Visible light photocatalysis of intramolecular radical cation Diels-Alder cycloadditions

Intramolecular radical cation Die Is-Alder reactions can be conducted under photocatalytic conditions using visible light irradiation. The photocatalyst system involves the use of a Ru(bpy)(3)(2+) chromophore and methyl viologen as a co-oxidant. These reactions enable the cycloaddition of substrates whose thermal Die Is-Alder cycloadditions are electronically mismatched and thus require forcing conditions. Nevertheless, the radical cation cycloadditions can be conducted on gram scale using ambient sunlight as the only source of irradiation. (C) 2012 Elsevier Ltd. All rights reserved.