Synthesis of 5'(S)-1,1-dioxolane-5-oxo-(5'-ethyl-5'-hydroxyl-2'H,5'H,6'H-6-oxopyrano)-[3',4'-f]-Δ~(6(8))-tetrahydroindolizine

Aim To synthesize 5'(S)-1,1-dioxolane-5-oxo-(5'-ethyl-5'-hydroxyl-2'H,5'H,6'H-6-oxopyrano)-[3',4'-f]-Δ6(8)-tetrahydroindolizine,a key intermediate for the total synthesis of anticancer drugs 20(S)-camptothecin and its deriveatives.Methods Target compound was synthesized from 1,1-dioxolane-5-oxo-(5'-ethyl-2'H,5'H,6'H-6-oxopyrano)-[3',4'-f]-Δ6(8)-tetrahydroindolizine,via a three-step process including iodine catalyzed oxidation,kinetic resolution and base-hydroxylation.Results and conclusion The synthetic procedure was simple to manipulate and the target compound is obtained with ee 96% optical purity in 15.7% overall yield.