<i>rac</i>-(9<i>R</i>,10<i>R</i>)-3,6,9,10-Tetrabromo-8,8-dimethyl-9,10-dihydro-2<i>H</i>,8<i>H</i>-pyrano[2,3-<i>f</i>]chromen-2-one (tetrabromoseselin): a photobiochemically active pyranocoumarin

The title molecule, C 14 H 10 Br 4 O 3 , is a tetrabrominated substituted pyranocoumarin synthesized by bromination of seselin (systematic name: 8,8-dimethyl-2 H ,8 H -pyrano[2,3- f ]chromene-2-one) isolated from the Indian herb Trachyspermum stictocapum . The pyran ring has a distorted half-chair conformation and its mean plane is inclined to mean plane of the coumarin unit by 3.33 (17)°. In the crystal, molecules are linked by pairs of C—H...O hydrogen bonds, forming inversion dimmers with an R 2 2 (16) ring motif. The dimers are linked by pairs of C—H...Br hydrogen bonds, enclosing an R 2 2 (16) ring motif, forming chains propagating along the [1-10] direction. Within the chains there are offset π–π interactions involving…