Reactions of Methyl threo-2-Acetoxy-3-chloro-3-(4-methoxyphenyl)propanoate and Methyl cis-2,3-Epoxy-3-(4-methoxyphenyl)propanoate With 3,5-Dimethoxyphenol: Potential Routes to Flavan-3-ols

Abstract

Attempted syntheses of flavan-3-ols by reaction of either methyl threo-2-acetoxy-3-chloro-3-(4-methoxypheny1)propanoate (3) or methyl cis-2,3-epoxy-3-(4-methoxypheny1)propanoate (14) with 3,5-dimethoxyphenol failed to give the required aryl ethers. Products usually were derived from C-alkylation of the electron-rich phenol although reaction of the chloro acetate (3) with the phenoxide ion gave the furanone (5). The single-crystal X-ray structures of methyl 4-hydroxy-3-(4-methoxyphenyl)-2-(4-methoxyphenylmethyl)-5-oxo-2,5-dihydrofuran-2-carboxylate and cis-3-hydroxy-5,7-dimethoxy-4(4-methoxyphenyl)-3,4dihydr-2H-1-benzopyran-2-one have been determined.