Stereospecificity in the Lewis acid promoted allylation reaction of 3,3-disubstituted allyltins toward aldehydes
作者:Yutaka Nishigaichi、Akio Takuwa
DOI:10.1016/s0040-4039(98)80032-4
日期:1999.1
The Lewisacid-promotedreaction of 3,3-disubstituted allyltins towardaldehydes was found to be stereospecific; the (E)-reagent gave syn-products and the (Z)-one gave anti-products. This is in contrast to that of 3-mono-substituted congeners which are known to react syn-stereoselectively regardless of their double bond geometry. The reaction was assumed to proceed via an acyclic syn-synclinal transition
Chromium(II)-Mediated Stereodivergent Additions of Allylic Phosphates and Halides to Aldehydes
作者:Stefan Nowotny、Charles E. Tucker、Carole Jubert、Paul Knochel
DOI:10.1021/jo00114a026
日期:1995.5
The addition of gamma-disubstituted allylchromium(III) reagents to aldehydes proceeds in a stereodivergent manner, in contrast to the case of gamma-monosubstituted allylchromium(III) species. The method allows the preparation of a variety of homoallylic alcohols bearing a quaternary center of defined relative configuration in the alpha-position. The preparation of both stereomeric homoallylic alcohols 13 is possible by using either of the two (E)- or (Z)-allylic precursors. The reaction has been extended to a gamma-monosubstituted beta-(trimethylsilyl)allylic system. The intermediate allylic chromium(III) reagents can be conveniently prepared from the corresponding phosphates (or chlorides) in DMPU or THF in the presence of catalytic amounts of LiI.
STEREOSELECTIVE ACYCLIC SYNTHESIS VIA ALLYLMETALS: STRUCTURAL DEPENDENCE IN A LEWIS-ACID CATALYZED ADDITION OF ALLYLTINS TO ALDEHYDES
作者:Masato Koreeda、Yoshio Tanaka
DOI:10.1246/cl.1982.1299
日期:1982.8.5
Lewis-acid catalyzed reaction of allyltins with aldehydes at −78 °C provide homoallyl alcohols with high stereoselectivity; 2-alkenyltins in general provide erythro adducts preferentially with an erythro/threo ratio greater than 12/1, whereas only threo adducts can be obtained from E-cinnamyltins.
路易斯酸催化烯丙基锡与醛在 -78 °C 下的反应提供具有高立体选择性的高烯丙醇;2-烯基锡通常优先提供赤/苏比大于12/1的赤加合物,而从E-肉桂锡只能获得苏加加合物。