One-Pot Catalytic Syntheses of Quinazolinones by Coupling of 2-Aminobenzamide With Primary Alcohols Using a Nickel(II)-ONO Pincer-Like Complex

One-pot syntheses of biologically relevant quinazolinones using acceptorless dehydrogenative coupling (ADC) of 2-aminobenzamide with various alcohols in the presence of a catalytic amount of [NiL(PPh₃)] (1) (H₂L represents N-(2-hydroxy-1-naphthylidene)-N′-(2-thenoyl)hydrazine, where two Hs are the dissociable phenolic and amide protons) are reported. The identity and purity of 1 have been confirmed by infrared and ¹H NMR spectroscopic and X-ray crystallographic studies. A variety of substituted derivatives of quinazolinones have been successfully synthesized using a diverse range of alcohols in 40%–83% yields using 5 mol% of 1. The detailed mechanistic investigation has revealed that the presence of 1 leads to the dehydrogenation of alcohol into aldehyde, followed by the formation of a cyclic aminal via condensation of the aldehyde with 2-aminobenzamide. Ultimately, the dehydrogenation of the aminal provides the desired quinazolinone, producing water and dihydrogen as the by-products, thereby making the present catalytic method environmentally benign and sustainable.