title: Total synthesis of (+)-cymbodiacetal: a re-evaluation of the biomimetic route.
abstract: A total synthesis of (+)-cymbodiacetal (1) has been completed from (R)-(+)-limonene oxide using a hetero-Diels-Alder cycloaddition as a key step. The key Diels-Alder cycloaddition proceeds with endo-selectivity (2:1, endo/exo) in quantitative yield, and the two diastereomeric spirochroman products are isolable, stable products. Furthermore, the exo- and the endo-hetero-Diels-Alder cycloaddition products (2 and 7) can be oxidized with m-CPBA to produce (+)-cymbodiacetal (1) and the C(2)-symmetric bis-hemiacetal structure 8, respectively. The isomeric hemiacetal 9 is produced in both oxidation reactions. The structures of (+)-cymbodiacetal (1), its C(2)-symmetric diastereoisomer 8, and the isomeric hemiacetal 9 were confirmed using X-ray crystallography.
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, U.K., NG7 2RD.
authors.forename: Maliha
authors.initials: M
authors.lastname: Uroos
authors.forename: William
authors.initials: W
authors.lastname: Lewis
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Blake
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Hayes
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray; D000081005:Cyclohexane Monoterpenes; D008958:Models, Molecular; D015394:Molecular Structure; D039821:Monoterpenes / Q000138:chemical synthesis* / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: D000081005:Cyclohexane Monoterpenes; D039821:Monoterpenes; C486259:cymbodiacetal; C028940:limonene-1,2-epoxide