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The first diastereoselective syntheses of the natural acetal glucosides, (2R)-2-β-d-glucopyranosyloxy-4-hydroxy-2H-1,4-benzoxazin-3(4H)-one and (2R)-2-β-d-glucopyranosyloxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one, are described by reaction of O-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl) trichloroacetimidate with hemiacetalic aglucones of the 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one skeleton.

The absolute configurations of 2- O -β- D -glucopyranosyl-7-methoxy-1,4(2H)-benzoxazin-3-one and three congeners isolated from Coix lachryma-jobi var. ma-yuen were determined by X-ray analysis and chemical correlation as the 2 R type. 13 C NMR spectra of all congeners and coixol were fully assigned.