title: Visible Light Activation of Boronic Esters Enables Efficient Photoredox C(sp2)-C(sp3) Cross-Couplings in Flow.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
authors.forename: Fabio
authors.identifier: 0000-0003-2127-9568
authors.initials: F
authors.lastname: Lima
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Kabeshov
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
authors.forename: Duc N
authors.initials: DN
authors.lastname: Tran
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK.
authors.forename: Claudio
authors.identifier: 0000-0002-4601-8527
authors.initials: C
authors.lastname: Battilocchio
authors.affiliation: Novartis Pharma AG, Novartis Campus, 4002, Basel, Switzerland.
authors.forename: Joerg
authors.initials: J
authors.lastname: Sedelmeier
authors.affiliation: Novartis Pharma AG, Novartis Campus, 4002, Basel, Switzerland.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Sedelmeier
authors.affiliation: Novartis Pharma AG, Novartis Campus, 4002, Basel, Switzerland.
authors.forename: Berthold
authors.initials: B
authors.lastname: Schenkel
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK. svl1000@cam.ac.uk.
authors.forename: Steven V
authors.identifier: 0000-0002-7816-0042
authors.initials: SV
authors.lastname: Ley
keywords: boronic esters; cross-coupling; flow chemistry; photoredox catalysis; synthetic methods