Aza-analogues of the repeating disaccharide unit of peptidoglycan. Part 2. Enantiospecific synthesis of peptide-derivatised 2-acetamido-4-O-(2′acetamido-2′-deoxy-β-D-glucopyranosyl)-3-O-carboxymethyl-1,2,5-trideoxy-1,5-imino-D-glucitol

Abstract

The L-alanyl-D-glutamic acid derivative 21, L-alanyl-D-glutamine derivative 23 and L-alanyl-γ-D-glutamyl-L-lysine derivative 25 of 2-acetamido-4-O-(2′-acetamido-2′-deoxy-β-D-glucopyranosyl)-3-O-carboxymethyl-1,2,5-trideoxy-1,5-imino-D-glucitol 2(X = OH) have been prepared as aza-analogues of the repeating disaccharide unit in bacterial cell wall peptidoglycan. The synthesis of methyl 5-azido-N-benzyloxycarbonyl-2,5,6-trideoxy-2,6-imino-3-O-(4-methoxybenzyl)-L-gulofuranoside 8α and the epimeric azide 9α from the corresponding D-mannofuranoside precursor 7α is described starting from a 1 : 1 anomeric mixture of the 2-O-(trifluoromethylsulfonyl)-D-glucofuranoside derivatives 4. Also reported are the subsequent transformations of the gulofuranoside 8α into the 2-azido-1,5-imino-D-glucitol 13 and the β-glycoside derivative 19 from which the three target aza-glycopeptides 21, 23 and 25 are prepared. None of the target compounds showed any antibacterial activity.