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Diastereoselective Construction of Contiguous Chilal Centers by the Aldol Reaction of Acylsilane Silyl Enol Ethers.

通过酰基硅烷甲硅烷基烯醇醚的羟醛反应非对映选择性构建连续手性中心。

基本信息

批准号：
03650694
负责人：
NAKAJIMA Tadashi
金额：
$ 1.22万
依托单位：
KANAZAWA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

There has been considerable interest in recent years in the stereoselective formation of multiple chiral centers using aldol reaction between prochiral enolates and aldehydes. We disclosed here an convenient method of diastereoselective construction of the three or four contiguous chiral centers using the Lewis acid mediated reaction of acylsilane silyl enol ethers (I) with acetals and the subsequent nucleophilic addition to the carbonyl group of the resulting acylsilanes (II).Treatment of E-or Z-acylsilane silyl enol ethers (I) derived from acylsilanes having enolizable methylene proton with a mixture of aldehyde dimethylacetals and TiCl_4 in dichloromethane gave the corresponding 2,3-anti-3-methoxy-1-silyl-1-alkanones (II) in high diastereo excess,independent of the double bond stereochemistry of I used. The similar reaction of E-I with d,1-phenylpropionealdehyde afforded 2,3-syn-3,4-syn-3-methoxy-1-silyl-1-butanal (V) in high stereoselectivity.The resulting acylsilane 2,3-anti-II and 2,3-syn-3,4-syn-V were subjected to the nucleophilic reaction with alkyl or phenyllithium to yield the corresponding 3-methoxy-1-silyl-1-alkanols with three and four contiguous asymmetric centers (III and VI, respectively) stereoselectively. The protiodesilylation of III and VI with F^- reagent to afford the corresponding 1,2-anti-al- kanols with three and four contiguous asymmetric centers, IV and VII in 95-99% diastereo excess.

近年来，利用前手性烯醇和醛之间的醛醇反应立体选择性形成多个手性中心的研究引起了人们的极大兴趣。我们在这里公开了一种方便的非对映选择性构建三个或四个连续手性中心的方法，使用刘易斯酸介导的酰基硅烷硅烯醇醚(I)与缩醛的反应，以及随后在生成的酰基硅烷（II）的羰基上亲核加成。由具有可烯化亚甲基质子的酰基硅烷衍生的e -或z -酰基硅烷硅烯醇醚(I)与乙醛二甲基缩醛和TiCl_4的混合物在二氯甲烷中处理，得到相应的2,3-反-3-甲氧基-1-硅基-1-烷酮（II），具有高度的非立体过量，与I所使用的双键立体化学无关。E-I与d，1-苯丙烯醛的类似反应产生2,3- syn3,4 - syn3 -甲氧基-1-硅基-1-丁醛(V)具有高立体选择性。得到的2,3-抗- ii和2,3-syn-3,4-syn- v型酰基硅烷与烷基或苯基锂发生亲核反应，立体选择性地生成具有3个和4个连续不对称中心（分别为III和VI）的3-甲氧基-1-硅基-1-烷醇。用F^-试剂对III和VI进行原硅酰化反应，得到相应的具有3个和4个连续不对称中心的1,2-抗al- kanols， IV和VII在95-99%的非映体过量。