Addition of supplementary mineral nitrogen to this regime reduced catalase activity. Elimination of the winter legume crop from an otherwise complete fertilization regime resulted in a drastic reduction in enzyme activity. In soil receiving a complete fertilization regime there was a close correlation between soil catalase and xylanase activities. A similar correlation between these two enzymes was not found in soil receiving incomplete fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02185708
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  • 10
    Electronic Resource
    Electronic Resource
    Production ecology in the Northern Baltic (1981)
    Springer
    Hydrobiologia 76 (1981), S. 87-96 
    Details
    ISSN: 1573-5117
    Keywords: Ecology ; production ; Gulf of Bothnia ; pelagial ; benthos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Production biology in the Bothnian Bay is discussed and compared to that of the southern parts of the Baltic. Severe ice-conditions, low water temperatures in spring and early summer and a pronounced water-colouring cause a delay of the spring development of phytoplankton and a low annual production in the Bothnian Bay. This delay makes possible a higher efficiency of the pelagic system as the zooplankton fauna can develop in harmony with the food resources. The downward transport of energy and matter to the bottom communities from an efficient pelagial should be small and temporally unpredictable, which is thought to be an adequate explanation of the observed very low benthic fauna biomasses in the Bothnian Bay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014038
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  • 11
    Electronic Resource
    Electronic Resource
    Reproductive tactics of the Asian cichlids of the genusEtroplus in Sri Lanka (1981)
    Springer
    Environmental biology of fishes 6 (1981), S. 95-103 
    Details
    ISSN: 1573-5133
    Keywords: Behavior ; Ecology ; Parental care ; Reproductive cycles ; Colonial nesting ; Etroplus maculatus ; Etroplus suratensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The Asian cichlids,Etroplus maculatus (the orange chromide) and E. suratensis (the green chromide) in Sri Lanka reproduce twice during the year when water conditions are favorable for nest construction and maintaining visual contact with offspring. These are the drier premonsoonal and monsoonal seasons when water turbidity decreased and salinity increased. When breeding in isolation orange chromide pairs selected dense vegetation where nests were camouflaged. During the peak breeding cycle (July) orange chromide pairs selected sparse vegetation for nesting as a compromise between survival of young and availability of adult food. These areas were also occupied by foraging non-breeding conspecifics which increased the threat of cannibalism of offspring. Under these pressures most orange chromides nested in colonies which helped decrease both actual and attempted cannibalism. The sympatric green chromide does not forage during nesting and nest site selection was determined mainly by factors favoring offspring survival. Biparental care is exhibited by both species. One member of an orange chromide pair stands guard over offspring while the other leaves the territory to forage — their roles are reversed every few minutes. The total parental investment is equivalent to the full investment of a single parent. Monogamy appears to be maintained by their metabolic constraints. In the green chromide both parents are vigilant over offspring and neither forages thus spending twice as much time in parental investment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001803
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  • 12
    Electronic Resource
    Electronic Resource
    Fluctuations in the muskellunge (Esox masquinongy Mitchill) population of Chautauqua Lake, New York (1981)
    Springer
    Environmental biology of fishes 6 (1981), S. 207-211 
    Details
    ISSN: 1573-5133
    Keywords: Fish ; Ecology ; Population density ; Exploitation ; Tagging ; Catch per effort
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Population and exploitation estimates were made from angler recaptures of Chautauqua Lake muskellunge,Esox masquinongy Mitchill. Fish were tagged during Conservation Department studies in 1941–1946, 1961–1965 and 1976–1978. Population estimates of adult fish ranged from one to seven fish per hectare and angler exploitation rates of tagged fish fluctuated from 3.8% to 14.1%. Relative catch indicators suggest a major decline in the lake's muskellunge population during the last decade. Overexploitation, habitat alteration and interspecific competition with recently introduced fish species were cited as probable causes of the decline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002785
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  • 13
    Electronic Resource
    Electronic Resource
    The lack of changes in nocturnal estuarine fish assemblages between new and full moon phases in Serpentine Creek, Queensland (1981)
    Springer
    Environmental biology of fishes 6 (1981), S. 213-218 
    Details
    ISSN: 1573-5133
    Keywords: Australia ; Communities ; Cycles ; Diversity ; Ecology ; Estuary ; Lunar periodicity ; Migration ; Sub-tropics ; Tides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis A series of 10 sites were sampled at new and full moon phases in a vertically homogenous estuary, Serpentine Creek, Queensland, Australia. Forty-five species (14,518 individuals) were caught and analysed using standardized Shannon & Gleason diversity indices, and total number of species and individuals. The coefficients of variation for these values were greater for times than for sites. There were no significant differences between 14 pairs of new and full moon phases fort,t,t, andt, or between mean number of individuals for the 16 most abundant species. If significant variations do exist within months, then experiments should be done between spring and neap tides as this study found no differences between the spring tides associated with new and full moon phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002786
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  • 14
    Electronic Resource
    Electronic Resource
    Progress report on the eel expedition of R.V. ‘Anton Dohrn’ and R.V. ‘Friedrich Heincke’ to the Sargasso Sea 1979 (1981)
    Springer
    Environmental biology of fishes 6 (1981), S. 371-375 
    Details
    ISSN: 1573-5133
    Keywords: Anguilliformes ; Anguillidae ; Leptocephalus ; Fish larvae ; Horizontal distribution ; Vertical distribution ; Spawning area ; Migration ; Ultrasonic tracking ; Hydrography ; Ecology ; North Atlantic ; Anguilla anguilla ; A. rostrata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis This report presents preliminary results of the 1979 Sargasso Sea expedition from February to May 1979. Information is given on horizontal and vertical distribution of eel larvae and adults, adult eel tracking and pelagic trawling. Related matters such as electrophoretic studies on anguilliform larvae, feeding of eel larvae, predation on leptocephali, occurrence of other anguilliform larvae and hydrography are mentioned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00005768
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  • 15
    Electronic Resource
    Electronic Resource
    Thermoregulatory behavior and diel activity of yearling winter flounder, Pseudopleuronectes americanus (Walbaum) (1982)
    Springer
    Environmental biology of fishes 7 (1982), S. 177-180 
    Details
    ISSN: 1573-5133
    Keywords: Temperature ; Behavior ; Ecology ; Fisheries ; Fish ; Marine juveniles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Sixteen yearling winter flounder, tested individually for 3-day periods in electronic shuttleboxes, voluntarily occupied an 8–27°C range of temperature, with a modal final thermal preferendum of 18.5°C (mean 18.7°C, median 19°C, midpoint 17.5°C, s.d. 1.9°C, S k + 0.33). The locomotor activity pattern of the yearling fish in the laboratory was markedly nocturnal, with mean hourly nocturnal activity exceeding mean hourly diurnal activity by a factor of 3.4. Maximum activity occurred at 0300 EST, minimum activity at 1400 EST. While activity generally increased with temperature, a local activity minimum occurred at 18.7°C, coinciding with the 24-hour mean final thermal preferendum. Comparison of these laboratory data with previously published field data suggest that behavioral responses to temperature and light play significant roles in determining age- and size-specific differences in seasonal depth stratification and onshore-offshore distributions in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001789
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  • 16
    Electronic Resource
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    Field observation on death feigning: a unique hunting behavior by the predatory cichlid, Haplochromis livingstoni, of Lake Malawi (1981)
    Springer
    Environmental biology of fishes 6 (1981), S. 361-365 
    Details
    ISSN: 1573-5133
    Keywords: Mimicry ; Shamming death ; Africa ; Fish ; Chafing ; Predation ; Ecology ; Cyrtocara
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Haplochromis (=Cyrtocara) livingstoni, one of the predatory cichlids of the sand community of Lake Malawi, Africa, occurs at a density of 1.3 individuals per hectare. They are territorial, defending areas 15 m wide by 40 m long along the interface of sand andVallisneria weed beds. Individuals use a ‘death feigning’ hunting pattern to capture prey. From a position of lying on their sides semiburied in the sand, these fish attack small cichlids. During four hours of SCUBA observations three successful attacks from this position were seen. After an attack the small cichlids scatter and the predator moves on toward a new aggregation of fish where it again plays dead. Individuals feign death an average of seven times per thirty minutes watch. Death feigning behavior is initiated in two ways. The fish either 1) is stationary with its ventral surface on or close to the sand, and then falls onto its side, or 2) drops from the water colum into `lying on side' position. The initial behavioral actions of the latter method are similar to chafing behavior. But instead of chafing the sand and rising again off the bottom, the fish plows into the sand and remains immobile. These data further add to the evidence that cichlids are remarkably flexible in their feeding behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00005766
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  • 17
    Electronic Resource
    Electronic Resource
    Patterns of abundance variation in reef fishes near an artificial reef at Guam (1982)
    Springer
    Environmental biology of fishes 7 (1982), S. 121-136 
    Details
    ISSN: 1573-5133
    Keywords: Seasonality ; Predator-prey ; Predator interference ; Turnoverrate ; Diversity ; Ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Development of the fish community on a submerged 16 m barge and variation in fish abundance on nearby transects were surveyed twice monthly for twenty months. A steady increase in abundance was observed for certain fishes on the barge, whereas a few species exhibited distinct seasonal variation on both the barge and transects. Most of the seasonal species settled between March and May. Some seasonal species appeared to be site selective in their settlement and consequently settled juveniles were clumped in their distribution. An abundance of preferred topographical features may be why settlement was relatively high at the study site and indirectly why predators became significantly (r3 = 7.67***, N = 37) more abundant at the study area during the months of maximum prey settlement. Concurrent settlement of several species during the same few months may be important because juveniles become an abundant food source to predators during those few months only. Periodic swamping of predators by abundant juvenile prey may improve the chances for individuals of rarer prey species to be overlooked and therefore be succesfully recruited.
