IMPROVED ACCESS TO HIGHLY UNSATURATED SKIN IRRITANTS OF THE DAPHNANE TYPE FROM LATEX OF EXCOECARIA-OPPOSITIFOLIA

A new and more efficient procedure was developed to obtain 5 beta-hydr oxyresiniferonol-6 alpha,7 alpha-epoxide-9,13,14-ortho(2,4,6-decatrien oate) [Excoecaria factor 01] by alkaline transesterification of corres ponding 20-ester(s) genuinely present in latex of Excoecaria oppositif olia. It was obtained in a 10-fold better yield than previously, proba bly due to speeding up the separation procedures of the sensitive comp ound. 01 is an appropriate starting material for the preparation of th e daphnane prototype irritant and tumor-promoting orthoester simplexin (SIM) especially of a multiple tritium-labeled form thereof. Moreover , a new Excoecaria factor O3, i.e. the 9,13,14-ortho(2,4,6,8-hexadecat etraenoate) of 5 beta,12 beta-dihydroxyresiniferonol-6 alpha,7 alpha-e poxide was isolated after alkaline transesterification of a TLC-unifor m fraction, composed of corresponding 20-ester(s).