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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，利用前手性烯醇化物与醛的羟醛缩合反应立体选择性地形成多个手性中心的研究引起了人们极大的兴趣。我们在此公开了一种使用刘易斯酸介导的酰基硅烷甲硅烷基烯醇醚（I）与缩醛的反应和随后亲核加成到所得酰基硅烷（II）的羰基上的非对映选择性构建三个或四个相邻手性中心的方便方法。由具有可烯醇化的亚甲基质子的酰基硅烷与醛二甲基缩醛和TiCl_4的混合物在二氯甲烷中衍生得到高度非对映过量的相应的2，3-反式-3-甲氧基-1-甲硅烷基-1-烷酮（II），独立于所使用的I的双键立体化学。E-I与d，1-苯基丙醛类似反应，高立体选择性地得到2，3-顺-3，4-顺-3-甲氧基-1-甲硅烷基-1-丁醛（V）。4-syn-V分别与烷基锂或苯基锂发生亲核反应，得到相应的3-甲氧基-1-硅基-1-烷醇（分别为III和VI）立体选择性。III和VI用F^-试剂进行质子脱甲硅烷基化，得到相应的具有三个和四个连续不对称中心的1，2-反烷醇，IV和VII的非对映体过量为95-99%。