SYNTHESIS, BIOTRANSFORMATION AND STEREOCHEMISTRY OF 6β-SESQUITERPENE LACTONES: SYNTHESES OF 6β-ARTEPAULIN, 11,13-DIHYDRO-6β-TUBERIFERIN, 5,15-DIHYDRO-6β-OOPODIN, 4-EPI-6β-VULGARIN AND 6β-VULGARIN

Article abstract of DOI:10.1016/S0040-4020(01)87881-9

6β-Artepaulin, 11,13-dihydro-6β-tuberiferin, 4,15-dihydro-6β-oopodin, 4-epi-6β-vulgarin and 6β-vulgarin were obtained from α-santonin.Stereochemical studies showed that the configuration at C-6 is decisive in the chemical behaviour of the A ring.Biotransformation of 1-oxo-5,6α,4,11βH-eudesm-2-en-6,12-olide with Rhizopus nigricans cultures probed to be a very efficient alternative way to obtain 4-epi-6β-vulgarin, which was then converted to 6β-vulgarin, a convenient starting material for biogenetical studies of pseudoguaianolides.A new 8β-hydroxyl derivative obtained from this biotransformation constitutes a new approach to the synthesis of 8,12-eudesmanolides and other sesquiterpenolides.Molecular structures were determined mainly by mono- and bidimensional nmr experiments.