Visible light mediated photoredox reactions catalyzed by recyclable PIB-bound ruthenium photoredox catalysts

This report describes the preparation of a PIB-bound Ru(II)-bipyridine complex [Ru(PIB-bpy)(3)Cl-2], and its use as a recyclable photoredox catalyst to carry out both oxidative C-C bond cleavage of aldehydes and [2 + 2] cycloaddition of bis(enone)s. While this polymer-supported Ru catalyst could be successfully recovered and reused for 5 cycles with no loss of catalytic activity and with leaching levels of ca. 1% of the charged catalyst for these reactions, other reactions like photodimerization or alkyl halide synthesis that require a more polar solvent medium for successful reactions of the low molecular weight catalyst proceeded either with varying selectivity or in low yield because of solubility limitations of the PIB-supported catalyst in the more polar solvents that are often used for this chemistry.