Stereoisomers of 1,3,5,7-Tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane: Synthesis and Structures in the Crystal
作者:Masafumi Unno、Yasuaki Kawaguchi、Yukiko Kishimoto、Hideyuki Matsumoto
DOI:10.1021/ja043894m
日期:2005.2.1
formation of cis-trans-cis-1 in 92% yield. The structures of cis-cis-trans-1, cis-trans-cis-1, and all-cis-1 were determined by X-ray crystallography. All isomers were found to construct unique packing structures by intermolecular hydrogen bonding; cis-trans-cis-1 composed an infinite antiladder structure, and cis-cis-trans-1 formed a sheetlike structure.
1,3,5,7-四羟基-1,3,5,7-四异丙基环四硅氧烷的所有四种立体异构体的首次合成,[i-PrSiO(OH)]4 (all-trans-, cis-cis-trans-, cis-trans-cis- 和 all-cis-1),呈现。制备起始化合物全反、顺-顺-反-、顺-反-顺-和全-顺-1,3,5,7-四芳基-1,3,5,7-四异丙基环四硅氧烷通过相应的芳基异丙基二氯硅烷 i-PrArSiCl2 (Ar = Ph, p-tolyl) 水解,然后分离异构体。四芳基环四硅氧烷的脱苯基氯化和随后的水解相结合被证明是将芳基取代的环四硅氧烷立体定向转化为 (i-PrSiO(OH))4 的有效方法。例如,用HCl和AlCl3处理顺-反-顺-1,3,5,7-四苯基-1,3,5,7-四异丙基环四硅烷,然后在吡啶存在下水解,以 92% 的产率独家形成顺式-反式-顺式-1。cis-cis-trans-1、cis-trans-cis-1