V. Pattabhi et al., CYCLOADDITION PRODUCTS OF CLO-[6.2.1.0(2,7)]UNDECA-2(7),4,9-TRIENE-3,6-DIONE, Acta crystallographica. Section C, Crystal structure communications, 50, 1994, pp. 594-597
The crystal structures of 8)]henicosa-4(9),-6,13(18),15-tetraene-3,10-
dione, C21H18O2(I), and exo,syn,syn-hexacyclo[10.4.2. 13,16)]nona-deca
-4(9),6,14,17-tetraene-3,10-dione, C19H16O2 (11), are reported. The pa
cking of the molecules in both structures is stabilized by van der Waa
l's forces.