Thioamide-Directed Cobalt(III)-Catalyzed Selective Amidation of C(sp3 )-H Bonds

Peng Wen Tan; Adrian M Mak; Michael B Sullivan; Darren J Dixon; Jayasree Seayad

doi:10.1002/anie.201709273

Thioamide-Directed Cobalt(III)-Catalyzed Selective Amidation of C(sp³ )-H Bonds

Angew Chem Int Ed Engl. 2017 Dec 22;56(52):16550-16554. doi: 10.1002/anie.201709273. Epub 2017 Nov 30.

Authors

Peng Wen Tan¹, Adrian M Mak², Michael B Sullivan², Darren J Dixon³, Jayasree Seayad¹

Affiliations

¹ Organic Chemistry, Institute of Chemical and Engineering Sciences, 8 Biomedical Grove, Neuros, #07-01, Singapore, 138665, Singapore.
² Institute of High Performance Computing, 1 Fusionopolis Way #16-16, Singapore, 138632, Singapore.
³ Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, UK.

PMID: 29080308
DOI: 10.1002/anie.201709273

Abstract

A mild, oxidant-free, and selective Cp*Co^III -catalyzed amidation of thioamides with robust dioxazolone amidating agents via C(sp³ )-H bond activation to generate the desired amidated products is reported. The method is efficient and allows for the C-H amidation of a wide range of functionalized thioamides with aryl-, heteroaryl-, and alkyl-substituted dioxazolones under the Cp*Co^III -catalyzed conditions. The observed regioselectivity towards primary C(sp³ )-H activation is supported by computational studies and the cyclometalation is proposed to proceed by means of an external carboxylate-assisted concerted metalation/deprotonation mechanism. The reported method is a rare example of the use of a directing group other than the commonly used pyridine and quinolone classes for Cp*Co^III -catalyzed C(sp³ )-H functionalization and the first to exploit thioamides.

Keywords: C−H activation; amidation; cobalt; selectivity; thioamides.

Publication types

Research Support, Non-U.S. Gov't