摘要:
Moderate stereocontrol in 5-exo radical cyclizations of N,N-disubstituted (-)-8-amino menthol derivatives, promoted by tributyltin hydride and AIBN, was achieved. The stereoselection was explained in terms of hydrogen bond formation in the 1,3-amino alcohol derivative. The presence of one additional stereocenter at the allylic chain enhanced the stereoselection giving a single cyclization stereoisomer. The cyclization products were easily converted into enantiopure 5-alkyl- or 2,3-dialkyl-substituted pyrrolidines.