Total Synthesis of Coumarinolignans, Aquillochin (Cleomiscosin C) and Cleomiscosin D

Abstract

The reaction of 8-hydroxy-6-methoxy-7-methoxymethoxycoumarin (3) with ethyl 2-bromo-3-(4-benzyloxy-3, 5-dimethoxypheny1)-3-oxopropionate (5) in the presence of potassium tert-butoxide gave the condensation product (6), which, on treatment with hydrochloric acid followed by reduction with lithium borohydride, was converted into a diastereomeric mixture of alcohols (8a, b). Treatment of the alcohols (8a, b) with 35% hydrochloric acid in acetic acid furnished aquillochin (cleomiscosin C)(1). The regioisomer cleomiscosin D (2) was similarly synthesized from 10.