Ring-opening reactions of cyclopropanes. Part 7.1 Selenenylation and cyanoselenenylation of ethyl 2,2-dimethoxycyclopropanecarboxylates
作者:M. Liliana Graziano、M. Rosaria Iesce、Flavio Cermola、Giovanni Caputo、Fulvio De Lorenzo
DOI:10.1039/b109480g
日期:2002.2.22
1a. The presence of TiCl4 influences the stereochemistry of the reaction with chloride 3 while it is essential for reaction of the less reactive PhSeCN 4. With this electrophile the reactions lead to α,α-dimethoxycarbonitriles 13a–d while only 1a and 1b give also the expected cyanoselenenyl derivatives 12a and 12b. Moreover, from 1b compound syn- 5b is obtained, and 1a gives, via the alkene 2a, esters
C3取代的未催化反应 环丙烷 1b–d与苯硒烯基氯3生成1-乙基4-甲基2-(苯基硒代)丁二酸酯5b–d,而未取代的1a得到3-苯基硒代衍生物6a。的形成图5b-d发生区域选择性和立体选择性地通过的电开环1而图6a从的所述selenenylation结果烯烃 通过1a的异构化形成2a。TiCl 4的存在会影响与氯化物3的反应的立体化学,而这对于反应性较低的PhSeCN 4的反应必不可少。通过这种亲电试剂,反应生成α,α-二甲氧基腈13a-d,而只有1a和1b也给出了预期的氰基亚烯基衍生物12a和12b。此外,从图1b化合物顺-图5b中获得,和1a中给出,通过所述烯烃 2A,酯类 14a和6a。机理解释表明,稳定的偶极物质9的中间体应通过路易斯酸与碳酸的配位而形成。羰1的氧和随后的开环。