Substituent effects on 2-aza-5-hexynyl radical cyclization regiochemistry
作者:Joong-Kwon Choi、David J. Hart、Yeun-Min Tsai
DOI:10.1016/s0040-4039(00)85708-1
日期:1982.1
Cyclizations of several N-acyl-2-aza-5-hexynyl radicals are described. The regiochemical course of these cyclizations depend on the nature of substituents at the alkyne terminus.
Free radical cyclizations in alkaloid synthesis: (+)-heliotridine and (+)-hastanecine
作者:Joong-Kwon Choi、David J. Hart
DOI:10.1016/s0040-4020(01)97176-5
日期:1985.1
hydride and AIBN affords mixtures of reduction and cyclization products. Cyclization products partition between indolizidinones and pyrrolizidinones depending on the terminal alkyne substituent. When the terminal substituent is a trimethylsilyl group, synthetically useful yields of pyrrolizidinones are obtained. Applications of this chemistry to the synthesis of (+)-heliotridine (2) and (+)-hastanecine (3)