Methyl 6-azido-4-O-benzyl-6-deoxy- (5) and methyl 6-azido-4-O- (p-bromobenzyl)-6-deoxy- α-D -mannopyranoside (6) were obtained by reaction of methyl 4-O-benzyl- (1) and methyl 4-O-(p-bromobenzyl)- 2,3-O-isopropylidene-6-O-toluene-sulfonyl-α-D-mannopyranoside (2) with sodium azide, followed by acid hydrolysis. Selective benzylation andp-bromobenzylation of 5 and 6 under phase transfer conditions afforded methyl 6-azido-2,4-di-O-benzyl-6-deoxy- (7) and methyl 6-azido-2,4-di-O-(p-bromobenzyl)-6-deoxy-α-D-mannopyranoside (8) respectively, which were acetylated and subsequently chlorinated to give 3-O-acetyl-6-azido-2,4-di-O-benzyl-6-deoxy- (11) and 3-O-acetyl-6-azido-2,4-di-O-(p-bromobenzyl)-6-deoxy-α-D-mannopyranosyl chloride (12). Ring closure of 11 and 12 was conducted in the presence of potassiumtert-butoxide to give the title anhydro sugar ethers in almost quantitative yield. The full assignments of1H and13C NMR spectra of the anhydro sugar ethers were achieved by single frequency decoupling and1H-13C two-dimensional heteronuclear correlated NMR spectroscopy. Vicinal and long-range proton-proton coupling constants suggested that the conformations of the 1,3-anhydro sugar ethers are essentially B2,5(D) for the pyranose rings and chairs for the 1.3-dioxane rings.