Process for the preparation of tetrahydroindolizines

摘要

Described is a process for the preparation of Compound (7) in accordance with the following reaction scheme by reacting Compound (5) with ethylene glycol in a solvent in the presence of a Lewis acid, thereby obtaining Compound (6), and then reacting the resulting compound with a carbonate diester in a solvent in the presence of a metal alkoxide (R1, R6 each represents a C1-6 alkyl group or the like and R5 represents H or C1-5 alkyl group).Compound (7) so obtained is useful as an intermediate for camptothecins useful as antitumor agents.