title: Intramolecular oxonium ylide formation-[2,3] sigmatropic rearrangement of diazocarbonyl-substituted cyclic unsaturated acetals: a formal synthesis of hyperolactone C.
abstract: Rh(II)-catalyzed oxonium ylide formation-[2,3] sigmatropic rearrangement of α-diazo-β-ketoesters possessing γ-cyclic unsaturated acetal substitution, followed by acid-catalyzed elimination-lactonization, provides a concise approach to 1,7-dioxaspiro[4.4]non-2-ene-4,6-diones. The process creates adjacent quaternary stereocenters with full control of the relative stereochemistry. An unsymmetrical monomethylated cyclic unsaturated acetal leads to hyperolactone C, where ylide formation-rearrangement proceeds with high selectivity between subtly nonequivalent acetal oxygen atoms.
authors.affiliation: Department of Chemistry, Chemistry Research Laboratory, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K.
authors.forename: David M
authors.initials: DM
authors.lastname: Hodgson
authors.forename: Stanislav
authors.initials: S
authors.lastname: Man
authors.forename: Kimberley J
authors.initials: KJ
authors.lastname: Powell
authors.forename: Ziga
authors.initials: Z
authors.lastname: Perko
authors.forename: Minxiang
authors.initials: M
authors.lastname: Zeng
authors.forename: Elena
authors.initials: E
authors.lastname: Moreno-Clavijo
authors.forename: Amber L
authors.initials: AL
authors.lastname: Thompson
authors.forename: Michael D
authors.initials: MD
authors.lastname: Moore
mesh_terms: D000080:Acetals / Q000737:chemistry*; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009861:Onium Compounds / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013141:Spiro Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000080:Acetals; D005663:Furans; D009861:Onium Compounds; D013141:Spiro Compounds; C488315:hyperolactone C; C027727:hydronium ion; D012238:Rhodium