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Fe Coupling in CPME


Iron-Catalyzed Cross-Coupling of Unactivated Secondary Alkyl Thio Ethers and Sulfones with Aryl Grignard Reagents

Department of Chemistry, University of Illinois, 245 Roger Adams Laboratory, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
J. Org. Chem., 2013, 78 (24), pp 12593–12628
DOI: 10.1021/jo402246h
Publication Date (Web): November 20, 2013
Copyright © 2013 American Chemical Society
*Tel: (217) 333-0066. Fax: (217) 333-3984. E-mail: sdenmark@illinois.edu.

Abstract

Abstract Image
The first systematic investigation of unactivated aliphatic sulfur compounds as electrophiles in transition-metal-catalyzed cross-coupling are described. Initial studies focused on discerning the structural and electronic features of the organosulfur substrate that enable the challenging oxidative addition to the C(sp3)–S bond. Through extensive optimization efforts, an Fe(acac)3-catalyzed cross-coupling of unactivated alkyl aryl thio ethers with aryl Grignard reagents was realized in which a nitrogen “directing group” on the S-aryl moiety of the thio ether served a critical role in facilitating the oxidative addition step. In addition, alkyl phenyl sulfones were found to be effective electrophiles in the Fe(acac)3-catalyzed cross-coupling with aryl Grignard reagents. For the latter class of electrophile, a thorough assessment of the various reaction parameters revealed a dramatic enhancement in reaction efficiency with an excess of TMEDA (8.0 equiv). The optimized reaction protocol was used to evaluate the scope of the method with respect to both the organomagnesium nucleophile and sulfone electrophile.
Optimization studies, calibration tables, and 1H and 13C NMR spectra. This material is available free of charge via the Internet at http://pubs.acs.org.


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Article Views: 3,993 Times
Received 9 October 2013
Published online 20 November 2013
Published in print 20 December 2013
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