6a,14a-cis-6,6a,7,14a-Tetrahydrochromeno[4′,3′:3,4]pyrano[3,2-c]coumarin

Abstract

The title compound, C 19 H 14 O 4 , crystallizes with two molecules in the asymmetric unit. The dihydropyran rings adopt a halfchair conformation or a conformation intermediate between a sofa and half-chair. The inversion-related type A and B molecules and vice versa are linked by CÐHÁ Á ÁO hydrogen bonds, forming an in®nite chain along the a axis. The molecular packing is stabilized by CÐHÁ Á ÁO interactions. Comment Coumarin derivatives can undergo photocycloaddition with themselves (Song et al., 1971). Coumarin dyes are widely used in lasers owing to their tunability (Masilamani et al., 1986; Elnagdi et al., 1997). The coumarin ring system is also present in a number of natural products (Cisowski, 1983, 1984), which are found to possess antimicrobial (Zaha & Hazem, 2002), antioxidant (Wei et al., 1999; Sugioka et al., 1997), anticoagulation (Cole et al., 1988) and antiplatelet (Roma et al., 2003) activities. 4,7-Disubstituted coumarins give rise to interesting crystal structures in terms of their photochemical reactivity (Gnanaguru et al., 1985). The X-ray crystal structure analysis of the title compound, (I), was carried out as part of our studies of coumarin derivatives.