N‐Heterocyclic Carbene‐Catalyzed Diastereoselective Radical Ring Opening of Bicyclobutanes to 1,1,3,3‐Tetrasubstituted Cyclobutanes

Herein, the N‐heterocyclic carbene (NHC) catalyzed ring opening of bicyclo[1.1.0]butanes (BCBs) with aldehydes and Togni I reagents through a three‐component radical relay process is reported, which affords 1,1,3,3‐tetrasubstituted cyclobutanes. This reaction exhibits exclusive regioselectivity and up to excellent diastereoselectivity under mild and operating‐simple conditions. Gram‐scale synthesis and several product derivatizations demonstrate their potential utilities as versatile building blocks in synthetic chemistry.