Near UV irradiation of aerated solutions of (Et 4N) 2[CuCl 4] in dichloromethane causes the decomposition of CH 2Cl 2, as evidenced by the buildup of HCl, C 2H 2Cl 4, and peroxides. A net reduction to [CuCl 2] (-) occurs in the early stages, but is later reversed. In CH 2Cl 2, [CuCl 4] (2-) is in equilibrium with [Cu 2Cl 6] (2-), and only the latter species is photoactive. The decomposition is initiated by the photodissociation of chlorine atoms, which propagate to peroxy radicals, CHCl 2OO. Experimental evidence, including a linear dependence of the decomposition rate on the incident light intensity and on the fraction of light absorbed by [Cu 2Cl 6] (2-), is consistent with a mechanism in which CHCl 2OO is reduced by electron transfer from [CuCl 2] (-), following which protonation yields CHCl 2OOH. The hydroperoxide accumulates during irradiation and it too can reoxidize [CuCl 2] (-). The quantum yield for HCl production at the outset of irradiation at 313 nm is 1.3 mol/einstein, based on the fraction of light absorbed by [Cu 2Cl 6] (2-).

The formation of homocoupled alkane byproducts have been identified in the reduction of bromoalkanes via photoredox gold catalysis with dimeric Au(I) complexes. This prompted further investigation into the mechanism of formation of these byproducts and the diversity of C-X bonds amenable to this transformation. Examples were found when considering bromoalkanes while a wide variety of iodoarenes underwent this process in good to excellent yields. The light enabled homocoupling of iodoarenes made possible by photoredox gold catalysis is reported.

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The formal synthesis of (�)-salvinorin A is presented. Our approach utilizes two distinct gold(I) catalytic processes. The combination of a gold(I)-catalyzed reaction with an intermolec-ular Diels-Alder reaction followed by a gold(I)-catalyzed photoredox reaction generated in eight steps the framework of the natural product with high diastereoselectivity.