Green Synthesis of Spiropyranone 3-Aryl-4-Methylcoumarin Derivatives using Carbonyldiimidazole

Abstract

A series of spiropyranone 3-aryl-4-methylcoumarin derivatives have been synthesized from monospiro-2-hydroxy acetophenone in a novel and efficient green method using imidazolyl intermediates and inorganic base. Imidazolyl intermediates were in turn generated by grinding the respective phenylacetic acid along with carbonyldiimidazole (CDI). Similarly, monospiro-2-hydroxy acetophenone derivatives were prepared selectively by avoiding formation of bis derivatives following literature procedure. The titled compounds were purified by preparative TLC technique and were characterized by IR, 1H NMR, 13C NMR as well as mass spectral methods