Extractives of Australian timbers. XV. The synthesis of 7,4'-Di-O-methylbayin

Abstract

The reaction between 2,6-dimethoxyphenylmagnesium bromide and tetraacetyl-α-D- glucosyl chloride gave mainly α-D-glucopyranosyl-2,6-dimethoxybenzene (8) and the β-isomer (9). The a-isomer (8) was readily converted by acids into the /?-isomer (9), whose structure was confirmed by comparison with authentic material prepared by the degradation of 7,4?-di-O-methylbayin. The reaction of the tetraacetate of (9) with acetyl chloride in the presence of anhydrous aluminium chloride gave 3-β-D-glucopyranosyl-2-hydroxy-4-methoxyacetophenone (11). Condensation of (11) with p-methoxybenzaldehyde gave the chalcone (15) which, on reaction with selenium dioxide, formed 7,4?-di-O-methylbayin (8-C-β-D- glucopyranosyl-7,4?-dimethoxyflavone) (5).