The formation of N-glycosidic linkage between N-acetylglucosamine (GlcNAc) and asparagine (Asn) was effected using aspartic acid gamma-fluoride in combination with either glycosyl azide or silyl carbamate, by the action of Lindlar catalyst or Bu4NF Further elongation of peptide chain was performed to give pentapeptide. This method was further applied into the synthesis of trisaccharidic asparagine, using beta-methoxybenzyl assisted stereoselective B-mannosylation as the key transformation. (C) 2000 Elsevier Science Ltd. All rights reserved.
L-aspartic acid bis(trimethylsilyl) ester: a convenient starting material for the acylation of L-aspartic acid.
作者:Ana M. Castano、Antonio M. Echavarren
DOI:10.1016/0040-4020(92)85013-5
日期:1992.1
Reaction of L-aspartic acid with excess of bis(trimethylsilyl)amine under reflux provides optically pure L-aspartic acid bis(trimethylsilyl) ester in quantitative yield. This silyl ester reacts with a variety of acylating reagens in tetrahydrofuran to give N-protected aspartic acids and dipeptides in good yields without racemization.