title: Rearrangement of 4,5-epoxy-9-trimethylsilyldecalines. Application to the synthesis of the natural eremophilane (-)-aristolochene.
abstract: Several 4,5-epoxy-9-trimethylsilyl-eudesmanes and 15-nor-eudesmanes, having different relative stereochemistry and substitution at the oxirane ring, have been prepared starting from (-)-carvone and subjected to acid-promoted rearrangement. The presence of the silicon at C9 favors two different main reaction pathways involving C14-methyl or C1-methylene migration through the stabilization of a C10 carbocation intermediate. Selective 1,2-migration of the bridgehead methyl group takes place with trisubstituted beta-epoxide and tetrasubstituted alpha-epoxide, yielding 4-hydroxy-eremophilane and 15-nor-eremophilane compounds, while the trisubstituted alpha-epoxide suffers successive rearrangements to give a 1-hydroxy-15-nor-eremophilane through a pathway involving the initial migration of the C1 methylene. The synthetic utility of these rearrangements is shown by the synthesis of natural (-)-aristolochene.
authors.affiliation: Departament de Química Orgànica, Facultat de Química, Universitat de València, 46100 Burjassot (València), Spain.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Blay
authors.forename: Luz
authors.initials: L
authors.lastname: Cardona
authors.forename: Ana M
authors.initials: AM
authors.lastname: Collado
authors.forename: Begoña
authors.initials: B
authors.lastname: García
authors.forename: José R
authors.initials: JR
authors.lastname: Pedro
mesh_terms: D008968:Molecular Conformation; D009281:Naphthalenes / Q000138:chemical synthesis / Q000737:chemistry*; D012717:Sesquiterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D009281:Naphthalenes; D012717:Sesquiterpenes; C054277:aristolochene