Lewis-Base-Catalyzed Annulations of Nitroallylic Acetates as C3 Synthons with Electron-Deficient Alkenes

Abstract

2-Nitroallylic acetates have been demonstrated to be versatile C3 synthons in Lewis-base-catalyzed annulation reactions. Catalyzed by PhPMe2 (20mol%), they readily undergo a cascade [3+2] annulation/allylic alkylation reaction with electron-deficient alkenes to provide cyclopentenes and even spirocyclopenteneoxindoles in moderate to good yields and high diastereoselectivity. Under the catalysis of 4-dimethylaminopyridine (20mol%), 2-nitroallylic acetates also undergo a [3+3] annulation reaction with 1,1-dicyanoalkenes to give cyclohexenes. This work further broadens the scope of the Lewis-base-catalyzed annulation protocol for modified allylic derivatives.