Palladium-Catalyzed Cross Coupling of Benzylammonium Salts with Boronic Acids under Mild Conditions
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Peer-reviewed
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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
1437-210X
Volume Title
49
Publisher
Georg Thieme Verlag
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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)
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.