Reversal of .pi.-facial diastereoselection upon electronegative substitution of the substrate and the reagent
作者:Andrzej S. Cieplak、Bradley D. Tait、Carl R. Johnson
DOI:10.1021/ja00204a018
日期:1989.10
Les reactions examinees incluent les additions d'alkyllithiums, les oxymercurations, les osmylations et les epoxydations pour des cyclohexanones et des methylenecyclohexanes substitues
Les 反应受试者影响 les 加成 d'烷基锂、les oxymercurations、les osmylations 和 les 环己酮和亚甲基环己烷替代物的环氧基化
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
A systematic study of the diastereoselectivity of the radical carboazidation of methylenecyclohexane derivatives is presented. Several substitution patterns leading to a high level of stereocontrol have been identified. Axial attack is the preferred reaction pathway for cyclohexyl radicals, and excellent stereoselectivities can be obtained by introducing an axial substitutent at position 2. In this