Issue 24, 2022

Merging dual photoredox/cobalt catalysis and boronic acid (derivatives) activation for the Minisci reaction

Abstract

The merger of photoredox catalysis and organometallic chemistry has effectively enabled multiple cross-coupling pathways. Here we report a visible-light promoted photoredox-cobalt catalyzed Minisci reaction of N-heteroarenes under mild conditions, employing various boronic acids and derivatives as alkyl radical precursors. This study demonstrates the prominent ability of the Co co-catalyst to promote the oxidation step of the photocatalytic cycle following a reductive quenching pathway, thus avoiding the use of stoichiometric (inorganic) oxidants. This feature enables the straightforward application of photo-flow conditions, particularly attractive for an easy scale-up and to enhance the efficiency of the reaction (throughput: 0.78 mmol·h−1 in flow vs. 0.02 mmol·h−1 in batch). Furthermore, the process is predominantly selective towards the C2-alkylation of quinolines and a mechanistic rationale has been provided with both experimental and DFT calculation support. The developed protocol demonstrates broad applicability for the alkylation of different N-heteroarenes under suitable homogeneous conditions for a flow-compatible Minisci reaction.

Graphical abstract: Merging dual photoredox/cobalt catalysis and boronic acid (derivatives) activation for the Minisci reaction

Supplementary files

Article information

Article type
Research Article
Submitted
13 sen 2022
Accepted
08 noy 2022
First published
10 noy 2022

Org. Chem. Front., 2022,9, 6958-6967

Merging dual photoredox/cobalt catalysis and boronic acid (derivatives) activation for the Minisci reaction

S. Pillitteri, P. Ranjan, G. M. Ojeda-Carralero, L. Y. Vázquez Amaya, J. E. Alfonso-Ramos, E. V. Van der Eycken and U. K. Sharma, Org. Chem. Front., 2022, 9, 6958 DOI: 10.1039/D2QO01441F

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