pound (11). the primary C-6 mesyloxy group can be S O ~V Olyzed selectively: sodium azide in dimethylformamide (3 h, 75 "C) gives the 6-azido compound (12) [m.p. 148-150 "C, [a];5 = +162 ( c = 1, CHCI3), yield 84 %I; similarly, sodium benzoate in dimethylformamide (5h, 80 "C) gives analytically and chromatographically 6 1 pure methyl 2,3,6-tri-O-benzoyl-4-O-mesyl-c~-~-glucopyranosyl (13) in amorphous form [[. I' d = +139 (c = 1, CHC13), yield 92 %]. Solvolysis of the C-4 mesyloxy group in (13) by heating with sodium azide in dimethylformamide (60 h, 100 "C) and subsequent de-0benzoylation with methanolic ammonia affords methyl 4azido-4-deoxy-a-~-galactopyranoside (61, R = H [m.p. 153-155 "C, [a12 = +120° (c = 0.5, CH3OH), yield 64 741.
Hydrogenation of (61, R = H , followed by N-acetylation yields a product whose melting point, [ a ] ~, and IR spectrum are identical with those of (10).
The galacto configuration of ( I ) and (S)-(IO) follows from the method of preparation [6bl and from N M R spectroscopic data. The acetyl resonances obtained for ( I ) [T = 7.91, 7.94 (2). and 8.01 in CDC13; 7.96, 7.98, and 8.08 (2) in [D6]-DMSO] indicate171 the absence of axial acetoxy and equatorial acetylamino groups. Analysis of the ring C H protons effected at 100 MHz in CDC13 [81 gave for H-4 at T = 5.27 a quartet with J34 = 4.0 and J4NH = 10.0 Hz, each line being broadened by coupling with H-5 (J45 = 1 Hz). This quartet is simplified to a 4-Hz doublet by irradiation at the resonance frequency of the N H doublet (T = 3.61, 10 Hz) and to a 10 H z doublet by irradiation at the resonance frequency of the H-3 quartet (T = 4.72).
Attempts t o obtain (2) by acid hydrolysis of ( I ) o r (10) 14 N HCI, 100 "C] and subsequent N-acetylation have so far failed. Apparently ring contraction giving the pyrrolidine sugar occurs under the conditions necessary for glycoside cleavage 191.