Title

Enantioselective [2+2] Cycloadditions of Cinnamate Esters: Generalizing Lewis Acid Catalysis of Triplet Energy Transfer

ACS Citation

Daub, M. E.; Jung, H.; Lee, B. J.; Won, J.; Baik, M.-H.; Yoon, T. P. Enantioselective [2+2] Cycloadditions of Cinnamate Esters: Generalizing Lewis Acid Catalysis of Triplet Energy Transfer. J. Am. Chem. Soc., 2019, 141, 9543–9547.

Abstract

We report the enantioselective [2+2] cycloaddition of simple cinnamate esters, the products of which are useful synthons for the controlled assembly of cyclobutane natural products. This method utilizes a cocatalytic system in which a chiral Lewis acid accelerates the transfer of triplet energy from an excited-state Ir(III) photocatalyst to the cinnamate ester. Computational evidence indicates that the principal role of the Lewis acid cocatalyst is to lower the absolute energies of the substrate frontier molecular orbitals, leading to greater electronic coupling between the sensitizer and substrate and increasing the rate of the energy transfer event. These results suggest Lewis acids can have multiple beneficial effects on triplet sensitization reactions, impacting both the thermodynamic driving force and kinetics of Dexter energy transfer.

Source Name

Journal of the American Chemical Society

Publication Date

2019

Volume

141

Page(s)

9543–9547

Document Type

Citation

Citation Type

Article

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