Expedient synthesis of tricyclic benzopyran-2-ones via N-Heterocyclic carbene catalyzed annulation of enals to α-methylene cycloalkanones

Tricyclic benzopyrans are medicinally important biologically active compounds. Synthesis of a series of tricyclic benzopyrans derivatives via N-Heterocyclic carbene (NHC) catalyzed annulation of enals to α-methylidenetetralones/chromanones is described. This reaction afforded the benzopyrans in high yield with aromatic as well as aliphatic enals.