Enantioselective total synthesis of (−)-indolizidines 209B and 209D via a highly efficient aza-[2,3]-wittig rearrangement of vinylaziridines

Abstract

A novel protocol for the enantioselective synthesis of (−)-indolizidines 209B ( 2) and 209D ( 1) is described, in which the key step is the highly efficient aza-[2,3]-Wittig rearrangement of vinylaziridines 11a,b into tetrahydropyridines 12a,b. Functional group manipulation and chain elongation then gave esters 16a,b which were converted to the target alkaloids via lactams 17a,b.