The molecular structure and charge distribution of phorbol: parent compound of the tumor promoting phorbol diesters

The geometry of phorbol, parent compound of the very highly active tumor promoting phorbol diesters, was totally optimized starting from the crystal structure of phorbol-5-bromofuroate-chloroform solvate (Petterson et al., J. Chem. Soc. B980, 1968). The full optimization of all atomic positions was done quantum chemically using the MINDO/3 potential energy surface and a modified Davidon-Fletcher-Powell search for local minima. The molecular structure and details of the electronic charge distribution are presented.