Haruhiko Tada

Structure of the sesquiterpene lactone laurenobiolide

A new germacranolide, laurenobiolide, has been isolated from Laurus nobilis L. and its stereostructure was elucidated on the basis of the spectroscopic data for the lactone and for some reaction products.

Cytotoxic hydroxypolygodials. X-Ray molecular structure of (1R,3S,5aS,-9aS,9bR)-1,3,5,5a,6,7,8,9,9a,9b-decahydro-1,3-dimethoxy-6,6,9a-trimethylnaphtho[1,2-c]furan

Hydroxypolygodials, designed to have the simplified structure of the cytotoxic sesterterpene deacetylscalaradial isolated from the marine sponge Cacospongia scalaris, were synthesized starting from polygodial via fungal hydroxylation and chemical modification, and the expected biological activities were obtained. All the structures of the products were determined by mainly spectroscopic means. A simple method for removal of chlorophyll was devised, resulting in considerable improvement in the yield of polygodial.

Simultaneous application of the nuclear Overhauser effect and an N.M.R. shift reagent. Conformation of costunolide and dihydrocostunolide in solution

Conformations of the ten-membered ring sesquiterpene lactones costunolide (1) and dihydrocostunolide (2) in [2H]chloroform have been determined by intramolecular inter-nuclear Overhauser effect measurements in the presence of an n.m.r. lanthanide shift reagent, [2H27]Eu(fod)3; care must be taken in applying these techniques simultaneously.