Synthesis of novel polyhydroxylated quinolizidines: Ring expanded analogs of glycosidase inhibitory indolizidines

Abstract

Two polyhydroxylated quinolizidines, (1R,2R,3R,9S,9aR)-1,2,3,9-tetrahydroxyquinolizidine 9 and (1R,2R,3R,9R,9aS-1,2,3,9-tetrahydroxyquinolizidine 10, have been synthesized by the reductive double cyclization of 15[alpha] and 15[beta]. Quinolizidine 9 can be viewed either as a ring expanded analog of 6-epicastanospermine or of 8-episwainsonine, while 10 is a ring expanded analog of 1,6,8a-triepicastanospermine or of 8a-episwainsonine.