title: Synthesis of the C10-C24-bis-spiroacetal core of 13-desmethyl spirolide C based on a sila-Stetter-acetalization process.
abstract: Synthesis of the bis-spiroacetal core of 13-desmethyl spirolide C has been completed based on a sila-Stetter-acetalization process. The acylsilane and enone partners in the Stetter reaction were prepared in 7 and 11 steps, respectively, from (S) and (R)-aspartic acid. The quaternary center at C19 in the enone moiety was controlled by relying on the Seebach's chiral self-reproduction method using an enantiopure (S)-lactic acid based dioxolanone. The final acid-catalyzed spiroacetalization provided the desired spiroacetal as a mixture of diastereoisomers in 13 linear steps. Whatever the conditions used, the non-natural transoid isomer was formed preferentially. However, both cisoid and transoid isomers were isolated pure and their structure assigned unambiguously through NMR spectroscopic studies.
authors.affiliation: University of Bordeaux, 351, Cours de la libération, 33405 Talence Cedex (France), Fax: (+33) 5-40-00-62-86.
authors.forename: Jessica
authors.initials: J
authors.lastname: Labarre-Lainé
authors.forename: Ignacio
authors.initials: I
authors.lastname: Periñan
authors.forename: Valérie
authors.initials: V
authors.lastname: Desvergnes
authors.forename: Yannick
authors.initials: Y
authors.lastname: Landais
mesh_terms: D000080:Acetals / Q000737:chemistry*; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C517170:13-desmethylspirolide C; D000080:Acetals; D013141:Spiro Compounds
keywords: acetalization; bis-spiroacetal; organic synthesis; sila-Stetter reaction; silicon