On the activation of valerolactam with triflic anhydride: the synthesis of omega-trifluorosulfonamido dipeptides using a transpeptidation reaction under mild conditions.

The activation of valerolactam with triflic anhydride is studied in detail, initially producing an O-triflated lactam, which rearranges, following the addition of base at higher temperatures, to an N-triflated derivative. This reacts with a series of nucleophiles to produce esters and amides, which are formally dipeptides of omega-amino acids.