Tandem 1,5-Hydride Shift/6π Electrocyclization of Ketenimines and Carbodiimides Substituted with Cyclic Acetal and Dithioacetal Functions: Experiments and Computations
beneficial effect of the acetal function, which gives hydride character to the migrating hydrogen atom. The capability to promote the H shift depends on the type of acetal function (acetal better than dithioacetal), its ring size (five-membered better than six-membered) and the heterocumulenic fragment (ketenimine better than carbodiimide). Changing the benzene ring connecting the acetal and ketenimine functions