A mixed crystal of imperatorin and phellopterin, with C--H...O, C--H...pi and pi-pi interactions.

The crystal structure of 9-(3-methylbut-2-enyloxy)-7H-furo[3,2-g]chromen-7-one-4-methoxy-9-(3-methylbut-2-enyloxy)-7H-furo[3,2-g]chromen-7-one (0.926/0.074), 0.926C(16)H(14)O(4)*- x 0.074C(17)H(16)O(5), is characterized by two independent imperatorin molecules in the asymmetric unit, which exhibit different side-chain conformations. A small amount of phellopterin overlaps with one of the two imperatorin molecules. The supramolecular structure is supported by C--H...O, C--H...pi and pi-pi interactions.