A novel and facile synthesis of azaspiro-γ-lactones with a methylene-lactam framework from N-carbonyl imides is described. Mechanistic investigations provide evidence for a two-step reaction process involving ZnCl(2)-promoted addition of β-amido allylindium species followed by an unexpectedly molecular-sieves-mediated ring opening-reclosure concomitantly with the loss of an N-carbonyl unit.

The novel facile approach provides a new class of succinimide or phthalimide--derived azaspiro--lactones with an exo-methylene lactam ring as potential drug candidates. -(SENGOKU, T.; MURATA, Y.; ASO, Y.; KAWAKAMI, A.; INUZUKA, T.; SAKAMOTO, M.; TAKAHASHI, M.; YODA*, H.; Org. Lett. 17 (2015) 23, 5846-5849, http://dx.