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  • 1
    Electronic Resource
    Electronic Resource
    Silylene Reactions with Buta-1,3-diynes: Cycloadditions, Insertions, and Rearrangements (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2301-2307 
    Details
    ISSN: 1434-1948
    Keywords: Multiple bonds ; Silicon ; Silylene ; Cycloadditions ; Insertions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Di-tert-butylsilylene, generated by photolysis of hexa-tert-butylcyclotrisilane 1 or 1,1-di-tert-butyl-trans-2,3-dimethyl-silirane (2), reacts with the 1,3-diyne (tBu-C≡C-)29 to furnish the dialkynylsilane 11 via the isolable alkynylsilirene 10. Photolysis of excess 1 in the presence of 9 furnishes the C-C linked 2,2′-disilirene 12 which, upon prolonged irradiation, rearranges to the 2,5-disilabicyclo[2.2.0]hexa-1(6),3-diene (13). Treatment of 9 with diarylsilylenes, formed by irradiation of hexamethyl-2,2-dimesityltrisilane (3) or hexamethyl-2,2-bis(2,4,6-triisopropylphenyl)trisilane (4), gives the corresponding alkynylsilirenes 14 and 15, respectively. Photolysis of 1 or 2 in the presence of (Me3Si-C≡C-)216 yields the dialkynylsilane 17 which, on further reaction with 2, yields the 2,5-disilabicyclo[2.2.0]hexa-1(6),3-diene (18). Irradiation of 3 in the presence of 16 affords the cis- and trans-isomeric 1,3-dimethylene-2,4-disila-cyclobutane derivatives cis-21 and trans-21, presumably via a 1-silaallene intermediate. The structures of 12, 15, 18, cis-21, and trans-21 have been determined by X-ray crystallography.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Silylene Reactions with Nitrogen Multiple Bonds: Additions and Rearrangements (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1755-1758 
    Details
    ISSN: 1434-1948
    Keywords: Silicon ; Silylene ; Azobenzene ; 1-Adamantyl azide ; Addition reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactions of the sterically encumbered silylenes R2Si: (R = 2,4,6-Me3C6H2, 2,4,6-iPr3C6H2) with azobenzene are thought to proceed via the [2+1] cycloaddition products, followed by insertion of the N-N single bond into the ortho-C-H bond of one of the phenyl rings or into the C-HMe2 bond of one of the ortho-isopropyl groups to furnish the 1,3-diaza-2-silaindan (4) or 1-aza-2-silaindan (5) derivatives, respectively. The reactions of these silylenes with 1-adamantyl azide seem to proceed through the silanimines and 4-azahomoadamantene intermediates which, by [2+2] cycloadditions, afford the 1,3-diaza-2-silacyclobutane derivatives 11 and 12. The structures of 4, 5, 11, and 12 were determined by X-ray crystallography.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Utilization of Industrial Waste Materials, 10Part 9, 8: Ref.[1]. - Part 7: Ref.[8].. - Synthesis of New Chiral Bicyclic 3-hydroxypiperidines - Highly Diastereoselective Ring Expansion of the Azabicyclo[3.3.0]octane System to Chiral Piperidine Derivatives (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 573-579 
    Details
    ISSN: 0947-3440
    Keywords: Amino alcohols ; Bicyclic pyrrolidine and piperidine derivatives ; Diastereoselective ring expansion ; Chiral auxiliaries ; Waste prevention ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New, chiral bicyclic 3-hydroxypiperidines (4S)-2a-e are synthesized from the β-amino alcohols (3R)-1a-e. In an one-step reaction (4S)-2a-e are obtained by a high diastereoselective ring expansion (dr ≥ 95:5). As well, the amino alcohol (3S)-1a leads to the corresponding rearranged epimer bicyclic piperidine derivative (4R)-2a (dr ≥ 95:5). Thus, it is possible to clarify the influence of the three stereogenic centers of the parent compound regarding the diastereoselectivity of the ring expansion. After oxidation of the tert-amino sec-alcohol (4S)-2a to the corresponding α-amino ketone 4, new 3-hydroxypiperidines (4Ξ)-5a, b12 and (4RS)-6 are obtained by a diastereoselective Grignard addition. Furthermore, the achiral and the chiral reduction of 4 to the β-amino alcohols (4S)-2a and (4R)-2a is described. These are further examples of the utilization of industrial waste material (all-R)-2-azabicyclo[3.3.0]octane-3-carboxylic acid (all-R)-3.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970319
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  • 4
    Electronic Resource
    Electronic Resource
    Utilization of Industrial Waste Materials, 11.Part 10: Ref. Synthesis of New, Chiral β-sec-Amino Alcohols - Diastereodivergent Addition of Grignard Reagents to α-Amino Aldehydes Based on the (all-R)-2-Azabicyclo[3.3.0]octane SystemDedicated to Professor Dieter Seebach on the occasion of his 60th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2133-2146 
    Details
    ISSN: 0947-3440
    Keywords: Amino alcohols ; Chiral auxiliaries ; Diastereoselective Grignard reactions ; Proline analogues ; Homogenous catalysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New, chiral β-sec-amino alcohols (αR,βR)-11a-13a, (αS,βR)-11b-17b, (αS,βS)-11c, 12c, 15c, 17c and (αR,βS)-11d, 12d, 15d, 17d have been synthesized from the enantiomerically pure amine (all-R)-1a via diastereomeric, N-tert-butoxycarbonyl-protected aldehydes 3. Grignard additions proceed in fair yields with a high degree of diastereofacial stereoselection (diastereomeric ratios dr up to ≥ 95:5) with non-chelation control, generally in favor of the anti-(erythro) structures. A mechanistic interpretation of the stereochemical course of this reaction is presented. The stereodifferentiating ability of selected stereoisomeric (erythro)- and (threo)-amino alcohol structures were tested in homogeneous catalysis, e.g. in two model reactions (optical purities up to 95%).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971016
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