New Cascade Processes on Group 6 Fischer-Type Carbene Complexes: Cyclopropanation and Metathesis Reactions
摘要:
Alkynyl Fischer carbene complexes 1, which feature a pendant olefin group, undergo novel cascade processes triggered by [2+2], [3+2], and [4+2] cycloadditions. Competition between cyclopropanation and olefin metathesis is controlled by the substitution at the double bond. The method described can be used to obtain different kind of polycarbo- and -heterocycles. A mechanistic explanation by means of DFT computational modeling is provided.
Gold Catalysis: Synthesis of 3-Acylindenes from 2-Alkynylaryl Epoxides
作者:A. Stephen K. Hashmi、Miriam Bührle、Ralph Salathé、Jan W. Bats
DOI:10.1002/adsc.200800385
日期:2008.9.5
A series of 2-alkynylarylepoxides were prepared by a sequence of Sonogashira coupling, Wittig olefination and epoxidation or a Darzens’ glycid ester synthesis. The conversion of these substrates with gold(I) catalysts furnished 3-acylindenes and, in occasional cases as side-products, the products of an isomerization of the oxirane ring to a ketone. Isotope labelling of the epoxide oxygen indicates