Azidation of β-carbonyl lactones and lactams

The direct azidation of various heterocyclic β-ketoesters, lactones, and lactams is reported. By using tosylazide and an organic base such as l-proline or TBD, the direct α-insertion of azide into these substrates was achieved in moderate to good yields, without competitive deacylating diazo transfer. This procedure represents an interesting alternative to the usual two-step approach of α-halogenation and subsequent displacement with azide ion.