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    URL: http://dx.doi.org/10.1007/BF00001782
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    Populations ofRhizobium japonicum associated with the surfaces of soil-grown roots (1981)
    Springer
    Plant and soil 61 (1981), S. 71-80 
    Details
    ISSN: 1573-5036
    Keywords: Ecology ; Fluorescent antibody ; Immunofluorescence ; Rhizobium japonicum ; Rhizosphere ; Root surfaces ; Soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Populations of nativeRhizobium japonicum 123 in the rhizospheres of field and pot grown plants as determined by immunofluorescence were calculated on the basis of root surface area. The density ofR. japonicum 123 on the root fluctuated between a few hundred to over a thousand per square centimeter of root surface. As root volume expanded rapidly, the Rhizobium density fell to less than one hundred per unit area. There was no appreciable effect due to different plant, nitrogen amendment, or addition of another strain ofR. japonicum, on the surface density of the nativeR. japonicum population on roots. Nor did the native population influence the added strain. Direct examination of root surface segments revealed that naturalized rhizobia existed sparsely on root surfaces in the form of short rods. They were observed to be attached sideways or in a polar manner on root hairs, epidermal cells, and at junctions of tap and lateral roots. There was no evidence of specific stimulation of the homologous Rhizobium by the host plant as a prelude to nodulation.
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  • 19
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    Masthead (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981) 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/hlca.19810640101
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  • 20
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    Physico-Chemical Properties of Deuterated Compounds. 5th Communication4th Communication, see[1].. The isotope partition coefficient in cyclohexane hydrogen and cycloheptane/hydrogen mixtures (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 176-179 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The isotope partition coefficient α between cyclohexane, cycloheptane and hydrogen has been determined between 80 and 180° and pressures around 1 atm. The values decrease with increasing deuterium content y of the hydrogen and can be expressed by the simple equation Ina = Δ S/R + (ΔH + δ · y)/RT with an error of ±1%. However it was not possible to achieve good agreement with theoretical calculations using a unique average value for the partition function of the hydrocarbon.
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  • 21
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    Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVI. Kinetics and mechanisms of dediazoniation of p-chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions under nitrogen gasPart XV: s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 513-528 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of reactions of p-chlorobenzenediazonium ions in aqueous buffer solutions (pH 9.0-10.6) under N2 (〈 5 ppb of O2) have been measured between 20 and 50°C. The formation of trans-diazotate is first-order with respect to the concentration of hydroxyl ions and to the equilibrium concentration of diazonium ions, if the diazonium ion⇄cis-diazotate equilibrium is considered as a fast prior equilibrium. This indicates that the p-chlorobenzenediazonium ion, in contrast to all previous investigations with the p-nitrobenzenediazonium ion and benzenediazonium ions carrying similar substituents with a -M effect, rearranges from the cis- to the trans-configuration as diazohydroxide and not as diazotate. The formation of trans-diazotate is catalyzed by carbonate and inhibited by hydrogen carbonate ions; mechanisms of these catalyses are discussed, and the solvent isotope effect KH2O/KD2O measured by an 1H-NMR. technique reported. The kinetics of the dediazoniations can be analyzed as a mixture of two reactions, a relatively fast first reaction, reaction A, which is responsible for about 5% of the total reaction, and a second reaction F. Both are first-order with respect to diazonium ion; reaction A is also first-order in hydroxyl ions. There are some indications that reaction A corresponds to the hydrolysis of the diazonium ion to give eventually amine and nitrite ions. Reaction F shows a complex dependence on hydroxyl ions; it is related to the homolytic dediazoniation.
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  • 22
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    Preferential Solvation of the Sodium Cation in Binary Mixtures of Tetrahydrofuran with Unidentate Nitrogen Ligands (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 547-555 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 23Na-chemical shifts for the NaClO4 solute depend markedly upon the composition of binary solvent mixtures of THF with amines (pyridine, piperidine, pyrrolidine, aniline, propylamine, and isopropylamine). These changes, analyzed in a novel application of the Hill formalism, show equality of the intrinsic equilibrium constant K for the successive steps, upon displacement of THF from sodium coordination by one of these amines. The results, which are entirely consistent with tetracoordination of the sodium cation by these solvents, also indicate proportionality of the K values to the amine chemical shifts.
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  • 23
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    The Reaction of Pyruvic Acid with Amines and Aminoesters Reexamined. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 568-571 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenylglycine esters react with pyruvic acid to give α-methylsuccinic amides 9 instead of the expected Schiff bases 8, analogously to p-anisidine but unlike aniline.
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  • 24
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    Propellanes. LXII. The endo- and exo-adducts of 11-cyano-1,6-methano[10] annulene with 4-methyl-1,2,4-triazoline-3,5-dionePart LXI: see [1].Dedicated to the memory of Professor Frantisek Šorm (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 579-581 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds have been isolated and their structures determined by X-ray crystallography. Their relative stability is discussed in terms of theory and experiment. The endo-adduct is the thermodynamically more stable one.
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  • 25
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    Notizen zur Synthese sulfonierter Derivate von 5,6,7,8-Tetrahydro-1-naphthylamin und 5,6,7,8-Tetrahydro-2-naphthylamin (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 572-578 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Notes on the Synthesis of Sulfonated Derivatives of 5,6,7,8-Tetrahydro-1-naphthylamine and 5,6,7,8-Tetrahydro-2-naphthylamineSulfonation of 5,6,7,8-tetrahydro-1-naphthylamine (1) with sulfuric acid gave a mixture of 1-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (2), 4-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (13) and 4-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (3). The same reaction with 5,6,7,8-tetrahydro-2-naphthylamine (20) yielded 3-amino-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (21); formation of 2-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (16) or of 3-amino-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (24) was not observed. Treatment of 4-bromo-5,6,7,8-tetrahydro-1-naphthylamine (4) or of its 4-chloro analogue 5 with amidosulfuric acid gave 1-amino-4-bromo-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (9) and its 4-chloro analogue 10, respectively, which were dehalogenated to 2. Preparations of 13 and 24 were achieved by sulfonation of 5-nitro-1,2,3,4-tetrahydronaphthalene (14) and 6-nitro-1,2,3,4-tetrahydronaphthalene (22) to 4-nitro-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (15) and 3-nitro-5,6,7,8-tetrahydronaphthalene-1-sulfonic acid (23), respectively, followed by Béchamp reductions. The sulfonic acid 13 was also obtained by hydrogenolysis of 4-amino-1-bromo-5,6,7,8-tetrahydronaphthalene-2-sulfonic acid (11) or of its 1-chloro analogue 12; compounds 11 and 12 were synthesized from N-(4-bromo-5,6,7,8-tetrahydro-1-naphthyl)acetamide (7) and from its 4-chloro analogue 8, respectively, by sulfonation with oleum and subsequent hydrolysis. By ‘baking’ the hydrogensulfate salt of 1 or 20 compounds 3 and 21 were obtained, respectively. Synthesis of 16 was achieved by sulfur dioxide treatment of the diazonium chloride derived from 2-nitro-5,6,7,8-tetrahydro-1-naphthylamine (17) giving 2-nitro-5,6,7,8-tetrahydronaphthalene-1-sulfonyl chloride (18), followed by hydrolysis of 18 to the corresponding sulfonic acid 19 and final reduction.
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    A Note on Stereochemical Observations of the Deprotonation of Ethyl 2-Alkenoates (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1023-1025 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deprotonation of ethyl (E)-2-alkenoates 1, 3 and 4 yields after protonation the double bond migrated (3 Z)-isomers 5, 7 and 9 as major products. In contrast, deprotonation and reprotonation of ethyl (Z)-2-pentenoate (2) gives the (3 E)-isomer 6 exclusively. These findings are explained by reaction paths starting from different ester conformations.
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  • 27
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    Ein neuer Reaktionsweg zu 1, 3-Dicarbonylderivaten. Modelluntersuchungen am A/B-Teil von 3-Oxo-5α-steroiden (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1026-1031 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A New Route to 1, 3-Dicarbonyl Derivatives, Model Investigations on the A/B-Part of-3-Oxo-5α-steroidsStarting from 1 the 1, 3-dicarbonyl compounds 4a-d were synthetized via the enynes 2a-e and the relatively unstable epoxides 3a-d. The latter were reacted with 95% formic acid to gave 4a-d; small amounts of the furane derivatives 5a-c were identified as by-products in this last step. In the presence of catalytic amounts of HgSO4 the epoxides 3a-c yielded with 95% formic acid the furanes 5a-c, but no detectable amounts of 4a-c.
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    Some Observations Concerning 1H-NMR. Spectra of 5-hydroxy- and 5-acetoxy-steroid compounds (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1032-1039 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It was found that analysis of the 1H-NMR. signals (at 360 (preferably) and/or 100 MHz) of the protons at C (4) and of the equatorial α-proton at C (6), particularly when these are located in the 2-3 ppm region and therefore convenient for detection and identification, may be of valuable aid in the structural and configurational characterization of 5-hydroxy- and 5-acetoxy-steroids (unsubstituted or containing a hydroxy or acyloxy substituent at C (3)).
