B(C6F5)3-catalyzed synthesis of coumarins via Pechmann condensation under solvent-free conditions

Tris(pentafluorophenyl)borane [B(C6F5)(3)] catalyzed simple, efficient and environmentally benign protocol has been developed for the Pechmann condensation using variety of phenols and beta-ketoesters under solvent-free conditions to afford coumarin derivatives. The present protocol displayed significant advantages such as low catalyst loading, short reaction time, mild reaction conditions, low toxicity, easy work-up, high yields, and compatibility with other functional groups. In addition, it is a convenient, clean, and fast alternative approach for synthesizing variety of coumarin derivatives. Moreover, the applicability of this method towards large-scale synthesis demonstrated its suitability for the industrial application. [GRAPHICS] .