The synthesis of 3-amino-3-deoxy-α- d-glucopyranosyl α- d-glucopyranoside (3-amino-3-deoxy-α,α-trehalose

Abstract

The preparation of 2,3-di- O-benzoyl-4,6- O-benzylidene-α- d-glucopyranosyl-2- O-benzoyl-4,6- O-benzylidene-α- d- ribo-hexopyranosid-3-ulose ( 3) from 4,6:4′,6′-di- O-benzylidene-α,α-trehalose ( 1) via the 2,3,2′-tribenzoate 2 has been improved. Reduction of 3 with sodium borohydride gave 2- O-benzoyl-4,6- O-benzylidene-α- d-allopyranosyl 2,3-di- O-benzoyl-4,6- O-benzylidene-α- d-glucopyranoside ( 4), which was converted into the methanesulfonate 5 and trifluoromethanesulfonate 6. Displacement of the sulfonic ester group in 6 with lithium azide was very facile and afforded a high yield of 3-azido-2- O-benzoyl-4,6- O-benzylidene-3-deoxy-α- d-glucopyranosyl 2,3-di- O-benzoyl-4,6- O-benzylidene-α- d-glycopyranoside ( 7), whereas similar displacement in 5 proceeded sluggishly, giving a lower yield of 7 together with an unsaturated disaccharide ( 8). The azido sugar 7 was converted by conventional reactions into the analogous 2,3,2′-triacetate 9, the corresponding 2,3,2′-triol 10, and deprotected 3-azido-3-deoxy-α- d-glucopyranosyl α- d-glucopyranoside ( 11). Hydrogenation of 11 over Adams' catalyst furnished crystalline 3-amino-3-deoxy-α,α-trehalose hydrochloride ( 12), the overall yield from 3 being 35%.