Carbonylative Hydroacylation of Styrenes with Alkyl Halides by Multiphoton Tandem Photoredox Catalysis in Flow

Abstract

The abundance, structural diversity, and versatility of ketones give prominence to this carbonyl functional group in synthetic chemistry. The assembly of ketones via the carbonylative hydroacylation of alkenes represents a powerful modular strategy for the synthesis of unsymmetric ketone products. Here, we report the photocatalytic carbonylative hydroacylation of styrenes with unactivated alkyl halides. This protocol unifies the visible-light multiphoton catalytic cycle of [Ir(ppy)2(dtb-bpy)]+ with flow chemistry to engage energy-demanding alkyl bromides and iodides at moderate pressures of carbon monoxide. The mild and practical methodology was employed to prepare a diverse array of 44 unsymmetric dialkyl ketones from primary, secondary, and tertiary unactivated alkyl halides. We demonstrate the application of flow chemistry technology to achieve spatially resolved chemoselectivity and broad functional group tolerance for the mild generation of functionalized C(sp3)-rich ketone products.