Thioamide directed Co(III) catalyzed selective amidation of C(sp3)-H bonds

A mild, oxidant-free and selective Cp*CoIII-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*CoIII catalyzed conditions. The observed regioselectivity towards primary C(sp3)-H activation is supported by computational studies and the cyclometalation is proposed to proceed via 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/quinolone classes for Cp*CoIII catalyzed C(sp3)-H functionalization and the first to exploit thioamides