Novel One-Pot Three- and Pseudo-Five-Component Reactions: Synthesis of Functionalized Benzo[g]- and Dihydropyrano[2,3-g]chromene Derivatives

A novel and efficient method has been developed for the synthesis of highly functionalized benzo[g]- and dihydropyrano[2,3-g]chromene derivatives via addition and subsequently cyclization of 2-hydroxynaphthalene-1,4-dione or 2,5-dihydroxycyclohexa-2,5-diene-1,4-dione to the condensation product of an aldehyde with malononitrile in the presence of a catalytic amount of Et3N in CH3CN at ambient temperature. The procedures are very facile. The products can be obtained with simple filtration in high yields, and no more purification is needed. These compounds are closely related to ring systems such as beta-lapachone, alpha-xiloidone, lambertellin, pyranokunthone B, and WS-5995A, which have a broad spectrum of biological activities.