Replacing a stoichiometric silver oxidant with air: ligated Pd(II)-catalysis to β-aryl carbonyl derivatives with improved chemoselectivity

Air was employed as a green reoxidant of Pd(0), replacing stoichiometric and toxic silver salt, in the chelation-controlled Pd(II)-modulated arylative enolization of prop-2-en-1-ols to acquire synthetically-important beta-aryl carbonyl derivatives. This green approach, which didn't require acid or base, allowed the compatibility of a range of functionalities (inclusive of -I, -Br & -Cl), resulting in the construction of structurally-diverse dihydrochalcones, alpha-benzyl-alpha'-alkyl acetones, a-benzyl beta-keto esters and dihydrocinnamaldehydes. In addition to organoboronic acids, efficient coupling was also achieved with boronic esters and trifluoroborate salts. A deuterium labelling experiment revealed an interesting 1,2-hydrogen shift after beta-arylation in the catalytic process.