Regulatory Mechanism of the Enantioselective Intramolecular Enone [2+2] Photocycloaddition Reaction Mediated by a Chiral Lewis Acid Catalyst Containing Heavy Atoms

• Published in: Angewandte Chemie International Edition Vol. 54; no. 48; pp. 14295 - 14298
• Main Authors: Wang, Hongjuan, Cao, Xiaoyan, Chen, Xuebo, Fang, Weihai, Dolg, Michael
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 23.11.2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: ab initio calculations; Atoms & subatomic particles; Catalysis; Catalysts; cycloaddition; Enantiomers; enantioselectivity; heterocycles; Lewis acid; Lewis acids; Pseudopotentials; Quantum chemistry; Regulatory mechanisms (biology); Relativism; Relativistic effects; Spin-orbit interactions; ab initio calculations; enantioselectivity; Lewis acids; cycloaddition; heterocycles
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201505931

The asymmetric catalysis of the intramolecular enone [2+2] photocycloaddition has been subject of extensive experimental studies, however theoretical insight to its regulatory mechanism is still sparse. Accurate quantum chemical calculations at the CASPT2//CASSCF level of theory associated with energy‐consistent relativistic pseudopotentials provide a basis for the first regulation theory that the enantioselective reaction is predominantly controlled by the presence of relativistic effects, that is, spin–orbit coupling resulting from heavy atoms in the chiral Lewis acid catalyst. Going for a spin: Ab initio calculations at the CASPT2//CASSCF level of theory show that the enantioselective enone [2+2] photocycloaddition (PCA) reaction is predominantly controlled by an enhanced spin–orbit coupling of the heavy atoms in the chiral Lewis acid catalyst. These mechanistic insights provide useful benchmarks for further studies of PCA reactions mediated by Lewis acids.