The preparation and oxyamination of 4,6-di- O-acetyl-2,3-dideoxy-α- d- erythro-hex-2-enopyranosyl 4,6-di- O-acetyl-2,3-dideoxy-α- d- erythro-hex-2-enopyranoside. Synthesis of two new diamino derivatives of α- d-mannopyranosyl α- d-mannopyranoside

Abstract

4,6-Di- O-acetyl-2,3-dideoxy- d- erythro-hex-2-enopyranose (4,6-di- O-acetyl- d-pseudoglucal), prepared from 3,4,6-tri- O-acetyl-1,5-anhydro-2-deoxy- d- arabino-hex-1-enitol (tri- O-acetyl- d-glucal), was condensed, by catalysis with boron trifluoride, with an equivalent of the original glycal, to give crystalline 4,6-di- O-acetyl-2,3-dideoxy-α- d- erythro-hex-2-enopyranosyl 4,6-di- O-acetyl-2,3-dideoxy-α- d- erythro-hex-2-enopyranoside in 40–50% yield. The dienic disaccharide was cis-oxyaminated with chloramine-T in the presence of osmium tetraoxide, furnishing in 72% yield an ∼2:3.5:1 mixture of the 2,2′-dideoxy-2,2′-di-( p-toluene-sulfonamido), 2,3′-dideoxy-2,3′-di-( p-toluenesulfonamido), and 3,3′-dideoxy-3,3′-di-( p-toluenesulfonamido) derivatives of α- d-mannopyranosyl α- d-mannopyranoside 4,6,4′,6′-tetraacetate. Separation of the mixture, achieved partly before and partly after O-deacetylation, was followed by high-yielding, reductive N-desulfonylations of the individual isomers with sodium in liquid ammonia, to give two new disaccharides, namely, 2-amino-2-deoxy-α- d-mannopyranosyl 2-1mino-2-deoxy-α- d-mannopyranoside and its 2,3′-diamino-2,3′-dideoxy isomer, and the known 3,3′-diamino-3,3′-dideoxy isomer. The amino sugars were isolated as their dihydrochlorides, and characterized further by preparation of their di- N-acetyl derivatives.