Michael Addition−Elimination Mechanism for Nucleophilic Substitution Reaction of Cycloalkenyl Iodonium Salts and Selectivity of 1,2-Hydrogen Shift in Cycloalkylidene Intermediate
作者:Morifumi Fujita、Wan Hyeok Kim、Koji Fujiwara、Tadashi Okuyama
DOI:10.1021/jo049218k
日期:2005.1.1
of allylic and vinylic forms. Deuterium-labeling experiments show that the allylic product is formed via the Michael addition of cyanide to the vinylic iodonium salt, followed by elimination of the iodonio group and 1,2-hydrogen shift in the 2-cyanocycloalkylidene intermediate. The hydrogen shift preferentially occurs from the methylene rather than the methine β-position of the carbene, and the selectivity
环己烯基和环戊烯基碘鎓盐与氰化物离子在氯仿中的反应生成烯丙基和乙烯基形式的氰化物取代产物。氘标记实验表明,烯丙基产物是通过将氰化物迈克尔加成到乙烯基碘鎓盐中,然后消除2-氰基环亚烷基中间体中的碘基团和1,2-氢转移而形成的。氢转移优先发生在卡宾的亚甲基而不是次甲基的β-位,并且选择性通过DFT计算得以合理化。在环戊烯基碘鎓盐与乙酸根离子在氯仿中的反应中也观察到迈克尔反应。的乙烯基取代产物归因于配体偶联(经由λ 3-碘)和消除加成(通过环己炔)途径。