Copper-catalyzed remote C(sp3)-H azidation and oxidative trifluoromethylation of benzohydrazides. 2019

Xu Bao, and Qian Wang, and Jieping Zhu
Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH5304, CH-1015, Lausanne, Switzerland.

The Hofmann-Löffler-Freytag (HLF) reaction is a prototypical example of radical-based remote functionalization of unactivated C(sp3)-H bond. While 1,5-hydrogen atom transfer (1,5-HAT) of the amidyl radical is thermodynamically favorable and is well-established, the method for the subsequent functionalization of the translocated carbon radical is still limited. We report herein two catalytic remote C(sp3)-H functionalization protocols. Cu(MeCN)4PF6-catalyzed reaction of 2-alkyl benzohydrazides 3 with TMSN3 in the presence of MeCO2OtBu affords the γ-azido amides 4, while CuCl-catalyzed reaction of 3 with Togni's reagent provides 2-(β-trifluoromethylvinyl)benzamides 5 via an oxidative δ-trifluoromethylation of the alkyl group. Mechanistic studies suggest that the γ-azidation of benzohydrazides 3 goes through 1,5-HAT followed by a Cu-mediated azido transfer cascade, while the oxidative δ-trifluoromethylation of 3 proceeds via, after 1,5-HAT process, a radical-polar crossover mechanism.

UI MeSH Term Description Entries

Related Publications

Xu Bao, and Qian Wang, and Jieping Zhu
February 2019, Angewandte Chemie (International ed. in English),
Xu Bao, and Qian Wang, and Jieping Zhu
January 2012, Journal of the American Chemical Society,
Xu Bao, and Qian Wang, and Jieping Zhu
October 2020, Journal of the American Chemical Society,
Xu Bao, and Qian Wang, and Jieping Zhu
April 2020, Organic letters,
Xu Bao, and Qian Wang, and Jieping Zhu
September 2019, The Journal of organic chemistry,
Xu Bao, and Qian Wang, and Jieping Zhu
June 2010, Organic letters,
Xu Bao, and Qian Wang, and Jieping Zhu
December 2020, Chemical science,
Xu Bao, and Qian Wang, and Jieping Zhu
March 2024, Organic letters,
Xu Bao, and Qian Wang, and Jieping Zhu
May 2020, Organic letters,
Copied contents to your clipboard!