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    Heterodiamantane und strukturell verwandte Verbindungen. III.Teil II, vgl. [1].. Pentacyclische diäther der C11-reihe. 5, 13-Dioxapentacyclo-[6.5.0.02,6.03,12.04,9]tridecan, 4, 13-dioxapentacyclo [6.4.1.02,7.03,10.05,9]tridecan und 3, 10-dioxapentacyclo [7.3.1.02,7.04,12.06,11]tridecan (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 996-1022 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterodiamantanes and Structurally Related Compounds. Part III. The Pentacyclic C11-Diethers 5, 13-Dioxapentacyclo [6.5.0.02,6.03,12.04,9]tridecane, 4, 13-Dioxapentacyclo [6.4.1.02,7.03,10.05,9]tridecane, and 3, 10-Dioxapentacyclo [7.3.1.02,7.04,12.06,11]tridecaneIn connection with the studies on heterodiamantanes and structurally related compounds the three novel pentacyclic diethers 3-5 were prepared starting from the cyclopentadienone dimer 6. All four compounds have as common features a central carbocyclic 6-membered ring with four axial alkyl substituents and two oxygen functions in 1, 4 position. The required eleventh C-atom was introduced by dichlorocarbene addition either to 6 ( → 7) (Scheme 2) or to 29 ( → 28) (Scheme 4).Diether 3 was obtained by reduction of 26 (Scheme 2), a suitable precursor prepared either by intramolecular addition (24 → 26; Scheme 2) or substitution (30 → 26, 31 → 26; Scheme 4), as well as by direct substitution (44 → 3, 42 → 3; Scheme 5). Diether 4 was the product of a direct substitution (39 → 4, 36 → 4; Scheme 5). The synthesis of diether 5 was achieved from the addition product 51 (resulting from the alcohols 47 and 48; Scheme 6).Diether 4 is the thermodynamically least stable of the three diethers 3-5. It was easily isomerized to 5 on treatment with concentrated sulfuric acid in benzene whereas 3 and 5 remained unchanged under these conditions.
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    Cryptates Sphériques. Synthèse et Complexes d'Inclusion de Ligands Macrotricycliques SphériquesDédié à la mémoire du Professeur Frantisek Šorm (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1040-1057 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Spherical Cryptates. Synthesis and Inclusion-Complexes of Spherical Macrotricyclic LigandsA general strategy for the synthesis of spherical macrotricyclic ligands has been developed. Four spherical cryptands, SC-24, SC-25, SC-26 and SC-27 have been obtained by this route. The synthesis and cation-complexing properties of these compounds are described in detail. Stability constants and cation exchange rates of the spherical cryptates obtained with alkali and alkaline-earth cations have been determined. Highly stable complexes are formed by SC-24; the Rb+ and Cs+ cryptates of SC-24 are the most stable complexes of these cations known to date. The size of the intramolecular cavity affects the complexation selectivity. The cation exchange rates are very slow, and the corresponding free energies of activation are even larger than, for macrobicyclic cryptates of similar stability. Both the high complex stabilities and the high activation energies required for cation exchange indicate a marked ‘spherical cryptate effect’ resulting from the highly connected nature of the molecular architecture of spherical macrotricyclic ligands.
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    Rates of Proton Abstraction from Conjugated Dienes in the Gas Phase (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1058-1062 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of proton transfer from 2, 4-hexadiene, 1, 3-cycloheptadiene, cyclopentadiene and acetone to t-butoxide have been measured in the gas phase using pulsed-ion-cyclotron-resonance spectroscopy. The rate constants are (units of 10-10 cm3 molecule-1 s-1): 2.7 ± 0.4, 3.8 ± 0.4, 6.1 ± 0.7 and 10.8 ± 1.5, respectively. These results are analyzed in terms of the properties of the encounter complex and reaction transition states. The reaction profile for t-butoxide + cyclopentadiene is modeled using RRKM theory and an estimate for the central barrier height is obtained.
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    Reaktionen von 2- und 3-phenylsubstituierten Alkylakyliden-iminium-Ionen in der Gasphase. 5. Mitteilung über stossinduzierte Fragmentierungen von felddesorbierten Kationen4. Mitt. s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1083-1091 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of 2- and 3-Phenyl Substituted Alkylalkylidene Iminium Ions in the Gas PhaseThe collision-induced fragmentations of 2- and 3-phenyl substituted alkylalkylidene iminium ions are reported. Besides the homolytic cleavage of the azaallyl bond a nucleophilic attack of the unsubstituted phenyl group at the iminium function is observed in the gas phase, yielding carbonium ions such as cyclopropanspirobenzenium (3), indanylium (10) and indenylium ions (11).
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    Carotenoids and Related Compounds. Part 36.Part 35: [1].. Further syntheses of zeaxanthin and rhodoxanthinDedicated to Prof. Conrad Hans Eugster on the occasion of his 60th birthday (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1092-1097 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modification of a previously reported synthesis of zeaxanthin (1), and routes to both zeaxanthin and rhodoxanthin (2) from α-ionone, are described.
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    The Influence of Molecular Host Lattices on Electronic Properties of Orbitally (Near-) Degenerate Transition Metal ComplexesHerrn Prof. Dr. Conrad Hans Eugster zum 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1063-1082 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition metal complexes often have low-lying excited electronic states and, as a consequence, tend to be electronically labile, i.e., their electronic properties exhibit pronounced sensitivity to external perturbations. Often drastic changes in various spectroscopic properties indicating substantial electronic rearrangements can be induced be relatively weak intermolecular forces as provided by nonpolar solvents or solid molecular host lattices. This behaviour can be explained by crossing of potential surfaces in the vicinity of the absolute minimum. Many physical properties of a given orbitally (near-) degenerate system depend strongly on the relative magnitude of some characteristic parameters determining the shape of the ground Born-Oppenheimer potential surface(s), e.g. barrier height versus zero-point energy, distance between minima versus zero-point amplitude, energy difference between minima, etc. Typical examples are systems exhibiting Jahn-Teller activity, spin-crossover, mixed valence, exchange coupling and other types of electronic near-degeneracies. In paramagnetic systems changes in the electronic wavefunction can be most conveniently detected and analyzed by using EPR. spectroscopy.In paramagnetic sandwich complexes we studied two types of orbital degeneracies: Jahn-Teller degeneracies (d7-systems such as Co (cp)2, Ni(cp)2+ and Fe (cp) (bz), low-spin d5-systems such as Mn (cp)2) and low-spin/high-spin equilibria (d5-systems such as Mn (cp)2). By diluting these complexes and ring-substituted derivatives in a large variety of diamagnetic host systems we have been able to control the 6A/2E equilibrium of Mn (cp)2 by influencing the metal-to-ring distance and by changing the degree of ring alkylation; similarly we have been able to vary the relative weights of the two electronic states contributing to the two-fold degenerate electronic ground state of d5- and d7-systems to a large degree by variation of the local asymmetric fields offered by the lattice sites of the host systems.For comparison the electronic ground state properties of octahedral Cu(II) complexes with CuN6 CuO6 chromophores, of V (CO)6 and tetrahedral VCl4 were also studied by EPR. between 4K and room temperature in several host systems. Characteristic differences in the details of the temperature and host dependence of the EPR. spectra in all these electronically labile systems can be explained in terms of differences in the vibronic coupling type (E ⊗ e vs. T ⊗ e, t), the strength of linear and/or quadratic JT-coupling and the effects produced by spin-orbit coupling.
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    Synthese und Struktur porphinoider Nickel-Komplexe mit axial orientierten Seitenketten10. Mitt. über «Synthese und Reaktionen porphinoider Metallkomplexe». 9. Mitt. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1098-1112 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis and Structure of Porphine-type Nickel Complexes Containing Axially Oriented SidechainsThe structure of (±)-[1, 11-dimethoxy-10 H-HDP (2-)]nickel (3), the product of the thermodynamically controlled addition of methanol to [6 H-HDP]nickel-bis-(tetrafluoroborate) (1), was determined by X-ray analysis. The two methoxy groups in 3 are cis-oriented. The syntheses and spectroscopic properties of [1, 11-diethoxy-10 H-HDP (2-)]nickel (5), [1, 11-dineopentyloxy-10 H-HDP (2-)]nickel (6) as well as the bridged complexes [1, 11-pentamethylenedioxy-10 H-HDP (2-)]nickel (4) and [1, 11-(E)-2,3-(dimethyl-2-butenylenedioxy)-10 H-HDP (2-)]nickel (7) are described. Reaction of 1 with bromide ions or 4-methylpyridine leads to the formation of the corresponding hexacoordinated, paramagnetic complexes dibromo [6 H-HDP]-nickel (II) (8) and bis (4-methylpyridine)[6 H-HDP]nickel-bis (tetrafluoroborate) (9).
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    Synthesis of Reactive Intermediates for Natural Cyclopentane Derivatives from (-)-Quinic Acid: Preparation of 11α-hydroxy-13-oxaprostanoic acidDedicated to the memory of Prof. Frantisek Sorm (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1140-1144 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe a flexible, stereocontrolled synthesis of enantiomerically pure substituted cyclopentenes and cyclopentanes - including 11α-hydroxy-13-oxaprostanoic acid 20 - (-)-quinic acid via an acyclic precursor 6 by an intramolecular aldolisation-dehydration reaction.
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    Chiral 1, 4-Benzodiazepin-2-one, template for enantioselective synthesis of α-amino acids and their α-deuterio congeners. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1145-1149 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Absolute conformation of 7-chloro-5-phenyl-1-[(S)-α-phenylethyl]-1, 3-dihydro-2H-1, 4-benzodiazepin-2-one (1c) in crystal, and its inversion rate in solution were determined, enabling prognosis of direction of asymmetric induction during C(3)-alkylation.
