Organocatalytic, rapid and facile cyclotrimerization of isocyanates using tetrabutylammonium phthalimide-N-oxyl and tetraethylammonium 2-(carbamoyl) benzoate under solvent-free conditions

摘要

Tetrabutylammonium phthalimide-N-oxyl and tetraethylammonium 2-(carbamoyl)benzoate were found to be effective and easily accessible organocatalysts for selective cylotrimerization of aryl and alkyl isocyanates under mild reaction conditions. The reaction proceeds smoothly using very low catalyst loadings of these metal-free organocatalysts (0.025 and 0.25 mol%, respectively) under solvent-free conditions at room temperature within a very short reaction time.