title: Crossed Intermolecular [2+2] Cycloaddition of Styrenes by Visible Light Photocatalysis.
abstract: We report a method for the crossed [2+2] cycloaddition of styrenes using visible light photocatalysis. Few methods for the synthesis of unsymmetrically substituted cyclobutanes by photochemical [2+2] cycloaddition are known. We show that careful tuning of the electrochemical properties of a ruthenium photocatalyst enable the efficient crossed [2+2] cycloaddition of styrenes upon irradiation with visible light. We outline the logic that enables high crossed chemoselectivity, and we also demonstrate that this reaction is remarkably efficient; gram-scale reactions can be conducted with as little as 0.025 mol% of the photocatalyst.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, WI 53706, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Ischay
authors.forename: Michael S
authors.initials: MS
authors.lastname: Ament
authors.forename: Tehshik P
authors.initials: TP
authors.lastname: Yoon