New Methylene Homologation Method for Cyclic Ketones
作者:Huaqing Liu、Chunrui Sun、Nam-Kyu Lee、Roger F. Henry、Daesung Lee
DOI:10.1002/chem.201201346
日期:2012.9.17
Teaching new tricks to an old dog: By intercepting adducts between ketones and lithium trimethylsilyldiazomethane, a new Tiffeneau–Demjanov type methylenehomologation could be realized in a single‐step operation. Among proton sources and Lewis acids, silica gel was found to be the most effective reagent for the protonation of intermediates and their subsequent ring expansion (see scheme).
Alkyl radical cyclisations of methylenecyclopropane derivatives
作者:Christine Destabel、Jeremy D Kilburn、John Knight
DOI:10.1016/s0040-4020(01)89429-1
日期:1994.1
Radical cyclisations of various methylenecyclopropane derivatives have been studied. Cyclisation of diphenylsubstituted (methylenecyclopropyl)butyl radical 10 gave the unexpected cyclohexene 5, via a series of radical rearrangements. In further studies, (methylenecyclopropyl) radicals underwent exclusive 5-exo cyclisation, while (methylenecyclopropyl)butyl radicals gave mixtures of products resulting