Biflora-4,10(19),15-triene: a new diterpene from a termite soldier (Isoptera Termitidae Termitinae)

This communication describes spectrometric, chemical, and x-ray diffraction studies leading to the assignment of the structure to this diterpene. The name assigned is biflora-4,10(19),15-triene on the basis of its skeletal relationship to the violet-red, o-quinonoid antibiotic biflorin, a constituent of the Brazilian medicinal plant Capraria biflora L. The triene was isolated from a hexane extract. The mass spectra and NMR spectra were measured. The compound was esterified with p-bromobenzoyl chloride. The p-bromobenzoate crystallized in the monoclinic crystal system. Lattice parameters were measured. Intensity data were collected on a fully automated four-circle diffractometer. 1666 unique reflections were judged observed after correction for Lorentz, polarization, and background effects. The bromine position was deduced from the Patterson synthesis with complications. Careful selection of atoms finally yielded the correct structure. Full-matrix least-square refinements converged to the current minimum crystallographic residual of 0.090. A computer-generated perspective drawing of the final x-ray model is shown. 1 figure.