α,α-DICHLOROISOXAZOLIDINONES FOR THE SYNTHESIS AND CHEMOSELECTIVE PEPTIDE LIGATION OF α-PEPTH)E α-KETOACIDS

摘要

In seeking to develop an iterative approach to the preparation of α-oligopeptides by the chemoselective amide-forming coupling of α-ketoacids and hydroxylamines, we have designed and synthesized novel enantiopure monomers. Key to our approach is the use of α,α-dichloroacids as masked a-ketoacids. The preparation of these monomers, their coupling with a-ketoacids, and the conversion of the α,α-dichloroacids to a-ketoacids is described. These studies provide a first step to a conceptually unique approach to peptide synthesis that does not require activating reagents or produce chemical byproducts.