Net-1,2-Hydrogen Atom Transfer of Amidyl Radicals: Toward the Synthesis of 1,2-Diamine Derivatives

By:Yonggang Jiang, Dongxiang Liu, Madeline E. Rotella, Guogang Deng, Zhengfen Liu, Wen Chen, Hongbin Zhang, Marisa C. Kozlowski, Patrick J. Walsh, and Xiaodong Yang

Journal of the American Chemical Society

DOI：https://doi.org/10.1021/jacs.3c04376

Published：2023-July-13

Abstract

Hydrogenatom transfer (HAT) processes are among themost usefulapproaches for the selective construction of C(sp(3))-C(sp(3)) bonds. 1,5-HAT with heteroatom-centered radicals (O-& BULL;, N-& BULL;) have been well establishedand are favored relative to other 1,n-HAT processes.In comparison, net 1,2-HAT processes have been observed infrequently.Herein, the first amidyl radicalls are reported that preferentiallyundergo a net 1,2-HAT over 1,5-HAT. Beginning with single electrontransfer from 2-azaallyl anions to N-alkyl N-aryloxy amides, the latter generate amidyl radicals. Theamidyl radical undergoes a net-1,2-HAT to generate a C-centered radicalthat participates in an intermolecular radical-radical couplingwith the 2-azaallyl radical to generate 1,2-diamine derivatives. Mechanisticand EPR experiments point to radical intermediates. Density functionaltheory calculations provide support for a base-assisted, stepwise-1,2-HATprocess. It is proposed that the generation of amidyl radicals underbasic conditions can be greatly expanded to access & alpha;-amino C-centeredradicals that will serve as valuable synthetic intermediates.