Ru-Catalyzed Deoxygenative Functionalization of Phenols via π-Coordination Activation: Mechanochemical Access to N-Aryl Amides and α-Aryl Carbonyls.

Given the vast occurrence and availability of both primary amides and phenols, the synthesis of N-aryl amides via direct coupling between these starting materials would be much attractive. Herein, we report an efficient method for the mechanochemical synthesis of N-aryl amides via ruthenium-catalyzed direct amidation of unprotected phenols with primary amides with water as the sole byproduct. Unexpectedly, replacing amides with methyl carboxylic acids, esters, or ketones, the same reaction led to the formation of α-aryl carbonyl derivatives instead of the anticipated aryl carboxylates. The synthetic strategy accepts a wide scope of primary amides, alkyl carbonyls, and phenolic substrates to deliver 28 expected N-aryl amides and 14 unexpected α-aryl carbonyl derivatives with good to excellent yields. The developed synthetic approach would serve as the better alternative to the classical cross-coupling reactions in context to the PASE (pot, atom, and step economy) synthesis and late-stage modification of structurally complex molecules, including natural products and pharmaceuticals.