Cr-mediated photocatalytic decarboxylative coupling of alpha-oxo acids with benzylic pyridinium salts

Herein, we report the chromium/photoredox dual catalytic synthesis of ketones using alpha-oxo acids with benzylic pyridinium salts. This reaction proceeded by photocatalytic generation of an acyl radical from alpha-oxo acids and a benzylic radical from pyridinium salts, followed by chromium-catalyzed cross-coupling of the generated acyl radical with benzylic radical. Control experiments and DFT calculations supported our suggested mechanism of the radical reaction. This protocol features good tolerance of functional groups, broad scope of substrates and mild reaction conditions. This transformation was easy to scale-up efficiently. Our methodology could be employed for building complexity in organic synthesis. We developed a method for chromium/photoredox dual catalytic synthesis of ketones using alpha-oxo acids with benzylic pyridinium salts.