Serendipitous formation of 3-tosyl-1,2,3,4-tetrahydroquinazoline

Abstract

Both experimental and computational studies were undertaken to elucidate the formation process of 3-tosyl-1,2,3,4-tetrahydroquinazoline from methanolic mother liquors of Pd(L_BS)·3H₂O, where L_BS is the dianionic form of the imine ligand N-{2-[(8-hydroxyquinolin-2-yl)methyleneamino]benzyl}-4-methylbenzenesulfonamide. Experimental studies have shown that the tetrahydroquinazoline is obtained by condensation of 2-tosylaminomethylaniline and formaldehyde, which come from the acid-catalyzed hydrolysis of the imine ligand L_BS and metal-mediated aerobic oxidation of methanol, respectively. Computational studies have revealed relevant intermediates and key steps in the reaction pathway.