Nepetanudone, a dimer of the alpha-pyrone 5,9-dehydronepetalactone

The title compound C20H24O4 crystallizes in the orthorhombic space group P2(1)2(1)2, with a = 10,245(3), b = 17.103(3), c = 9.879(3) Angstrom, D-c = 1.260 g cm(-3), and Z = 4. Nepetanudone is postulated to be formed by a [4 + 4] cycloaddition of two 5,9-dehydronepetalactone moieties to give an asymmetric dimer in which each pair of atoms is magnetically nonequivalent. The compound was recovered from extracts of Nepeta nuda ssp. albiflora.