GENERATION OF ALPHA-ACETOXYGLYCINE RESIDUES WITHIN PEPTIDE CHAINS - A NEW STRATEGY FOR THE MODIFICATION OF OLIGOPEPTIDES

Seryl and threonyl peptides are converted into alpha-acetoxyglycyl peptides by treatment with lead tetraacetate. Reaction of these acetoxy derivatives or the more reactive alpha-chloroglycyl peptides with thiols, dithiols and carbohydrates allows the attachment of such units to peptide chains. The reaction of alpha-chloroglycyl peptides with amino acid esters and enamines proceeds with high stereoselectivity and yields peptides with N,N-acetal and (2-oxocyclohexyl)glycine moieties, respectively.