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    Anwendung der α-Alkinon-Cyclisierung: Synthese von rac-ModhephenVorgetragen von M. Karpf an der Versammlung der Schweizerischen Chemischen Gesellschaft am 17. Oktober 1980 in Bern; als vorläufige Mitteilung erschienen in [1]. Anmerkung bei der Korrektur: Vor kurzem sind zwei weitere Synthesen von Modhephen veröffentlicht worden: (a) A.B. Smith, III & P.J. Jerris, J. Am. Chem. Soc. 103, 194 (1981); (b) H. Schostarez & L.A. Paquette, J. Am. Chem. Soc. 103, 722 (1981).Herrn Prof. Dr. Conrad Hans Eugster zu seinem 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1123-1133 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Application of the α-Alkynone Cyclization: Synthesis of rac-Modhephenerac-Modhephene 1, the first sesquiterpene with a propellane C-skeleton and its epimer rac-epi-modhephene 27, were synthesized starting from bicyclo[3.3.0]oct-1(5)-en-2-one (2). The key step in the construction of the [3.3.3]-propellane system is an application of the α-alkynone cyclization, namely 3 → 4 and 11 → 14. The preferred formation of the propellanes 4 and 14 in this step shows that the insertion of the postulated alkylidene carbene intermediate into tertiary C,H-bonds outweighs the one into the secondary ring-C,H-bonds leading to 12/13 and 15/16, respectively. The two starting materials for the α-alkynone cyclization, 3 and 11, were prepared from 2 by the reactions shown in Scheme 3. The further elaboration and separation of the cyclization products 4 and 14 to rac-modhephene 1 and its epimer 27 are outlined in Scheme 5.
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    Studies on the Conversions of Diols and Cyclic Ethers. Part 48Part 47: [1].. Dehydration of alcohols and diols on the action of dimethylsulfoxide (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 389-398 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The transformations of 13 alcohols and 13 diols in the presence of a small amount dimethylsulfoxide (1/16 mol) were studied. Relationships were found between the type of the hydroxy compound and the selectivity of the transformation, and conclusions were drawn regarding the transformation mechanism. The ether formation observed with certain alcohols proceeds via a carbenium cation. The reaction conditions applied were found suitable for inducing water elimination from the ditertiary 1,2- and 1,3-diols (pinacol rearrangement, 1,2-elimination). From the 1,4- and 1,5-diols the corresponding oxacycloalkanes can be obtained in good yield. Cyclodehydration occurs by intramolecular nucleophilic substitution, via a concerted mechanism. The effect of DMSO is exerted directly, and protoncatalysis occurs simultaneously.
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    Un nouvel exemple de nucléoside à sucre ramifié insaturé: la désoxy-3′-méthylidène-3′-adénosine (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 425-429 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Novel Example of Unsaturated Branched-chain Sugar Nucleoside: 3′-Deoxy-3′-methylidene-adenosineStarting from 5-O-benzoyl-3-C-methylidene-3-deoxy-1,2-O-isopropylidene-α-D-erythro-pentofuranose (11) the title compound 8 has been prepared. Its α-anomer (9) and the acyclic sugar nucleoside 10 have been obtained as by-products. Adenosine deaminase slowly deaminated 8, 9 being not affected. Compound 8 exhibited no antiviral activity, whereas one of its saturated analogues (13) inhibited the multiplication of the herpes-1 (HF) virus.
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  • 41
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    Natural Occurrence of Enantiomeric and meso-Astaxanthin. 5. Ex wild salmon (Salmo salar and Oncorhynchus) (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 449-457 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The configurational isomers of astaxanthin (3,3′-dihydroxy-β,β-carotene-4,4′-dione) from the flesh of salmon (Salmo salar and Oncorhynchus) caught at different places in Europe and Canada were isolated and analyzed as (-)-camphanic acid diesters by means of HPLC. The biological variation in the composition of the configurational isomers in seven fish was surprisingly similar: 78 to 85% of (3S, 3′S)-astaxanthin, 12 to 17% (3R, 3′R)-astaxanthin and 2 to 6% meso-astaxanthin.
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    Computer Assisted Structural Interpretation of Mass Spectral DataPart XXXVI of the series ‘Application of Artificial Intelligence for Chemical Inference’. For part XXXV see [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 458-470 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An interactive system of programs has been developed to assist in structure elucidation based on mass spectral data. The program relies on algorithms for generating all the structural isomers that constitute alternative explanations of the observed data and it associates relative plausibility values with the different isomers. The structure assembly part of the program allows for the use of overlapping substructural components, such as substructures inferred from the appearance of particular ion patterns in the spectrum of an unknown compound. Mass spectrum interpretation procedures used with this structure assembly process could exploit any form of spectrum-substructure correlation scheme. In this work, the emphasis has been on the use of detailed and class specific spectrum-substructure correlations. Applications of the program are illustrated by means of an example analysis of the mass spectra of a variety of marine sterols.
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    Selektive Umfunktionalisierung der terminalen Amidgruppe offenkettiger Polyamide via 2-Oxazolin-5-one als ZwischenstufenZum Teil aus der Diplomarbeit von D.O., Universität Zürich 1980.. Vorläufige MitteilungEine vollständige Mitteilung soll in dieser Zeitschrift erscheinen. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 482-487 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Selective Modification of the Terminal Amide Group of Linear Polyamides via 2-Oxazolin-5-ones as IntermediatesTreatment of aqueous or alcoholic solutions of diamides of type 2 with HCl leads to the formation of amide-acids and amide-esters of type 3 (Scheme 1 and Table). It has been shown, that 2-oxazolin-5-ones of type 4 are intermediates of this selective transformation of the disubstituted terminal amide group. The selectivity of the transformation is demonstrated by the reaction sequence shown in Scheme 3. No selectivity has been observed in the acid-catalyzed hydrolysis of triamide 9 with a monosubstituted terminal amide group (Scheme 4). Hydrolysis of the optically active dipeptide derivatives (+)-(L)-13 and (+)-(L)-15 with HBr in nitromethane at 60-80° yields the pure enantiomer (+)-(L)-14 and (+)-(L)-16, respectively (Scheme 5), i.e., no racemization takes place under the reaction conditions.These results show the usefulness of the dimethylamide group as a protecting group for carboxylic acids for example in the peptide synthesis.
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    Dediazoniations of Arenediazonium Ions in Homogeneous Solution. Part XIV. 15N-CIDNP. Investigation of the reactions of diazonium ions in weakly alkaline aqueous solutionsPresented at the 5th IUPAC Conference on Physical Organic Chemistry, Santa Cruz (Cal.), August 1980. For part XIII: see [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 488-503 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 15N-CIDNP. spectra recorded during the reaction of diazonium cations with OH- in weakly alkaline aqueous solutions show that the dediazoniation is at least partially homolytic. The polarizations observed for the diazonium and trans-diazotate ions can be explained by reaction proceeding via a cage involving diazenyl and diazotate radicals using Kaptein's rules and simple intensity considerations.
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    Dediazoniation of Arenediazonium Ions in Homogeneous Solutions. Part XVII. Kinetics and mechanisms of dediazoniation of p-chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions in the presence of oxygenFor part XVI, s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 529-546 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of dediazoniation of p-chlorobenzenediazonium tetrafluoroborate have been studied in buffer solutions in the pH-range 9.0-10.0, ionic strength I = 0.10, at 20.0° in glass and polytetrafluoroethylene vessels. The presence of oxygen (〈5 ppb of O2, 60 to 100 ppb of O2, air, 〉 99% of O2) has a decisive influence on the rate and kinetic order of the dediazoniation. Iodoacetic acid inhibits the reaction, whereas p-chlorophenol has a catalytic effect, and in air and 〉99% of O2 it acts as an autocatalyst. The reaction is subject to general-base catalysis by water, hydroxyl ions, hydrogen carbonate and carbonate ions. The kinetic results are interpreted in conjunction with data concerning the reaction products [2] and a 15N-CIDNP. investigation of a related system [3]. Specific radical chain mechanisms are consistent with the results.
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    Influence of the water content of the solvent on the product distribution in the electrohydrodimerization of 2-cyclohexenonesGraduate-Diploma Thesis (J.P.S.), University of Geneva, 1979.Reported at the 4th EUCHEM Conference on Organic Electrochemistry at Rodez (France), May 1980. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1570-1574 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The product distribution of compounds 2, 3 and 4 formed in the electrohydrodimerization (EHD) of 1 was determined as function of the water content of the solvent (CH3CN). The presence of water favours the formation of the glycols 4 and reduces the relative amounts of 1,6-diketones 2 and hydroxyketones 3, as determined by GC./MS.-analysis.
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    A New, Stereoselective Approach to the [3.3.3]Propellane System: Synthesis of (±)-modhephene. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1575-1578 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The unusual propellane skeleton of the sesquiterpene modhephene (1) has been synthesized starting from cyclopentenone (2). The key step 6 → 7 is an efficient and highly stereoselective intramolecular thermal ene-reaction. Further elaboration of the propellane 7 gave the enone 10 which had been previously converted to (±)-modhephene (1) in three steps.
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    Chemical Selectivities Disguised by Mass Diffusion. VII. A simple model of pH-dependence of product distribution in mixing-disguised azo coupling reactionsPart VI and 7th Communication cf. [1].Results taken from the Ph. D. thesis of H. Belevi [2].. 8th Communication on the selectivity of chemical processesDedicated to the memory of Prof. Norbert Ibl (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1599-1617 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present work a mixing-reaction model is developed to describe the influence of the space- and time-dependent concentration of the leaving group on the pre-equilibria of the reactants and thus on the product distribution of mixing-disguised reactions. The modelling is carried out using a typical example of such reactions, namely azo coupling, where the leaving group is a proton. For this reaction, the existence of characteristic sets of parameters is established, for which the product distribution does not depend on the initial pH-value. These sets of parameters define the isoselectivity points.
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    Total synthesis of racemic ajmalicine and 19-epi-ajmalicineDedicated to Professor George Büchi on the occasion of his 60th birthday (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1663-1671 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: rac.-Ajmalicine (31) and 19-epi-ajmalicine (30) have been synthesized by a convergent route from the preformed D, E-ring moieties 25 and 27 and tryptophyl bromide. Two syntheses of the trans-1-benzoyl-3-vinyl-4-piperidineacetic acid (13), used in the preparation of 25 and 27, are also described.
