Photoredox-Catalyzed Dehydrogenative Csp<sup>3</sup>–Csp<sup>2</sup> Cross-Coupling of Alkylarenes to Aldehydes in Flow
Oliver Griffiths, Henrique A. Esteves, Yiding Chen, Karin Sowa, Oliver May, Peter Morse, David C. Blakemore, Steven V. Ley
Abstract
Executing photoredox reactions in flow offers solutions to frequently encountered issues regarding reproducibility, reaction time, and scale-up. Here, we report the transfer of a photoredox-catalyzed benzylic coupling of alkylarenes to aldehydes to a flow chemistry setting leading to improvements in terms of higher concentration, shorter residence times, better yields, ease of catalyst preparation, and enhanced substrate scope. Its applicability has been demonstrated by a multi-gram-scale reaction using high-power light-emitting diodes (LEDs), late-stage functionalization of selected active pharmaceutical ingredients (APIs), and also a photocatalyst recycling method.