Photoredox-Catalyzed Multicomponent Petasis Reaction in Batch and Continuous Flow with Alkyl Boronic Acids

• Monica Oliva¹
• Prabhat Ranjan¹
• Serena Pillitteri¹
• Guglielmo Attilio Coppola¹
• Monica Messina¹
• Erik V. Van der Eycken^1,2
• Upendra Kumar Sharma¹

• ¹Laboratory for Organic and Microwave-Assisted Chemistry (LOMAC), Department of Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven B-3001, Belgium
• ²Peoples’ Friendship University of Russia (RUDN University), Miklukho-Maklaya street 6, Moscow RU-117198, Russia

Multicomponent reactions (MCRs) are ideal platforms for the generation of a wide variety of organic scaffolds in a convergent and atom-economical manner. Many strategies for the generation of highly substituted and diverse structures have been developed and among these, the Petasis reaction represents a viable reaction manifold for the synthesis of substituted amines via coupling of an amine, an aldehyde and a boronic acid (BA). Despite its synthetic utility, the inherent drawbacks associated with the traditional two-electron Petasis reaction have stimulated continuous research towards more facile and tolerant methodologies. In this regard, we present the use of free alkyl boronic acids as effective radical precursors in this MCR through a single-electron transfer mechanism under mild reaction conditions. We have further demonstrated its applicability to photo-flow reactors, facilitating the reaction scale-up for the rapid assembly of complex molecular structures.

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