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    Röntgenstrukturanalysen von Chiralen Ionophoren: NH4NCS-Komplex von 9,9′-Spirobifluoren-22-Krone-5 (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1653-1662 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: X-ray Structure Analyses of Chiral Ionophores: The NH4NCS Complex of 9,9′-Spirobifluorene-22-crown-5In the crystalline NH4NCS complex of 9,9′-spirobifluorene-22-crown-5 (1) the NH4+ ion sits in the centre of the polyether ring, with distances of 2.92-3.15 Å to the five O-atoms and shows at least twofold orientational disorder. In one orientation, three H-atoms point toward O-atoms and the fourth to the N-atom of the anion situated 2.78 Å above the polyether ring. In another, only two H-bonds are formed. The mean planes of the two fluorene parts of the molecule are perpendicular to each other.Crystals of 2,2′-bis (hydroxymethyl)-9,9′-spirobifluorene (2), an intermediate for the synthesis of 1, contain occluded benzene, which cannot be removed under vacuum. X-ray analysis shows that the benzene molecule does not interact with the spirobifluorene in a specific way but merely occupies cages in the crystal packing.
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    Mitteilungen (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1717-1717 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Masthead (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981) 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Mechanisms of Diazo Coupling Reactions. Part XXX. N-Diazo coupling of p-chloroaniline in acetonitrile: Rate-Limiting proton transferPart XXIX, see [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1717-1727 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The N-diazo coupling of p-chloroaniline with p-chlorobenzenediazonium tetrafluoroborate in acetonitrile at 30° shows non-linear base catalysis by water. The results are interpreted in terms of the SE2 mechanism with rate-limiting proton loss at low base concentration; it is postulated, moreover that the reaction proceeds via transition states in which varying degrees of H-bonding from the amine and the intermediate ω-complex to different water species influence the initial step and the base catalysis.
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    Nucleotide. XVXIV. Mitt. s. [1].. Synthese und Eigenschaften von 2′-O-t-Butyldimethylsilyl-5′-O-monomethoxytritylribonucleosid-3′-phosphotriestern, Ausgangssubstanzen für Oligonucleotid-Synthesen (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1704-1716 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nucleotides. XV. Synthesis and Properties of 2′O-t-Butyldimethylsilyl-5′-O-monomethoxytritylribonucleoside-3′-phosphotriesters, Starting Materials for Oligonucleotide SynthesesThe syntheses of two types of fully blocked ribonucleoside 3′-phosphotriesters 6-14 have been achieved in excellent yields from 2′-O-t-butyldimethylsilyl-5′-O-monomethoxytrityl-ribonucleosides 1-5 by phosphorylation with 2-chloro- and 2,5-dichlorophenylphosphorodichloridate respectively and subsequent treatment by cyanoethanol to 6, 8, 10, 12 and 14 and by p-nitrophenylethanol to 7, 9, 11 and 13. These phosphotriesters are valuable starting materials for oligonucleotide syntheses due to the fact that the corresponding phosphotriesters 15-23 with free HO—C(5′) could be obtained by detritylation and the 3′-phosphodiester triethylammonium salts 24-32 by deblocking of the cyanoethyl and the 2,5-dichlorophenyl group respectively. All newly synthesized compounds have been characterized by UV.-and NMR.-spectra as well as C, H, N elementary analyses.
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    Nucleotide. XIVTeil XIII: [1].. Substituierte β-Phenyläthyl-Gruppen. Neue Schutzgruppen für Oligonucleotid-Synthesen nach dem Phosphorsäuretriester-VerfahrenHerrn Prof. Dr. Conrad Hans Eugster in Verbundenheit zum 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1688-1703 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: XIV. Substituted β-Phenyl-ethyl Groups. New Blocking Groups for Oligonucleotide Syntheses by the Phosphotriester ApproachVarious o- and p-substituted β-phenylethanols (2-10) have been synthesized and investigated as blocking groups in the phosphotriester approach. A large number of 5′-O-tritylated thymidine-3′-phosphotriesters (13-36) with two different phosphate protecting groups have been prepared, characterized, and studied according to their chemical stability and usefullness for oligonucleotide syntheses. The combination of a 5′-O-monomethoxytrityl- and a 3′-(2,5-dichlorophenyl, p-nitrophenylethyl)-phosphate function as in 18 turned out to possess optimal properties as a monomeric nucleotide building block due to the fact that these blocking groups can be quantitatively and selectively be removed without harming each other by trifluoroacetic acid in chloroform to 41, by oximate to 42, and by DBU to 43. The base-catalyzed removal of the monosubstituted phenylethyl groups by DBU or DBN respectively as well as the disubstituted phenylethyl groups by triethylamine in aprotic solvents is a β-elimination process leading to phosphodiesters without attack on the P-center.
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    Photochemical free radical formation from aliphatic dicarboxylic acids in solution as studied by electron spin resonance spectroscopyHerrn Professor Conrad Hans Eugster zum 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1739-1751 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various free radicals formed during UV.-irradiation of aliphatic dicarboxylic acids in aqueous and methanolic solution are identified by ESR.-spectroscopy. Their structures point to α-cleavage and photoreduction as the dominant primary photochemical decay processes. The relative contributions of these reactions to the overall photodecomposition depend on solvent and degree of α-alkylation of the acid. Emission ESR.-spectra are found for radicals formed by C, CO-bond cleavage of α-dimethyl substituted acids. The polarization is referred to the triplet mechanism of CIDEP. and indicates this cleavage reaction occurs from a triplet molecular state.
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    Structure and Dynamics of Intramolecular Hydrogen Bonds in Radicals: Substituent, steric and solvent effects (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1910-1929 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The temperature and solvent dependence of the ESR. spectra of a number of semiquinone- and semidione-type radicals have been investigated with the aim of obtaining structural and kinetic information about intramolecular hydrogen bonding. Systematic variation of the chemical structure of the radicals indicates that in many cases formation and/or exchange of intramolecular H-bonds is disturbed or even precluded by steric hindrance or concomitant dynamic processes, such as internal rotation and/or intermolecular proton exchange.
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    Synthesis, Surface Activity and Micelle Formation of Novel Cyanine Dyes (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1943-1948 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis, surface activity and micelle formation of three novel cyanine dyes with amphiphilic character is described. It is illustrated by combined surface tension and absorption measurements that in one case self-assembly is highly cooperative leading to aggregates with unique absorption properties.
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    Structure Elucidation and Synthesis of Flavonol Acylglycosides. III.Part II, see [9].. The synthesis of tiliroside (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1964-1967 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Naturally occurring kaempferol 3-O-β-D-(6″-O-coumaroyl)glucopyranoside (tiliroside) has been synthesized thereby confirming its structure. This is the first acylated flavonoid glycoside to be synthesized.
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    Erratum (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1968-1968 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/hlca.19810640631
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    Über Juliprosin, ein weiteres Alkaloid aus Prosopis julifloraA.DC. 180. Mitteilung über organische Naturstoffe179. Mitt. s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1959-1963 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Juliprosine, a Further Alkaloid Isolated from Prosopis juliflora A.DC.By catalytic hydrogenation of the second base juliprosine (2) isolated from Prosopis juliflora (Leguminosae) the hexahydroderivative 5 was formed. The same product was obtained also by catalytic hydrogenation of juliprosopine (1) of known structure. The absolute configuration of 2 was deduced by comparison of [M]D values of Prosopis alkaloids of known absolute configuration.
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    Laser-Induced Fluorescence and Photoelectron-Photon Coincidence Studies of 3,5-Octadiyne Cation (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1985-1990 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3,5-Octadiyne cation in its lowest excited state has been studied in the gas phase by laser-induced fluorescence and photoelectron-photon coincidence techniques. The excitation spectrum of the Ã2″←2A″ transition has been obtained and yields vibrational frequencies of some of the fundamentals for the excited cationic state. The fluorescence quantum yields and lifetimes at selected energies within the Ã2A″ state have been determined from the coincidence measurements. This provides quantitative data for the discussion of the relaxation behaviour of such an excited open-shell cation.
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    3-Triethylsilyloxypentadienyllithium, a Versatile 1,3-Diene- or Vinyl Ketone-Building Block (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2002-2021 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Deprotonation of the 3-trialkylsilyloxy-1,4-diene 3a and subsequent electrophilic substitution of the non-isolated 3-trialkylsilyoxypentadienyllithium 4 gives the α- and γ-products 8 and/or 6 in good yields. Whereas alkylation of 4 proceeds with variable regioselectivity (Table 1) aldehydes and ketones attack preferentially the γ-position of 4 (Table 2). The desired γ-products 6 may be directly subjected to inter- and intramolecular [4 + 2]-additions as demonstrated by the reactions 5a (≡ 6d) → 7 and 6h → 19 (Schemes 4 and 12). Alternatively, smooth fluoride-promoted silylether-cleavage 6 → 11 (Scheme 8) provides a convenient approach to substituted vinyl ketones such as to the natural products 11f (Table 3). The stereoselective conversion 6k → 23 (Scheme 13) implies an endo-selective intramolecular Diels-Alder addition (26 → 23) and exemplifies the use of 4 as an equivalent of the hypothetical anion IV. Furthermore, some electrophilic substitutions of the hexadienyllithium 15 have been studied (Scheme 10).
    Additional Material: 4 Tab.
