Addition initiated ring closure: synthesis of substituted spiro[2.4]hepta-4,6-dienes via cyclopentadiene intermediates from fulvene precursors

Abstract

. 62, 2451 (1984).The reactivity of the epoxy-fulvene 1, prepared by pyrrolidine catalyzed condensation of cyclopentadiene and epoxybutanone, has been examined with various nucleophiles. It is a versatile intermediate for the preparation of spiro[2.4Jhepta-4,6-diene synthons via nucleophilic addition to the Cg position of the fulvene followed by intramolecular cyclization of the substituted cyclopentadiene anion generated in situ.

Cadmium chloride mediated regiocontrol of dienolates and ketene thioacetals: γ condensation with aldehydes

“…In spite of the previous studies in this area (referenced above) this transformation is often not as straightforward as it appears. The spiro-cyclopropyl aldehyde 1 was prepared in 84% yield by oxidation (active Mn02) of the corresponding alcohol, itself available in two steps from cyclopentadiene (20). Treatment of methyl 3-methylcrotonate (methyl 3,3-dimethylacrylate) with lithium diisopropylarnide (LDA) at -78°C in tetrahydrofuran (THF), to generate the anion, followed by condensation with aldehyde 1 afforded the a product 2 exclusively (Table 1, Entry I).…”

Radical reactions of epoxides. 2. intramolecular competition between cyclopropylmethyl and oxiranylmethyl radical ring‐opening rearrangements

“…8 ml of methanol containing 2.2ml of 30% hydrogen peroxide was prepared and cooled to 0 "C in an ice-bath. 32 To this was added dropwise 1.9 ml of aqueous 2.0 M sodium hydroxide over a 30 min period. Following this addition, the reaction was stirred for 1 h. Extraction of the reaction mixture with diethyl ether and solvent removal gave 0.69 g (80%) of l-cyclopropyl-2,3-epoxypropan-l-one.…”