An efficient route to coumarin derivatives under dual catalysis, an organo- and a Lewis acid catalyst

Direct Synthesis of Coumarin Derivatives from Alkynoic Esters via Dual-organocatalysis

An efficient synthetic method for coumarin derivatives was developed using a dual-organocatalytic reaction. A combination of p-toluenesulfonic acid monohydrate and piperidine was found to efficiently catalyze the cyclization between salicylaldehydes and alkynoic esters to give various coumarin derivatives in good yield and high selectivity. Mechanistic and kinetic data suggested that the conjugate addition between piperidine and alkynoic esters played a crucial role in the reaction mechanism.

Ultrasound mediated, green innovation for the synthesis of polysubstituted 1,4-dihydropyridines

An atom efficient protocol via a one-pot four-component cyclocondensation reaction catalyzed by copper(i) iodide in aqueous medium under ultrasonic irradiation has been developed for the synthesis of novel polysubstituted 1,4-dihydropyridines.