Improved Ligand for Cross-Couplings at Low Pd Loadings

  • Author:
  • Published: 16 May 2020
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
  • Source / Publisher: Chemical Science/Royal Society of Chemistry
  • Associated Societies: Royal Society of Chemistry (RSC), UK
thumbnail image: Improved Ligand for Cross-Couplings at Low Pd Loadings

Suzuki–Miyaura cross-coupling reactions are commonly used to create C–C bonds. They are catalyzed by palladium, which is rare and expensive. Researchers have tried to use alternative, cheap, earth-abundant metals for this type of reaction, with some success at high catalyst concentrations. However, for the production of, e.g., pharmaceuticals, residual metals have to be removed after the reaction—and the high catalyst loadings required for these processes make this difficult. Catalysts that work even at very low loadings, would, thus, be useful.

Donald H. Aue, Bruce H. Lipshutz, University of California Santa Barbara, USA, and colleagues have developed a new ligand, N2Phos (pictured), that can be used in Suzuki–Miyaura couplings with low palladium loadings (0.10–0.25 mol%). The ligand combines a biaryl skeleton with a phosphine unit and two bulky substituted amino groups. The team synthesized the ligand starting from 2,7-dibromonaphthalene, which was subjected to a double amination and a subsequent bromination. A cross-coupling reaction was then used to create the biaryl unit. Finally, a lithiation followed by a phosphine insertion gave the desired product.

The researchers used the new ligand together with Pd(OAc)2 to catalyze Suzuki–Miyaura cross-couplings between chloro-, bromo-, or iodoaryls and aryl boronic acids. They found that the developed ligand system gave good yields of the biaryl products at low catalyst loadings. The catalyst can also be used in water, which allows for environmentally friendly transformations.



Article Views: 572

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

Bookmark and Share

If you would like to reuse any content, in print or online, from, please contact us first for permission. more

CONNECT: on Facebook on Twitter on YouTube on LinkedIn Sign up for our free newsletter

Magazine of Chemistry Europe (16 European Chemical Societies)published by Wiley-VCH