Visible light activation of Boronic Esters enables efficient photoredox C(sp2)–C(sp3) cross-couplings in flow

Fabio Lima^a, Dr. Mikhail A. Kabeshov^a, Dr. Duc N. Tran^a, Dr. Claudio Battilocchio^a, Dr. Joerg Sedelmeier^b, Dr. Gottfried Sedelmeier^b, Dr. Berthold Schenkel^b, S. V. Ley^*a

• ^* Corresponding author
• ^a Department of Chemistry, University of Cambridge, Cambridge, UK
• ^b Novartis Pharma AG, Basel, Switzerland

We report herein a new method for the photoredox activation of boronic esters. Using these reagents, an efficient and high-throughput continuous flow process was developed to perform a dual iridium- and nickel-catalyzed C(sp2)–C(sp3) coupling by circumventing solubility issues associated with potassium trifluoroborate salts. Formation of an adduct with a pyridine-derived Lewis base was found to be essential for the photoredox activation of the boronic esters. Based on these results we were able to develop a further simplified visible light mediated C(sp2)–C(sp3) coupling method using boronic esters and cyano heteroarenes under flow conditions.

Read the publication that featured this abstract