Sterically and Temperature Controlled Divergent Cycloadditions of α,β‐Unsaturated Imines with Vinylethylene Carbonates: Insights from Experimental and DFT Studies

Abstract Divergent synthesis of heterocycles with controllable ring sizes from the same starting materials is a long‐standing challenge. We report herein the first example of controllable divergent [4+5] and [2+3] cycloadditions of α,β‐unsaturated imines and vinylethylene carbonates, which enables the selectively synthesis of nine‐membered and different five‐membered heterocycles by controlling the reaction temperature and the steric hindrance of substituent. This protocol features a broad substrate scope, wide functional group tolerance as well as operational simplicity. The reaction mechanism was investigated by con‐ducting a series of control experiments as well as DFT calculations and the origins of the regioselectivities of the cycloaddition process were rationalized. magnified image