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  • Chemoselectivity  (2)
  • Brachyteles arachnoides  (1)
  • 1995-1999  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Behavioral Correlates of Dispersal in Female Muriquis (Brachyteles arachnoides) (1999)
    Springer
    International journal of primatology 20 (1999), S. 941-960 
    Details
    ISSN: 1573-8604
    Keywords: muriqui ; Brachyteles arachnoides ; female transfer ; social dispersal ; intergroup ; nearest neighbors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We documented four adolescent female transfers—two emigrations, two immigrations—during a 12-month study from August 1994 to July 1995 on one group of muriquis (Brachyteles arachnoides) at Estação Biológica de Caratinga in Minas Gerais, Brazil. Intergroup transfers occurred throughout the year independent of season. A total of 613 focal samples of 10-min duration conducted on six adolescent females (5–9 years of age) revealed significant differences in the behavior of migrant versus natal resident females. During the seasons encompassing their respective group transfers, both emigrants and immigrants devoted more of their time to resting than resident females belonging to the same age cohorts did. Time spent feeding on mature fruit was higher for one emigrant and lower for both immigrants compared to the two resident females. Emigrant females had fewer neighbors within a 1-m radius than resident females did, whereas immigrant females were within a 1-m radius of adult females and within a 5-m radius of adult males more often than resident adolescent females were. Adolescent females were displaced on 26 occasions. Displacements occurred mainly during the dry seasons (n = 21) and mainly at food sources (n = 21). Using the number of focal samples conducted on each female as an estimate of observation time, immigrant females were displaced at twice the rate of residents. However, like other behavioral differences detected between resident and migrant adolescent females, differences in individual displacement rates were evident only during the season in which each of the immigrants joined the group. Collectively, our findings imply that female intergroup transfer in this population involves relatively mild, short-term costs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020882719850
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  • 2
    Electronic Resource
    Electronic Resource
    1-Methylgeraniol as Novel Regio- and Diastereoselective Probe for Hydrogen Bonding in Hydroxy-Assisted Oxygen-Transfer Reactions (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 1365-1369 
    Details
    ISSN: 0947-3440
    Keywords: Epoxidations ; Diastereoselectivity ; Hydrogen bonding ; 1-Methylgeraniol ; Chemoselectivity ; Peroxides ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chiral 1-methylgeraniol has been designed and applied for epoxidation reactions as a mechanistic probe, which allows to assess simultaneously in one and the same molecule regio- and stereochemical information. Of the two trisubstituted double bonds, the terminal 7,8 one reflects kinetic preferences on account of its greater π nucleophilicity, the 3,4 one with the chiral allylic hydroxy functionality expresses diastereoselective directivity through hydrogen bonding. The combination of regio- and stereoselectivity provides a novel and powerful mechanistic tool to differentiate electronic and steric effects of oxidants. Thus, various epoxidizing agents have been employed and the mechanistic implications derived from the product ratios are well in line with those reported, which exemplifies the validity of the probe.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970713
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  • 3
    Electronic Resource
    Electronic Resource
    Regio-, Diastereo-, and Chemoselectivities in the Dioxirane Oxidation of Acyclic and Cyclic Allylic Alcohols by Methyl(trifluoromethyl)dioxirane (TFD): A Comparison with Dimethyldioxirane (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 349-354 
    Details
    ISSN: 1434-193X
    Keywords: Dioxirane ; Oxidation ; Allylic alcohols ; Regioselectivity ; Diastereoselectivity ; Chemoselectivity ; Epoxides ; Enones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solvent-dependent shift in the regioselectivity of the geraniol epoxidation by methyl(trifluoromethyl)dioxirane (TFD) reveals that as for the less reactive dimethyldioxirane (DMD), hydrogen bonding stabilizes the transition state of the epoxidation. In protic media, the hydrogen bonding is exerted intermolecularly by the solvent, whereas in unpolar, non-hydrogen-bonding solvents intramolecular assistance through the adjacent hydroxy functionality comes into the play and the attack on the allylic alcohol moiety is favored. For chiral allylic alcohols, additional steric interactions control the π-facial selectivity in the conformationally fixed transition state. Analogous to DMD, the preferred dihedral angle in the hydrogen-bonded transition state of the TFD epoxidation constitutes approximately 130°, but contrary to DMD and for synthetic purposes important, the allylic alcohols and derivatives 1 and 3-5 investigated here are chemoselectively epoxidized by TFD without formation of the corresponding enones.
    Type of Medium: Electronic Resource
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