Published as part of the Bürgenstock Special Section 2017 Future Stars in Organic Chemistry
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.
Key words
cross-coupling - ammonium salts - palladium catalysis - diarylmethanes - fluorenes
