title: Iterative reactions of transient boronic acids enable sequential C-C bond formation.
abstract: The ability to form multiple carbon-carbon bonds in a controlled sequence and thus rapidly build molecular complexity in an iterative fashion is an important goal in modern chemical synthesis. In recent times, transition-metal-catalysed coupling reactions have dominated in the development of C-C bond forming processes. A desire to reduce the reliance on precious metals and a need to obtain products with very low levels of metal impurities has brought a renewed focus on metal-free coupling processes. Here, we report the in situ preparation of reactive allylic and benzylic boronic acids, obtained by reacting flow-generated diazo compounds with boronic acids, and their application in controlled iterative C-C bond forming reactions is described. Thus far we have shown the formation of up to three C-C bonds in a sequence including the final trapping of a reactive boronic acid species with an aldehyde to generate a range of new chemical structures.
authors.affiliation: Department of Chemistry, Innovative Technology Centre, University of Cambridge, Lensfield Road, Cambridge CB2 1EW.
authors.forename: Claudio
authors.identifier: http://orcid.org/0000-0002-4601-8527
authors.initials: C
authors.lastname: Battilocchio
authors.affiliation: Department of Chemistry, Innovative Technology Centre, University of Cambridge, Lensfield Road, Cambridge CB2 1EW.
authors.forename: Florian
authors.initials: F
authors.lastname: Feist
authors.affiliation: Department of Chemistry, Innovative Technology Centre, University of Cambridge, Lensfield Road, Cambridge CB2 1EW.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hafner
authors.affiliation: Department of Chemistry, Innovative Technology Centre, University of Cambridge, Lensfield Road, Cambridge CB2 1EW.
authors.forename: Meike
authors.initials: M
authors.lastname: Simon
authors.affiliation: Department of Chemistry, Innovative Technology Centre, University of Cambridge, Lensfield Road, Cambridge CB2 1EW.
authors.forename: Duc N
authors.initials: DN
authors.lastname: Tran
authors.affiliation: Department of Chemistry, Innovative Technology Centre, University of Cambridge, Lensfield Road, Cambridge CB2 1EW.
authors.forename: Daniel M
authors.identifier: http://orcid.org/0000-0002-3735-3198
authors.initials: DM
authors.lastname: Allwood
authors.affiliation: Pfizer Worldwide Medicinal Chemistry, The Portway Building, Granta Park, Cambridge CB21 6GS, UK.
authors.forename: David C
authors.initials: DC
authors.lastname: Blakemore
authors.affiliation: Department of Chemistry, Innovative Technology Centre, University of Cambridge, Lensfield Road, Cambridge CB2 1EW.
authors.forename: Steven V
authors.initials: SV
authors.lastname: Ley