title: Stereoselective Synthesis of 8,12-Furanoeudesmanes from Santonin. Absolute Stereochemistry of Natural Furanoeudesma-1,3-diene and Tubipofurane.
abstract: Ketobutenolide 3, easily obtained from santonin (1), has been transformed into two natural furanoeudesmanes 4 and 5, isolated from Commiphora molmol and Tubipora musica, respectively. trans- And cis-decalin systems were obtained by stereoselective reduction of the C(4)-C(5) double bond in 3 in the following way: hydrogenation of 3 over Pd/C followed by acidic treatment gave the cis isomer 10 as the major product; selective hydrogenation of the C(1)-C(2) double bond with the Wilkinson's catalyst followed by reduction with NaTeH yielded mainly the trans isomer 9. Compounds 9 and 10 were transformed into 4 and 5 in parallel sequences. Optical rotation and CD measurements of the synthetic products revealed that the stereochemistry of both natural products should be revised to their enantiomeric form.
authors.affiliation: Departament de Química Orgànica, Facultat de Química, Universitat de València, E- 46100 Burjassot (València), Spain.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Blay
authors.forename: Luz
authors.initials: L
authors.lastname: Cardona
authors.forename: Begoña
authors.initials: B
authors.lastname: García
authors.forename: José R.
authors.initials: JR
authors.lastname: Pedro
authors.forename: Juan J.
authors.initials: JJ
authors.lastname: Sánchez