organic compounds
The title structure, 15,18-dimethyl-5-dioxo-14-oxapentacyclo[11.4.1.02,15.04,13.06,11]octadeca-3,6,8,10-tetraene-18-carbaldehyde, C20H18O4, is a novel naphthoquinone, isolated from Stereospermum personatum. In the bicyclic system, all three six-membered rings adopt a boat conformation. Two intermolecular C=OH—C interactions link the molecules into a chain.
organic compounds
The title compound, 1-[2-hydroxy-4-methoxy-5-(3-methylbut-2-enyl)phenyl]-3-(4-hydroxyphenyl)prop-2-en-1-one (also known as bavachalcone), C21H22O4, is a polymorphic form of a previously reported structure [Bhalla et al. (1968). Tetrahedron Lett. 20, 2401–2406]. The molecules in both polymorphs exhibit nearly identical conformations. In each polymorph, strong intra- and intermolecular hydrogen-bonded chains, involving the hydroxyl groups, are formed. A weak C—HO interaction is seen in the present structure, but was not observed in the previously reported polymorph.