Cyclisations of 1,3-thiazine-2,4-diones and related systems

Thiazinediones 10 and 11 serve as starting materais for intramolecular amidoalkylations. While the stability of the derived hydroxy lactams14 and 15 is lower as compared to carbocyclic analogs the ring closures to the bicyclic systems indicate a common order of reactivity of the corresponding N-acyliminium intermediate, e.g. 26.