Syntheses and absolute structures of the disaccharide and aglycone of acaricidal gualamycin.

Gualamycin is a water-soluble acaricide isolated from the culture broth of Streptomyces sp. NKl^S?1*. The structure was deduced to be 1 mainly from the spectral and/or X-ray crystallographic analyses of its disaccharide 2 and aglycone portions 32). The absolute structure of the disaccharide, however, remained undetermined. Herein, we confirm the absolute structure 1 by the enantiospeciflc syntheses of the disaccharide 2 and aglycone derivatives 3. When considered the molecular rotation ([a]D + 276°)1} of the acetylated disaccharide 2 in comparison with those of acetylated methyl 2-amino-2-deoxy-/?-Dand L-gulopyranosides3) and methyl oc-dand L-galactopyranosides4) according to Hudson's rule5), the disaccha-