Abstract
The activation of delta-valerolactam with triflic anhydride is studied in detail. Triflic anhydride activation initially produces the O-triflated lactam I, which rearranges, following the addition of base, to the N-triflated derivative II. Increasing temperatures favour this triflate group migration, but only when a base is present. On reaction with a suitable nucleophile, the lactam ring is opened resulting in an acyclic product. The N-triflated derivatives have been reacted with a range of nucleophiles to produce esters and amides, which are formally dipeptides of o-amino acids. In addition, a synthetic pathway to 1,3,4-oxadiazole based dipeptide mimetics has been worked out starting from commercially available Boc-protected amino acids IV. This synthetic route improves on a published method for producing these types of compound, both in simplicity and yield of final compound. This route has been successfully used to synthesise novel hydrazide intermediates V and 1,3,4-oxadiazole products VI.