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

Abstract

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 β-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, α-benzyl-α′-alkyl acetones, α-benzyl β-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 β-arylation in the catalytic process.