Asymmetric γ-Deprotonation and Substitution Reactions of (Z)-1,3-Diphenyl-1-propenylN,N-Diisopropylcarbamate
作者:Jenny Reuber、Roland Fröhlich、Dieter Hoppe
DOI:10.1002/ejoc.200500145
日期:2005.7
(Z)-1,3-Diphenyl-1-propenyl N,N-diisopropylcarbamate (6d) is deprotonated by n-butyllithium/(–)-sparteine (5) with a high degree of enantiotopic differentiation in the γ-position to form the enantiomerically enriched allyllithium derivative 7d. Despite of its high mesomeric stabilization it shows a high degree of configurational stability. Trapping with carbonyl electrophiles proceeds exclusively in
(Z)-1,3-二苯基-1-丙烯基 N,N-二异丙基氨基甲酸酯 (6d) 被正丁基锂/(–)-sparteine (5) 去质子化,在 γ 位具有高度的对映体分化,形成富含对映异构体的烯丙基锂衍生物 7d。尽管具有高度的介孔稳定性,但它显示出高度的构型稳定性。如直接分配和立体化学相关所示,用羰基亲电试剂捕获仅在 syn-SE' 取代中进行。因此,建议涉及 η3 复合物。在转移到类似的钛酸烯丙酯16之后,提供对映异构和非对映异构纯的高羟醛产物17。有证据表明存在竞争性复古高羟醛反应。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)