Selective protections on 2-allyloxycarbonylamino-1,6-anhydro-2-deoxy-β- d-glucopyranose

Abstract

Regioselective monoacetylation of 2-allyloxycarbonylamino-1,6-anhydro-2-deoxy-β- d-glucopyranose ( 1) gave a mixture of 3- O-acetyl and 4- O-acetyl derivatives, the structures of which were estabished by two-dimensional, phase-sensitive NOESY and confirmed by chemical proofs. The benzylation of 1, on the other hand, led to 2-allyloxycarbonylamino-1,6-anhydro-3,4-di- ( 5) or 2-allyloxycarbonylamino-1,6-anhydro-2 - N-benzyl-3,4-di- O-benzyl-2-deoxy-β- d-glucopyranose ( 10). The regioselective cleavage of 5 with titanium tetrachloride gave the expected 3- O-benzyl derivative, the structure of which was ascertained by chemical proofs; the same reaction performed on 10 led to the opening of the anhydro ring to afford 3-benzyl-[3,4-di- O-benzyl-1,2-dideoxy-α- d-glucopyrano]-[2,1-d]-2-oxazolidone.