Synthesis of selenoxo peptides and oligoselenoxo peptides employing LiAlHSeH

Synthesis of selenoxo peptides by the treatment of N α- protected peptide esters with a combination of PCl 5 and LiAlHSeH is delineated. The method is simple, high-yielding, and free from racemization. Thus obtained selenoxo peptides are used as units for N-terminal chain extension through N α-deprotection/coupling to yield peptide-selenoxo peptide hybrids. Multiple selenation is demonstrated by conversion of two peptide bonds of tripeptides into selenoxo peptide bonds. Amino acid derived arylamides are also converted into aryl selenoamides. C 6H 5-CSeNH-Val-OMe 8f is obtained as single crystal, and its structure was determined through X-ray diffraction study. © 2012 American Chemical Society