Crystal and molecular structure of a root inhibitor fromEucalyptus grandis, 4-ethyl-1-hydroxy-4,8,8,10,10-pentamethyl-7,9-dioxo-2,3-dioxabicyclo [4.4.0]decene-5

Abstract

The crystal structure of C15H22O5, a root inhibitor isolated from adult leaves ofEucalyptus grandis, has been determined by direct methods with Cukα diffractometer data and refined by full-matrix least-squares calculations toR = 0·046 for 1829 statistically significant reflexions. The compound, a racemate, crystallizes in the monoclinic space groupP21/c, with unit cell dimensionsa = 11·767,b = 12·063,c = 10·906 A, β = 103·2° andZ = 4. The molecular skeleton consists of a 2,3-dioxabicyclo[4.4.0]decene system with one hydroxyl, two carbonyl, one ethyl and five methyl side groups. The dihedral angle at the peroxide bond is 76·8° and the O-O bond distance is 1·480 A. The molecules are linked in the c direction by hydrogen bonds between the hydroxyl group and one of the carbonyl oxygen atoms.