| Abstract
| - Ketobutenolide 3, easily obtained from santonin(1), has been transformed into two naturalfuranoeudesmanes 4 and 5, isolated fromCommiphora molmol and Tubipora musica,respectively.trans- And cis-decalin systems were obtainedby stereoselective reduction of the C4−C5double bondin 3 in the following way: hydrogenation of 3over Pd/C followed by acidic treatment gave thecisisomer 10 as the major product; selective hydrogenation ofthe C1-C2 double bond with theWilkinson’s catalyst followed by reduction with NaTeH yielded mainlythe trans isomer 9.Compounds 9 and 10 were transformed into4 and 5 in parallel sequences. Opticalrotation andCD measurements of the synthetic products revealed that thestereochemistry of both naturalproducts should be revised to their enantiomeric form.
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