No 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 )Á3H 2 O, 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.

Some reactivity in the oxidation of methanol to formaldehyde has been spectroscopically detected on the methanolic mother liquors of a copper(ii) complex of a Schiff base ligand derived from the condensation of 8-hydroxyquinoline-2-carboxaldehyde and 2-tosylaminomethylaniline. An investigation has shown that 2-tosylaminomethylaniline (HA(TS)) plays a dual role in the oxidative process acting as a N-donor ligand and reacting in situ with formaldehyde, which leads to 3-tosyl-1,2,3,4-tetrahydroquinazoline (1). This was characterized by using both spectroscopic and X-ray diffraction techniques. The influence of 8-hydroxyquinoline derivatives, water and ligand stoichiometry on the yield of 1 was studied.

The degradation under ambient humidity and room temperature of Pd(OAc)2(NEt3), which is an efficient catalyst for the aerobic oxidation of alcohols, to diethylamine and acetaldehyde derivatives is disclosed.