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Author Notes:

Cherry L. Emerson Center for Scientific Computation , Emory University , 1515 Dickey Drive , Atlanta , Georgia 30322 , USA . Email: dmusaev@emory.edu.

We would like to thank CCHF members, including Jin-Quan Yu and Huw M. L. Davies, for many helpful discussions.

We would also like to thank Alexander Rago for synthesizing 5a and 9, Alan M. Swartz for assistance acquiring mass spectra, and Zekai Lin for a preliminary solution to the structure of 15.

Subject:

Research Funding:

This work was supported by the NSF under the CCI Center for Selective C–H Functionalization (CCHF, CHE-1205646) and by The University of Chicago Louis Block Fund for Basic Research and Advanced Study.

JJG was supported by an NSF predoctoral fellowship (DGE-1144082) and by the University of Chicago Department of Chemistry.

The authors gratefully acknowledge NSF MRI-R2 grant (CHE-0958205) and the use of the resources of the Cherry Emerson Center for Scientific Computation.

Use of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06-CH11357.

ChemMatCARS Sector 15 is principally supported by the Divisions of Chemistry (CHE) and Materials Research (DMR), National Science Foundation, under grant number NSF/CHE-1346572.

Mono-N-protected amino acid ligands stabilize dimeric palladium(ii) complexes of importance to C–H functionalization

Journal Title:

Chemical Science

Volume:

Volume 8, Number 8

Publisher:

, Pages 5746-5756

Type of Work:

Article | Final Publisher PDF

Abstract:

Mono-protected amino acid (MPAA) ligands are used in a number of Pd-catalyzed C-H functionalization reactions. MPAAs have been proposed to bind to Pd(ii) via κ 2 -(N,O) coordination, but such binding has not yet been experimentally validated. Herein, we report the synthesis and detailed characterization of a series of MPAA complexes prepared via cyclopalladation of dimethylbenzylamine in the presence of MPAAs. The isolated complexes exist as μ-carboxylato (MPAA) bridged dimers and feature potential M-M cooperativity and secondary sphere hydrogen bonding. Selective MPAA coordination and relay of stereochemistry, previously suggested to uniquely result from κ 2 -(N,O) MPAA coordination, are both observed. The isolated MPAA complexes undergo C-C and C-X (X = Cl, Br, I) bond formation when treated with electrophiles used for catalytic C-H functionalization. Stoichiometric iodination of MPAA palladacycles was found to proceed via a dinuclear palladium species with one equivalent of iodine in the rate limiting transition structure, and the isolated complexes also served as viable precatalysts for catalytic C-H functionalization. Together, these results provide a number of insights into the reactivity of Pd-MPAA complexes relevant to C-H bond functionalization.

Copyright information:

© 2017 The Royal Society of Chemistry.

This is an Open Access work distributed under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License (http://creativecommons.org/licenses/by-nc/3.0/).

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