Self-catalyzed direct amidation of ketones: A sustainable procedure for acetaminophen synthesis

• A procedure for fast, high yielding, one-pot aromatic amide synthesis
• Hydroxylamine hydrochloride as oximation agent and rearrangement catalyst
• High yield of acetaminophen is obtained at 110 °C in solventless condition.

High yielding amination of ketones and benzaldehyde in acid-less conditions has been conducted on several ketones to achieve amides and nitriles. The reactivity of the selected substrates showed to depend on both oximation and Beckmann rearrangement reaction rates. Oximation allows the in-situ production of hydrochloric acid that enables Beckmann rearrangement of the oxime to form the corresponding amide or nitrile. It is noteworthy that, using this one-pot synthetic approach, N-acetyl-4-aminophenol (acetaminophen drug), can be easily synthesized starting from 4-hydroxy-acetophenone in high yield. Acetanilide and ε-caprolactam can be also efficiently synthesized employing this synthetic procedure.

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