New Diacylamino Protecting Groups for Glucosamine

Glucosamine was transformed into N-diphenylmaleoyl (DPM), N-(3,3-dimethylglutaryl) (DMG), and N-diglycolyl (DG) derivatives which furnished O-acetyl-protected O-glycosyl trichloroacetimidates 3, 12, and 20, respectively, as glycosyl donors. Their reactions with various acceptors 4 in the presence of TMSOTf as catalyst afforded the corresponding β-glycosides 5a–c, 13a–e, and 21a,d,f,g generally in high yields. Investigations into the cleavage of the N-protecting groups led to good results for the DPM and DG groups. 3-O-Unprotected glucosamine derivative 24 with N-DG protection also served well as an acceptor, as shown in its reaction with galactosyl donor 25 which led to disaccharide 26 in very high yield. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)