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Stereoselective Synthesis Using iVee-Membered Carbon Ring and Silyl Groups

使用 iVee 碳环和甲硅烷基进行立体选择性合成

基本信息

批准号：
12650850
负责人：
SEGI Masahito
金额：
$ 2.3万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Reactions of acylsilanes with sulfur methylides proceed with cationotropy or anionotropy of silicon in the betaine intermediate to give the corresponding enolsilanes or β-ketosilanes. The product's ratio can be controlled by manipulating the reaction conditions. The reaction with sulfur ethylides and that with sulfur cyclopropylide result in the preferential formation of the corresponding α,β-epoxysilanes and cyclopropylidene(siloxy)methane derivatives, respectively. In contrast, various acylsilanes react with α-sulfinyl carbanions such as α-lithioalkyl phenyl sulfoxide to give the regiochemically pure enolsilanes produced by cationotropy of silicon to β-oxygen in the α-silyl-β-oxysulfoxide intermediate. The product's selectivity in these reactions depends on the leaving ability of sulfur compounds from the intermediate. In the reaction using sulfur ylides the elimination of neutral sulfur compound from the betaine intermediate occurs prior to the silicon migration, whereas in the reaction with α-sulfinyl carbanions the cationotropy of silicon assists the elimination of sulfenate ion from the β-oxysulfoxide intermediate.On the other hand, rearrangement of cyclopropylsilylcarbinols derived from cyclopropylacylsilanes with TsOH in methanol proceeds stereoselectively to give 4-silylhomoallyl methyl ether. The cyclopropylsilylcarbinols bearing n- or s-alkyl group on the carbinyl carbon produce E-4-silylhomoallyl methyl ethers, and those bearing f-butyl group afford Z-4-silylhomoallyl methyl ethers. E- and Z-4-silylhomoallyl methyl ethers are protiodesilylated with TBAF to yield the corresponding Z- and E-olefins, respectively.The asymmetric reduction of acylsilanes, in the presence of catalytic amounts of borane-(-)- diphenylhydroxymethyl pyrrolidine complex, with borane leads to the corresponding optically active silylcarbinols in quantitative chemical yield and in high enantiomeric excess.

酰基硅烷与硫亚甲基的反应在甜菜碱中间体中的硅的阳离子或阴离子的作用下进行，得到相应的烯醇硅烷或β-酮基硅烷。产物的比例可以通过控制反应条件来控制。与硫代乙叉和硫代环丙叉反应，分别优先生成相应的α，β-环氧硅烷和环丙叉（甲硅烷氧基）甲烷衍生物。相反，各种酰基硅烷与α-亚磺酰基碳负离子如α-锂烷基苯基亚砜反应，通过α-甲硅烷基-β-氧亚砜中间体中的硅向β-氧的阳离子转移产生区域化学纯的烯醇硅烷。在这些反应中，产物的选择性取决于硫化合物从中间体离开的能力。在使用硫叶立德的反应中，中性硫化合物从甜菜碱中间体中的消除发生在硅迁移之前，而在与α-亚磺酰基碳负离子的反应中，硅的阳离子向性有助于从β-氧亚砜中间体中消除亚磺酸根离子。用TsOH在甲醇中对衍生自环丙基酰基硅烷的环丙基甲硅烷基甲醇进行立体选择性重排，得到4-甲硅烷基高烯丙基甲基醚。环丙基甲硅烷基甲醇的碳上带有正烷基或仲烷基，生成E-4-甲硅烷基高烯丙基甲基醚，而带有叔丁基的环丙基甲硅烷基甲醇生成Z-4-甲硅烷基高烯丙基甲基醚。E-和Z-4-甲硅烷基高烯丙基甲基醚分别用TBAF进行质子脱甲硅烷基化，得到相应的Z-和E-烯烃，在催化量的硼烷-（-）-二苯基羟甲基吡咯烷络合物存在下，用硼烷不对称还原酰基硅烷，得到相应的光学活性甲硅烷基甲醇，化学产率定量，对映体过量。