Asymmetric O-methylhalohydrin reaction of chiral N-enoyl-2-oxazolidinones: synthesis of N-protected syn-β-methoxyphenylalanine, an unusual amino acid component of cyclomarins

Asymmetric O-methylhalohydrin reactions of chiral N-enoyl-2-oxazolidinones were performed with halogens (Br2/I2) promoted by silver(I) in methanol with high regio- and anti-selectivity and moderate to good diastereoselectivity. Reagent-controlled opposite diastereoselectivity was observed especially for cinnamoyl and electron-deficient cinnamoyl substrates. This method was applied to the short enantioselective synthesis of N-protected syn-β-methoxyphenylalanine, an unusual amino acid component of cyclomarins.