title: Synthesis of the bis-spiroacetal moiety of spirolides B and D.
abstract: An enantioselective synthesis of the bis-spiroacetal fragment of spirolides B and D is reported. The carbon framework was constructed via Barbier reaction of dihydropyran 3 with aldehyde 4, followed by a double oxidative radical cyclization to construct the bis-spiroacetal. A silyl-modified Prins cyclization and enantioselective crotylation successfully installed the stereocenters in the cyclization precursor. The initial unsaturated bis-spiroacetals 2a-d underwent equilibration during epoxidation to trans-epoxide 14 that was converted to a tertiary alcohol. [reaction: see text]
authors.affiliation: Department of Chemistry, University of Auckland, 23 Symonds Street, Auckland, New Zealand.
authors.forename: Kai
authors.initials: K
authors.lastname: Meilert
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Brimble
mesh_terms: D000080:Acetals / Q000138:chemical synthesis* / Q000737:chemistry; D000818:Animals; D003500:Cyclization; D015394:Molecular Structure; D008974:Mollusca / Q000737:chemistry; D010084:Oxidation-Reduction; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000080:Acetals; D013141:Spiro Compounds; C467770:spirolide B; C467769:spirolide D