Computational Study on the Fate of Oxidative Directing Groups in Ru(II), Rh(III), and Pd(II) Catalyzed C–H Functionalization

• Published in: Journal of organic chemistry Vol. 85; no. 19; pp. 12594 - 12602
• Main Authors: Liu, Siqi, Pu, Maoping, Wu, Yun-Dong, Zhang, Xinhao
• Format: Journal Article
• Language: English
• Published: American Chemical Society 02.10.2020
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.0c01775

Activation of C–H bonds assisted by a directing group is indispensable in organic synthesis. Among them, utilizing oxidative directing groups that can serve as an internal oxidant to drive the M n /M n+2 catalytic cycle has recently become a promising strategy. A survey of published reactions involving N-alkoxyamides or N-acyloxyamides reveals that not all N–O bonds act as an internal oxidant. We have therefore systematically investigated the effect of the oxidative groups on a model reaction catalyzed by Ru­(II), Rh­(III), and Pd­(II) complexes. DFT calculations show that N-methoxy and N-acyloxy groups oxidize Ru­(II) to Ru­(IV) and Rh­(III) to Rh­(V), but cannot oxidize a cyclo-Pd­(II) intermediate to Pd­(IV). The stability of the metal imido intermediate 7-M (M = Ru, Rh, and Pd) controls whether the oxidation occurs or not. N-Acyloxy groups show a more pronounced selectivity than N-methoxy to oxidize Ru­(II) and Rh­(III) species, while no distinctive effect is observed for Pd­(II).