1,2-Silyl-Migrative Cyclization of Vinylsilanes Bearing a Hydroxy Group: Stereoselective Synthesis of Multisubstituted Tetrahydropyrans and Tetrahydrofurans<sup>1</sup>
作者:Katsukiyo Miura、Takeshi Hondo、Shigeo Okajima、Takahiro Nakagawa、Tatsuyuki Takahashi、Akira Hosomi
DOI:10.1021/jo026006j
日期:2002.8.1
trans-2-alkyl-3-silyltetrahydropyrans 2 exclusively (trans/cis = >99/1 to 97/3). The cyclization efficiency and rate strongly depended on the geometry of the C-C double bond and the silyl group. The use of (E)-vinylsilanes resulted in lower yields with poor cis-selectivity. In the cyclization of (Z)-1 (R = Bu), the silyl group used, the reaction time, and the yield of 2 were as follows: SiMe(2)Ph, 9.5 h, 75%;
已经研究了酸催化的羟基向α-烷基化的乙烯基硅烷的分子内加成。用5 mol%的TiCl(4)在CHCl(3)中处理(Z)-5-烷基-5-甲硅烷基-4-戊烯-1-醇1(R =烷基)得到反式-2-烷基-3-甲硅烷基四氢吡喃仅2个(trans / cis => 99/1至97/3)。环化效率和速率很大程度上取决于CC双键和甲硅烷基的几何形状。(E)-乙烯基硅烷的使用导致较低的收率和较差的顺式选择性。在(Z)-1(R = Bu)的环化中,所用的甲硅烷基基团,反应时间和2的产率如下:SiMe(2)Ph,9.5h,75%; m / z。SiMe(3),7.5小时,66%;SiMePh(2),24小时,58%;SiMe(2)-t-Bu,0.75小时,85%; SiMe(2)Bn,1.5 h,78%。该1,2-甲硅烷基迁移环化可用于三取代四氢吡喃的立体选择性合成。1-,2-或3-取代的(Z)-5-甲硅烷基-