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    Visible Light-induced Oxygen Generation and Cyclic Water Cleavage Sensitized by Porphyrins (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1937-1942 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Zinctetramethylpyridylporphyrin (ZnTMPyP4+) in acidic aqueous solution sensitizes efficiently oxygen generation by visible light in the presence of acceptors such as Fe3+ - and Ag+-ions and colloidal RuO2/TiO2 redox catalyst. Hydrogen and oxygen are cogenerated under visible light illumination of ZnTMPyP4+ solutions when a bifunctional catalyst (Pt and RuO2 codeposited onto TiO2) is employed.
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    Etude par des techniques de partition d'énergie des facteurs qui conditionnent l'équilibre conformationnel de propènes disubstitués-1,3 de configuration EEquilibres conformationnels de glucides au niveau de liaisons ω C(sp2), C(sp3), IX; VIII: [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1949-1958 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Effects of the Nature of the C(1) Substituent on the Conformational Equilibrium of (E)-derivatives of 3-Methoxypropene: Determination of the origin of the phenomenon using energy partitioning techniquesIntermolecular interactions taking place in the compounds of the general formula (E)-CH3OCH2CH=CHX were analyzed in terms of one- and two-center interaction energies within the framework of SCF ab initio (STO-3G), Extended Hückel and CNDO methods. The results confirmed the important role of unoccupied orbitals in the stabilization of the different conformers.
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    Mitteilungen (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1969-1970 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/hlca.19810640632
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    Masthead (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981) 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/hlca.19810640701
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    A Study of N-Butyl-(all-trans-retinylidene)amine and Its Protonated Species by 1H- and 13C-NMR. Spectroscopyrunning title: 1H- and 13C-NMR. of visual pigments. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 1969-1984 
    Details
    ISSN: 0018-019X
    Keywords: All-trans-retina ; N-butyl-(all-trans-retinylidene)amine ; 1H-NMR. ; l, 13C-NMR. ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Schiff base of all-trans-retinal was investigated in organic solution by 1H- and 13C-NMR. at high field. Complete assignment of the 1H-NMR. peaks of N-butyl-(all-trans-retinylidene)amine (2) and the N-butyl-(all-trans-retinylidene)-ammonium ion (3) was achieved by INDOR (internuclear double resonance). The vicinal proton coupling constants of the polyene chain show that the π-bond orders remain unchanged in N-butyl-(all-trans-retinylidene)amine relative to all-trans-retinal (1), but change towards larger π-delocalization in the N-butyl-(all-trans-retinylidene)ammonium ion. At --61° only one isomer of N-butyl-(all-trans-retinylidene)ammonium was observed. This was shown to be trans at the imine linkage and independent of the solvent. The trifluoroacetic acid counter-ion can approach the positive charge of the N-atom in the weakly polar solvent dichloromethane but not in the leveling solvent methanol. In dichloromethane the nature of the 1:1 complex is a H-bonded (O-…H-N+) ion-pair whose rate of breaking and forming is rapid at RT. Strong stabilization of the ion-pair resulted from homo-conjugation with a second molecule of trifluoroacetic acid. Excess of acid efficiently diminished the isomerization rate at the C,N-bond.
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    Regioselective Alkylation of the Polyfunctional Nucleophile 1-(Methylthio)-3-triethylsilyloxypentadienyllithium (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2022-2028 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: γ-Selective sulfenylation of the triethysilyloxypentadienyllithium 1 gave the versatile alkylthiodene 4 which on successive deprotonation and alkylation furnished with high regioselectivity the γ-products 6. Fluoride-promoted silylether cleavage 6 → 7 may be followed by intramolecular [4 + 2]-addition 7c → 8 and sulfoxide elimination 8 → 9. The conversions 7b → 12 and 7a → 17 demonstrate the feasibility of 5 to serve as an equivalent of the hypothetical β-deprotonated divinylketone 13 whose two enone units may be unmasked separately.
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    19-O-Acetylchaetoglobosin B and 19-O-Acetylchaetoglobosin D, Two New Metabolites of Chaetomium globosum (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2056-2064 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two new metabolites have been isolated from cultures of Chaetomium globosum. The structures of 19-O-acetylchaetoglobosin B (4) and 19-O-acetylchaetoglobosin D (5) are assigned. The 13C-NMR. spectra of chaetoglobosin A (1), 19-O-acetylchaetoglobosin A (2), chaetoglobosin C (3), 19-O-acetylchaetoglobosin B (4), 19-O-acetylchaetoglobosin D (5) and of cytochalasin G (6), a (3-indolyl)-[11]cytochalasan isolated from Pseudeurotium zonatum, have been interpreted.
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    Die Produkte der Thermolyse von N-(1-Pyridinio)-2-nitroaniliden sind keine Triaziridine, sondern 1, 2-Bis[(2′-nitrophenyl)-azoxyl]-benzole (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2095-2100 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The products of the thermolysis of N-(1-pyridinio)-2-nitroanilides (1) had previously been interpreted as tris (2-nitrophenyl)-triaziridines (3). The present work shows them to be actually 1, 2-bis[(Z)-(2′-nitrophenyl)-ONN-azoxy]benzenes (5). The revised structural assignment is based on the chemical and the spectroscopic (especially 1H-NMR.) properties of 5 and on the results of a X-ray structural analysis.
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    The Electrochemical Measurement of Rate Constants for the Catalyzed Oxidation and Reduction of Water in microheterogeneous systems (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2148-2153 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The appearent first-order rate constants for the oxidation of water by iron tris (bipyridyl) (Fe (bpy)3+3), and reduction of water by methylviologen (MV+) catalyzed by a stabilized RuO2 or Pt-sol, respectively, were measured. Rate constants for water oxidation at pH 7 of 0.4 s-1 and water reduction at pH 4.7 and pH 1 of up to 460 s-1 for different sols were found.
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    Characterization of the Excited State Properties of Some New Photosensitizers of the Ruthenium (Polypyridine) Family (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2175-2182 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The photophysical and electron transfer properties of the lowest excited state of nine ruthenium (polypyridine) complexes have been characterized. The complexes studied are Ru (bpy)3-n (LL)2+n, where n varies from 0 to 3, and LL is 4, 4′-di-t-butyl-2,2′-bipyridine (DTB-bpy), 3, 3′-dimethyl-2, 2′-bipyridine (DM-bpy), or a 2, 2′-diquinolyl derivative (DMCH). The results obtained show that the Ru (bpy)2(DMCH)2+ complex is expected to be a more efficient mediator than Ru (bpy)2+3 in the water-splitting reaction by solar energy.
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    PCILO and CD. Conformational study of sulpiride, a dopamine antagonist (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2183-2188 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational behaviour of sulpiride has been investigated by the quantum mechanical PCILO method and by CD. measurements. The results indicate the predominance of a folded, intramolecularly H-bonded conformer, with extended conformers being only slightly less stable. The pharmacological relevance of these results is briefly discussed.
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    Fragmentation of Homoallylic Alkoxides. Thermolysis of potassium 2-substituted bicyclo [2.2.2]oct-5-en-2-alkoxides (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2193-2202 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermolysis of the potassium 2-substituted bicyclo [2.2.2]oct-5-en-2-alkoxides derived from alcohols 2-17 at 90-120° in hexamethylphosphoric triamide affords unsaturated ketones resulting from allylic bond cleavage. The mechanistic and synthetic aspects of this anionic fragmentation are discussed with reference to the formation of 1-(3′-cyclohexenyl)-2-alkanones 18-28 via initial heterolytic C(1), C(2)-bond cleavage in the substrate alkoxide and regioselective, intramolecular protonation of the resultant transient allylic anion.
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    14-Hydroxytaxodion: Partialsynthese und Reaktionen (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2219-2226 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hitherto unknown diterpenoid 14-hydroxytaxodione (10a) has been prepared by oxidation of 6β-hydroxyroyleanone. Its solutions exhibit a dynamic structural behaviour (UV./VIS/. and NMR.) and lead to an equilibrium mixture of the 11, 14- and the 6, 12-dioxo forms. By methylation and acetylation the 6, 12-dioxo form can be isolated. Chloroform solutions of 14-hydroxytaxodione slowly set up a mixture of coleon V (2a), coleon U (3) and dimeric products (later established as grandidone C, grandidone D and 7-epigrandidone D). Therefore, coleon V (2a) owing to its strong intramolecular H-bond is more stable than 7, 14-dihydroxy-taxodione (2b).
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    14-Hydroxytaxodion als Hauptditerpen in Plectranthus grandidentatus GÜRKE; Isolierung von sieben neuen dimeren Diterpenen aus P. grandidentatus, P. myrianthus BRIQ. und Coleus carnosus HASSK.: Strukturen der Grandidone A, 7-Epi-A, B, 7-Epi-B, C, D und 7-Epi-D (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2227-2250 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Isolation of 14-Hydroxytaxodione from Plectranthus grandidentatus GÜRKE and of Seven New Dimeric Diterpenoids from P. grandidentatus, P. myrianthus and Coleus carnosus Structures of Grandidone A, 7-Epi-A, B, C, D and 7-Epi-DFrom the leaf-glands of the title plant the following abietane diterpenes have been isolated and their structures established by chemical, spectroscopical and X-ray methods: 14-hydroxytaxodione (5, 0,57%), new as a natural product, the already known coleons U (6, 0,17%) and V (7, 0,024%), and furthermore 7 novel dimeric compounds named grandidones (ca. 0,09%), Both grandidone A (1a) and 7-epigrandidone A (1b) as well as grandidone B (2a) and 7-epigrandidone B (2b) are C(7) acetals of 6, 7-Dioxoroyleanone with catecholes such as coleon U (→ 1a, 1b) or coleon V (→ 2a, 2b). Based on the relative configuration at C(7) of 1a which was established by X-ray analysis, the constitutions of 1b, 2a and 2b were assigned by HPLC. - controlled interconversions. The unstable grandidone C (3) is a C(7)-C(7′) linked bis-6-oxoroyleanone with C2-symmetry. Grandidone D (4a) and 7-epigrandidone D (4b) are spiro-dihydrofurans formed from 3 via a hypothetical bis (14-hydroxytaxodione) by intramolecular addition of HO-C(14) or HO-C(14′) to C(7′) to C(7′) or C(7). The relative configuration of 4a was established by X-ray analysis of its diacetate 4c. The absolute configuration of all dimers was established by the partial syntheses from 14-hydroxytaxodion (5) (entirely described in the following communication).
