29728-11-8Relevant academic research and scientific papers
Enantioselective C(sp3)–H Amidation of Thioamides Catalyzed by a CobaltIII/Chiral Carboxylic Acid Hybrid System
Fukagawa, Seiya,Kato, Yoshimi,Tanaka, Ryo,Kojima, Masahiro,Yoshino, Tatsuhiko,Matsunaga, Shigeki
, p. 1153 - 1157 (2019)
Recent advances in CpxMIII catalysis (M=Co, Rh, Ir) have enabled a variety of enantioselective C(sp2)?H functionalization reactions, but enantioselective C(sp3)?H functionalization is still largely unexplored. We describe an asymmetric C(sp3)?H amidation of thioamides using an achiral CoIII/chiral carboxylic acid hybrid catalytic system, which provides easy and straightforward access to chiral β-amino thiocarbonyl and β-amino carbonyl building blocks with a quaternary carbon stereocenter.
Thioamide-Directed Cobalt(III)-Catalyzed Selective Amidation of C(sp3)?H Bonds
Tan, Peng Wen,Mak, Adrian M.,Sullivan, Michael B.,Dixon, Darren J.,Seayad, Jayasree
supporting information, p. 16550 - 16554 (2017/12/07)
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 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*CoIII-catalyzed C(sp3)?H functionalization and the first to exploit thioamides.
