Abstract
A new synthesis of (±)-9-demethylmunduserone (2) is described. Thermal rearrangement of 1-(4-benzyloxy-2-hydroxyphenyl)-4-(3', 4'-dimethoxyphenoxy)-2-butyn-l-one (7) afforded 4-(4-benzyloxy-2-hydroxybenzoyl)-6, 7-dimethoxy-2H-chromene (8), 3-(4-benzyloxy-2-hydroxybenzoyl)-5, 6-dimethoxy-2-methylbenzofuran (9) and 9-benzyloxy-2, 3-dimethoxy-6a, 12a-dihydrorotoxen-12 (6H)-one (3). 4-Aroyl-2H-chromene (8) was smoothly converted to 3 in quantitative yield by the treatment with sodium acetate. The structure of 3 was con-firmed by an alternative synthesis from methyl tephrosate (10). Debenzylation of 3 with aluminum bromide afforded (±)-9-demethylmunduserone (2) in high yield.