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    Beiträge zur Kenntnis des chromophoren Systems der Corrine: XII [1]. Chemische Eigenschaften des Reaktionsproduktes aus Dicyanocobyrinsäure-heptamethylester mit hypochloriger Säure (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2257-2263 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Contributions to the Knowledge of the Corrin Chromophore: XII [1]. Chemical Behaviour of the Reaction Product of Heptamethyl Dicyano-cobyrinate with Hypochlorous AcidHeptamethyl chloro-cyano-5α, 10, 15-trichloro-6α, 14-dihydroxy-5,6,14,15-tetrahydrocobyrinate (2) in CH3OH/H2SO4 yields with RuO2 under 50 bar hydrogen and at 100° during 2 h a mixture of heptamethyl dicyanocobyrinate (1) with an epimeric ester. Using deuterium instead of hydrogen in this reaction, C(13) comes out as the probable epimerization center.
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    Partialsynthese der Grandidone A, 7-Epi-A, B, 7-Epi-B, C, D und 7-Epi-D aus 14-Hydroxytaxodion (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2251-2256 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Partial Synthesis of Grandidones A, 7-Epi-A, B, 7-Epi-B, C, D and 7-Epi-D, from 14-HydroxytaxodioneOxydative addition of coleon U (6) to 14-hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7-epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7-epigrandidone B (2b) (ca. 3:1). Dimerization of 14-hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7-epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7-epigrandidone D (4b) and interconversions of 4a and 4b were achieved.Oxydative addition of coleon U (6) to 14-hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7-epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7-epigrandidone B (2b) (ca. 3:1). Dimerization of 14-hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7-epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7-epigrandidone D (4b) and interconversions of 4a and 4b were achieved.Oxydative addition of coleon U (6) to 14-hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7-epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7-epigrandidone B (2b) (ca. 3:1). Dimerization of 14-hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7-epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7-epigrandidone D (4b) and interconversions of 4a and 4b were achieved.Oxydative addition of coleon U (6) to 14-hydroxytaxodione (5) in the presence of Fétizon's reagent mainly leads to grandidone A (1a) and 7-epigrandidone A (1b) (ca. 15:1), whereas coleon V (7) and 5 under the same conditions yield grandidone B (2a) and 7-epigrandidone B (2b) (ca. 3:1). Dimerization of 14-hydroxytaxodione (5) gives grandidone C (3; ca. 40%), grandidone D (4a; ca. 50%) and 7-epigrandidone D (4b; ca. 10%). All these compounds obtained by partial synthesis are in every respect identical with the natural products, thus establishing their absolute configurations. The thermal transformation of grandidone C (3) to grandidone D (4a)/7-epigrandidone D (4b) and interconversions of 4a and 4b were achieved.
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    Synthèse de nouveaux types de dérivés C-glycosyliques à partir de sucres acétyléniques ou de leurs équivalents synthétiques partielsDérivés C-glycosyliques XLII; XLI: [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2322-2327 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Novel Types of C-Glycosyl-derivatives from Acetylenic Sugars or Partial Synthetic Equivalents thereofThe concept of synthetic equivalent is not unequivocal and, for example, α-fluoroenamines may behave in some cases as synthetic equivalents of ynamines and, in other situations, quite differently. Some uses of these α-fluoroenamines, ‘partial synthetic equivalents’ of ynamines, for the synthesis of C-glycosyl derivatives of coumarins, chromones, quinolines, quinolones, thietenes and isoxazoles are described.We also report the preparation of a series of mono- and diglycosylthiophenes by reacting HS- with mono- and diglycosylbutadiynes. Acetylenic sugar derivatives have also been used for the synthesis of a diglycosylazaphosphorine and a spirooxolenone.
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    Vorkommen neuer bifunktionellerAls solche wurden in dieser Mitt. Ester bezeichnet, die entweder im Alkohol- oder im Säure-Teil eine weitere (wie eine Alkohol- oder eine Keto-) Funktion aufweisen.. Ester im Römisch-Kamillenöl (Anthemis nobilisL.)Vorgetragen an der 12. Internationalen Arbeitstagung «Vorkommen und Analytik ätherischer Öle», Marburg/Lahn, Juni 1981. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2338-2349 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Occurrence of New Bifunctional Esters In Roman Camomile Oil (Anthemis nobilis L.)Some novel aliphatic esters of the unusual 3-hydroxy-2-methylidenebutyric acid have been found in the commercially available essential oil. Additionally, esters of (Z)-2-methyl-2-butenoic acid of structurally similar diols or other bifunctional alcohols have also been identified. Spectral data as well as a synthetic approach to the new esters of 3-hydroxy-2-methylidenebutyric acid are given.
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    Détermination de la configuration de glycosylaziridines par dichroïsme circulaire. Note de laboratoire (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2350-2355 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: CD.-Based Configurational Assignments of GlycosylaziridinesThe relationship between CD.-curves and the configuration of the trans-2-benzoyl-3-phenylaziridines was known. By studying a series of cis- and trans-2-glycosyl-3-benzoylaziridines we have shown that CD. allows the assignment of the configuration at both asymetric C-atoms. As benzoylaziridines can easily be obtained from cyano- or alkoxycarbonylaziridines without configurational change, the absolute configuration of these last two classes of compounds can also be assessed by this method.
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    Reaktivität und Elektronenstruktur porphinoider Nickelkomplexe14. Mitt. über Synthese und Reaktivität porphinoider Metallkomplexe, 13. Mitt. siehe [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2361-2368 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactivity and Electronic Structure of Porphine-type Nickel ComplexesThe electronic structure of the porphine-type hexaaza[16]annulene-nickel dikation 1′ as well as its mono- and diaddition products 2′ and 3′ (Scheme 2) has been considered by an extended Hückel treatment (SCCC-MO including charge iteration on the central metal atom). Correlations between calculated data and reactivity of the porphinoid compounds 1, 2 and 3 (Scheme 1) are discussed.
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    One-Bond 13C, 13C-Spin Coupling in η4-, η3- and η2-Olefin Transition Metal Complexes13C-NMR. Spectroscopy, Part XXXI; Part XXX: [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2378-2382 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: One-bond 13C, 13C-spin-coupling constants have been measured, with natural isotope abundance, in η4-diene, η3-allyl and η2-ene transition-metal carbonyl complexes. Typical values of 1J(C,C) are given for Fe-, Ru- and Os-complexes with the three types of olefinic ligands. The effects of substituents and the structural significance of the C,C-coupling constants are discussed.
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    Temperature and Concentration Dependent Circular Dichroism of Mono- and Di-cis Isomers of (3S,3′S)-Astaxanthin Diacetate (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2383-2392 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism (CD.) spectra of all-trans-(3S, 3′S) astaxanthin diacetate and its 9-cis, 13-cis, 9,9′-di-cis, 9,13′-di-cis, and 9,13-di-cis isomers conform to the rules previously formulated for optically active carotenoids with a 4-oxo-β-end ring containing an asymmetric C-atom [1]. Thus the CD. bands of the all-trans and the di-cis isomers show the same signs whereas those of the mono-cis isomers have opposite signs. The CD. spectra of all the astaxanthin diacetate isomers invert sign upon cooling to -180°. The CD. spectra of the 9-mono-cis and 9,9′-di-cis isomers and to a lesser extent also those of the 9, 13′-di-cis and 9, 13-di-cis isomers are concentration dependent at -180°, with the longest wavelength band giving at the higher concentration a bisignate CD. curve under the main absorption characteristic of aggregation. This phenomenon has been observed only in isomers with a 9-cis linkage. It is suggested that steric hindrance prevents such aggregation taking place in the other isomers.
    Additional Material: 9 Ill.
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    Iridoid and Aryl Glucosides from Globularia nudicaulis and Globularia nanaPart 5 in the series ‘Glycosides of Globulariaceae’. Part 4: [4]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2401-2404 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The iridoid and aryl glycosidic constituents of Globularia nudicaulis L. and G. nana LAM. are reported. The structure determination of lytanthosalin (10-O-(E)-cinnamoylaucubin), a new acylated iridoid glucoside, isolated from the latter species, is described.
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    Synthese von Astaxanthin aus β-Jonon. I. Erschliessung der enantiomeren C15-Wittigsalze durch chemische und mikrobiologische Racematspaltung von (±)-3-Acetoxy-4-oxo-β-jononHerrn Dr. R. Rüegg zum 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2419-2435 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Astaxanthin from β-Ionone. I. A Route to the Enantiomeric C15-Wittig Salts by Chemical and Microbial Resolution of (±)-3-Acetoxy-4-oxo-β-iononeRacemic 3-acetoxy-4-oxo-β-ionone (10) was synthesized from the industrially accessible intermediate β-ionone (5). Resolution of 10 into its enantiomers was achieved via the corresponding diastereomeric camphanates and by microbial resolution. Site-selective alkylation of racemic and of optically pure 3-acyloxy-4-oxo-β-ionones with vinyl magnesium chloride at -70° furnished the corresponding 3-acyloxy-4-oxo-9-vinyl-β-ionols which could be transformed to the Wittig salts 1, 3 and 4, respectively, following known procedures [1].
