Regio- and Diastereoselective Intermolecular [2+2] Cycloadditions Photocatalyzed by Quantum Dots

Here we show that colloidal quantum dots serve as visible-light chromophores, photocatalysts, and resuable scaffolds for homo- and hetero-intermolecular [2+2] photocycloadditions of 4-vinylbenzoic acid derivatives, with >90% tunable regioselectivity and up to 98% diastereoselectivity for the previously minor syn-cyclobutane products, including the syn-heda-to-tail cyclobutane, which has never been produced as the major product of a photochemical reaction.