SYNTHESIS OF BENZOXAZINOID ACETAL GLUCOSIDES NATURALLY-OCCURRING IN GRAMINEAE

Benzoxazinoid acetal glucosides, a unique class of natural hemiacetal ethers from Gramineae and other species, are of interest as precursors of aglucones which exhibit high bioactivity as plant resistance facto rs against microbial diseases and insects, allelo chemicals and endoge neous ligands. This review gives a survey on synthetic methods which g ive rise to the hemiacetalic aglucones of the 2-hydroxy-2H-1, 4-benzox azin-3(4H)-one skeleton, efficiently. As a result of investigations in the area of acetal glucosidation a double diastereoselective glucosid ation method of racemic cyclic hemiacetals has been developed that aff ords an access to the acetal glucosides of natural configuration as we ll as to their enantiomers.