Studies on the C-alkylation and C-allylation of small peptides employing glycyl radical intermediates

Abstract

A series of dipeptides and one tripeptide possessing a glycyl xanthate unit has been employed as an alternative method for the introduction of side chains directly onto a peptide chain. Two non-metal-based radical reactions are examined, involving either the addition of the glycyl xanthate unit onto an alkene or an allylation procedure employing allyl alkyl sulfones. These procedures are advantageous as they avoid the use of the toxic but more common tinhydride-based compounds. Variable yields for the side-chain introduction are observed with best results for the dipeptides. Attempts are also made to adapt the allylation protocol to the direct side-chain introduction on a non-functionalised glycine unit.