Diastereoselective synthesis of the benzoxazinone acetal glucoside ent-GDIMBOA: the first enantiomer of a natural acetal glucoside

The synthesis of (2S)-2-β-l-glucopyranosyloxy-4-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one, the enantiomer of the natural acetal glucoside GDIMBOA from maize, has been achieved by the double diastereoselective l-glucosylation of racemic 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one with 2,3,4,6-tetra-O-acetyl-β-l-glucopyranosyl trichloroacetimidate in the presence of excess of boron trifluoride etherate as promoter as well as protecting and equilibrating agent.