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    Technische Verfahren zur Synthese von Carotinoiden und verwandten Verbindungen aus 6-Oxo-isophoron. III. Ein neues Konzept für die Synthese der enantiomeren AstaxanthineTeilweise vorgetragen am 6th International Symposium on Carotenoids 1981, Liverpool, U. K.Teil 2 dieser Reihe s. [1]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2447-2462 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Technical Procedures for the Synthesis of Carotenoids and Related Compounds from 6-Oxo-isophorone. III. A New Concept for the Synthesis of the Enantiomeric AstaxanthinsA new and efficient concept for the total synthesis of (3S, 3'S)- and (3R, 3'R)-astaxanthin (1a and 1c, resp.) in high overall yield and up to 99,2% enantiomeric purity is described. Key intermediates are the (S)- and (R)-acetals 10 and 17, respectively (Scheme 2). These chiral building blocks were synthesized via three different routes: a) functionalization of the enantiomeric 3-hydroxy-6-oxo-isophorons4) 2 and 11, respectively (Scheme 2); b) optical resolution of 3,4-dihydroxy-compound4) 19 (Scheme 3), and c) fermentative reductions of 6-oxo-isophorone derivatives (Schemes 4 and 5). - The absolute configurations of the two intermediates 12 and 13 (Scheme 2) have been confirmed by X-ray analysis. - The final steps leading to the enantiomeric astaxanthins are identical with those described for optically inactive astaxanthin [1].
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    Synthese von optisch aktiven, natürlichen Carotinoiden und strukturell verwandten Naturprodukten. IX. Synthese von (3R)-Hydroxyechinenon, (3R, 3′R)- und (3R, 3′S)-Adonixanthin, (3R)-Adonirubin, deren optischen Antipoden und verwandten VerbindungenHerrn Dr. R. Rüegg zum 60. Geburtstag gewidmet (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2469-2484 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Optically Active Natural Carotenoids and Structurally Related Compounds. IX. Synthesis of (3R)-Hydroxyechinenone, (3R, 3′R)- and (3R, 3′S)-Adonixanthin, (3R)-Adonirubin, Their Optical Antipodes and Related CompoundsThe synthesis of racemic and optically active hydroxyechinenone (12-14), adonixanthin (16-19), adonirubin (22-24), meso-astaxanthin (26) and their corresponding diosphenols 15, 20, 21, 25, 27, 28, and 29) by Wittig reaction is reported, starting from suitable C15-phosphonium salts and C10-aldehydes.
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    Errata (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2495-2496 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/hlca.19810640758
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    Masthead (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981) 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Enamines. II. A theoretical and photoelectron spectroscopic study of the molecular and electronic structures of aliphatic enamines (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2497-2507 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Comparison of PE. spectroscopic data for four series of enamines (including azetidine and some aziridine derivatives) for studying the influence of amine-ring size on electronic structure show the pyrrolidino group to exhibit the strongest amine/double bond coupling in sterically unconstrained enamines. However, the azetidino group accommodates best steric congestion due to dialkyl substitution at the β-position of the enamine unit. Quantum-chemical calculations of equilibrium structures and energy profiles for amine rotations in model enamines by the PRDDO SCF method agree satisfactorily with experimental results. Notable exceptions are pyrrolidine derivatives for which PRDDO overestimates the amount of N-pyramidality.
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    Activated C,H-Acids: N-Alkyl-9-fluorenimines. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2524-2527 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Substituted 9-fluorenimines 1 are easily prepared from primary amines or aminoesters and 9-fluorenimine: their conjugate carbanions 2 are formed by the action of alkoxides and are reprotonated to 1 or to the tautomeric 9-alkylidenamino-fluorenes 3 depending upon substituents.
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    Synthetic Methods and Reactions. Part 106. Suppression of anchimerically assisted rearrangement products in the synthesis of α-fluorocarboxylic acids from α-amino acids with 48:52 (w/w) hydrogen fluoride/pyridine [1] (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2528-2530 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Anchimerically assisted rearrangement, observed in the fluorination of some α-amino acids with 70 : 30 (w/w) hydrogen fluoride/pyridine (by weight) in the presence of NaNO2, is substantially or fully suppressed by using the less acidic reagent 48 : 52 (w/w) hydrogen fluoride/pyridine.
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    Structure-Activity Relationship of Oxygenated Morphinans. V. Narcotic agonist and antagonist activity in the 14-hydroxymorphinan series. Preliminary communication (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2540-2543 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of several 14-hydroxymorphinans, using oxymorphone (= 3, 14-dihydroxy-4,5-epoxy-N-methylmorphinan-6-one, 1) as starting material, is described. The antinociceptive potency of the N-methyl substituted 14-hydroxy-morphinans was determined. Thus, in order of antinociceptive potency, 14-hydroxy-4-methoxy-N-methylmorphinan-6-one (5) 〉4,5-epoxy-14-hydroxy-N-methyl-morphinan-6-one (3)〉4, 14-dihydroxy-N-methylmorphinan-6-one (4)〉14-hydroxy-4-methoxy-N-methylmorphinan (11) ≈4, 14-dihydroxy-N-methylmorphinan (12). The most potent compound in this series, 14-hydroxy-4-methoxy-N-methyl-morphinan-6-one (5), was found to have about six times the potency of morphine; it was equipotent with levorphanol.
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    Tasmanin, ein neues Indolalkaloid aus Aristotelia peduncularis (LABILL.) HOOK. F. 181. Mitteilung über organische Naturstoffe180. Mitt. s. [1].Teil der geplanten Dissertation von R.K., Universität Zürich. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2555-2562 
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    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Tasmanine, a New Indole Alkaloid from Aristotelia peduncularis (LABILL.) HOOK. F.The new indole alkaloid tasmanine (3) was isolated from Aristotelia peduncularis. Its relative configuration was elucidated on the basis of spectroscopic data (mainly NMR. spectra). It is closely related to the other known alkaloids from Aristotelia with double substitution at the indole nucleus. A biosynthetic pathway to these related natural compounds is proposed; also a biogenetic numbering system is suggested.
    Notes: No Abstract.Another representative of this group of alkaloids, aristoteline (2), was also isolated from A. peduncularis. This natural compound has previously been isolated from A. serrata and A. chilensis.
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    A Convergent Synthesis of (±)-α- and β-HimachalenesPresented by one of us (W.O.) at the 6th International Symposium on Synthesis in Organic Chemistry, Cambridge (England), July 1979. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2592-2597 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (±)-α and β-Himachalene, 5 and 6, have been synthesized in a convergent manner from 3,3-dimethylacrolein (9), the ester enolate 10 and the silyloxypentadienyllithium 7. The key steps are the regioselective γ-addition of the dienal 13 to 7 and the intramolecular Diels-Alder addition 15 → 16. Hydrogenolysis of the diethylphosphate group and functionalization at C (5) completed the synthesis of 5 and 6.
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    Photochemical Reactions. 125th communication [1]. Photochemistry of homoconjugated cyclobutanones. I. Synthesis and photolysis of a Spiro [3.6]deca-5, 7-dien-1-one (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2598-2605 
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    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound 4 was prepared in 54% overall yield from eucarvone (5). On triplet sensitization 4 gives two products resulting from a 1,2-acyl shift (8 and 9), whereas singlet excitation of 4 causes decarbonylation and ketene elimination (4 → 10 and 11).
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    Umlagerung von α-Halogen- in α′-Halogen-cyclobutanone, Schlüsselstufe einer variationsreichen Synthese von Pyrethroiden16. Mitt. über Synthese und Reaktivität von Vierringverbindungen. 15. Mitt.: [1].Auszugsweise vorgetragen am International Symposium on Chemistry of the Pyrethroids vom 16. bis 19. Juli 1979 in Oxford, am 1st European Symposium on Organic Chemistry vom 20. bis 23. August 1979 in Köln, am 178th ACS Meeting vom 9. bis 14. September 1979 in Washington, D.C. (Abstract ORGN-010) sowie an der Herbstversammlung der Schweizerischen Chemischen Gesellschaft am 19. und 20. Oktober 1979 in Bern. Vorläufige Mitt.: [2]. (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2571-2586 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Rearrangement of α-Halogen- to α′-Halogen-cyclobutanones, Key Step of a Highly Versatile Synthesis of Pyrethroidsα-Halogenocyclobutanones, which are readily available by [2 + 2]-cycloaddition of haloketenes to terminal olefins (e. g. 5 → 6), undergo an efficient and stereoselective cine-rearrangement to α′-halogenocyclobutanones in the presence of catalysts such as tertiary amines, HX acids or quaternary ammonium salts (e. g. 6 → 7, Table 1). Preparative as well as mechanistic aspects of the cine-rearrangement are discussed. The 2,4-cis-disubstituted cyclobutanones 7-32 thus formed represent valuable intermediates in a new synthesis of pyrethroids 1.The X-ray structure of 2-chloro-4-(2,2,2-trichloroethyl)-3,3-dimethylcyclobutanone (7), the most important precursor of cis-3 (X = Cl) shows the following features: a puckered cyclobutanone ring (dihedral angle 31°), 2,4-cis-di-pseudoequatorial arrangement of the chloro and trichloroethyl substituents, and an endo-deviation (0.225 Å; 11°) of the carbonyl O-atom from the plane formed by C(1), C(2) and C(4) (Fig. 2).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640813
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    Electronic Resource
    Tetrameric Cubic Structures of Two Solvated Lithium Enolates (1981)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2617-2621 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of the crystalline lithium enolates derived from 3, 3-dimethyl-2-butanone and from cyclopentanone have been determined by X-ray analysis. Both structures are tetrameric aggregates based on a Li4O4-cube, each Li+-ion being additionally bonded to the O-atom of a tetrahydrofuran solvent molecule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19810640819
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