SYNTHESIS OF 2-AMINO-2-DEOXY AND 3-AMINO-3-DEOXY-ALPHA-D-MANNOPYRANOSYL ALPHA-D-MANNOPYRANOSIDE BY SEQUENTIAL OSMYLATIONS OF A DIENIC DISACCHARIDE

Partial oxyamination of 4,6-di-O-acetyl-2,3-dideoxy-.alpha.-D-erythro-hex-2-enopyranosyl 4,6-di-O-acetyl-2,3-dideoxy-.alpha.-D-erythro-hex-2-enopyranoside with chloramine-T and osmium tetraoxide gave 4,6-di-O-acetyl-2-deoxy-2-(p-toluene-sulfonamido)-.alpha.-D-mannopyranosyl 4,6-di-O-acetyl-2,3-dideoxy-.alpha.-D-erythro-hex-2-enopyranoside and its 3-deoxy-3-(p-toluenesulfonamido) regioisomer, each in 18-19% isolated yield. Osmium tetraoxide-catalyzed cis-hydroxylation of the remaining alkenic residue in these products led in high yields to the corresponding triols having the .alpha.-D-manno, .alpha.-D-manno configuration. These were N-desulfonylated (and simultaneously O-deacetylated) by the action of sodium in liquid ammonia to furnish 2-amino-2-deoxy-.alpha.-D-mannopyranosyl .alpha.-D-mannopyranoside and 3-amino-3-deoxy-.alpha.-D-mannopyranosyl .alpha.-D-mannopyranoside as new, trehalose-type amino sugars.