Ritter-type reaction of C-(1-bromo-1-deoxy-d-glycopyranosyl)formamides and its application for the synthesis of oligopeptides incorporating anomeric α-amino acids Original Research Article

O-Peracetylated or -perbenzoylated C-(1-bromo-1-deoxy-d-glycopyranosyl)formamides of d-gluco, d-galacto, and d-arabino configuration were reacted with Ag(I)-salts or HgO in nitrile solvents to give N-acyl-1-cyano-d-glycopyranosylamines with an axial C–N bond at the anomeric centre. In the presence of HgBr2, Hg(CN)2, or InCl3 the anomer of the above glycosylamine with an equatorial C–N bond was also isolated or detected. In CH3NO2 solutions as few as 5–10 equiv of the nitrile were sufficient to get acceptable yields for the products. Under similar conditions N-substituted C-(2,3,4,6-tetra-O-acetyl-1-bromo-1-deoxy-β-d-galactopyranosyl)formamides gave anomeric spiro-oxazoline derivatives which, upon mild acidic hydrolysis, opened up to di- and tripeptides of anomeric α-amino acids.