Synthesis of Functionalized Tetrahydropyridines by SnCl4‐Mediated Cycloaddition between Donor–AcceptorCyclobutanes and Nitriles

Cycloadditions of strained carbocycles promoted by Lewis acids are powerful methods to construct heterocyclic frameworks. In fact, the formal [3+2] cycloadditions of donor–acceptor (DA) cyclopropanes with nitriles has seen particular success in synthesis. In this work, we report on the first [4+2] cycloaddition of nitriles with DA cyclobutanes by Lewis acid activation. Tetrahydropyridine derivatives were obtained in up to 91 % yield from various aryl‐activated cyclobutane diesters and aliphatic or aromatic nitriles.