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Palladium-Catalyzed Cross Coupling of Benzylammonium Salts with Boronic Acids under Mild Conditions

Accepted version
Peer-reviewed

Type

Article

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Authors

Turtscher, PL 
Davis, HJ 
Phipps, RJ 

Abstract

Herein, we give a full account of the development of the palladium­-catalysed cross-coupling of benzylammonium salts with boronic acids. A range of benzylamine-derived quaternary ammonium salts can be coupled with boronic acids under relatively mild conditions. Our optimization has identified ligands that can be used to chemoselectively cross-couple at the ammonium in the presence of chlorides. We demonstrate that intramolecular palladium-catalysed C–H activation is also a viable pathway for the putative benzyl-Pd(II) intermediate obtained upon oxidative addition and have optimised this to obtain fluorene in good yield.

Description

Keywords

cross-coupling, ammonium salts, palladium catalysis, di­arylmethanes, fluorenes

Journal Title

Synthesis

Conference Name

Journal ISSN

0039-7881
1437-210X

Volume Title

49

Publisher

Georg Thieme Verlag
Sponsorship
The Royal Society (uf130004)
EPSRC (1502977)
Engineering and Physical Sciences Research Council (EP/K039520/1)
Engineering and Physical Sciences Research Council (EP/N005422/1)
We are grateful to the Engineering and Physical Sciences Research Council (EPSRC, Grant Number EP/N005422/1) and Pfizer for a CASE studentship (H.J.D.), the EPSRC and the Royal Society for a University Research Fellowship (R.J.P.). P.L.T. thanks the Swiss-European Mobility Programme for Traineeships for funding his stay in Cambridge.