5,6-dihydroindolizines as convenient precursors of Indolizidine 167B and analogues

Starting from 5-carboxyethyl-5,6-dihydroindolizine, the title alkaloid was obtained in 25% overall yield via differently C5-substituted 5,6-dihydroindolizines and final exhaustive hydrogenation. An alternative strategy for the synthesis of optically active indolizidine 167B and analogues still based on 5,6-dihydroindolizine intermediates is given. © Georg Thieme Verlag Stuttgart