ENANTIOSPECIFIC SYNTHESIS OF 1-DEOXYTHIOMANNOJIRIMYCIN FROM A DERIVATIVE OF D-GLUCOSE

1-Deoxythiomannojirimycin [2, 3S,4R,5S)-3,4,5-trihydroxy-2-hydroxymeth ylthiane], a thio analogue of the glycosidase inhibitor 1-deoxymannoji rimycin [1, R,5S)-3,4,5-trihydroxy-2-hydroxymethylpiperidine], has bee n synthesised from methyl benzoyl-4,6-O-benzylidene-alpha-D-glucoPyran oside. The key reactions involved inversion of configuration at C-2 wi th the introduction of a thio function and cyclisation to give methyl 2,6-anhydro-2-thio-alpha-D-mannopyranoside (12). Hydrolysis of the 3,4 -di-O-benzyl derivative (15) of 12 and reduction of the product with b orohydride gave S)-3,4-dibenzyloxy-5-hydroxy-2-hydroxymethylthiane (18 ). Hydrogenolysis of 18 yielded 2, which was a weak competitive inhibi tor of yeast alpha-D-glucosidase but was inactive against almond beta- D-glucosidase.