SYNTHESES OF BETA-MANNOPYRANOSIDES BY ENZYMATIC APPROACHES

The transmannosylation activity of beta-mannosidase from snail and bet a-galactosidase from Aspergillus oryzae was used for the synthesis of methyl, ethyl, 1-propyl, 2-propyl, 1-butyl, 2-butyl, 1-hexyl, cyclohex yl, and 1-octyl beta-D-mannopyranosides (3a-i), respectively. The regi oisomeric specificities and wide substrate acceptance of this galactos idase are demonstrated. Thus, 4-nitrophenyl -O-(alpha-D-glucopyranosyl )-beta-D-glucopyranoside (6), 4-nitrophenyl 2-O-(O-D-glucopyranosyl)-b eta-D-glucopyranoside (7), 4-nitrophenyl etyl-beta-D-glucopyranosyl)-b eta-D-glucopyranoside (8), 4-nitrophenyl -O-(beta-D-mannopyranosyl)-al pha-D-mannopyranoside (9), and 4-nitrophenyl 4-O-(beta-D-mannopyranosy l)-beta-D-mannopyranoside (10) were prepared by chemoenzymatic self-tr ansfer reaction.