T. A. Eggelte

Diels-Alder reaction of furan with some dienophiles

Abstract The reaction of furan and maleic acid was carried out in several solvents. The endo-adduct was isolated and the structure established by its spectral properties and conversion into known compounds. The adducts of furan with fumaric acid, diethyl fumarate and diethyl maleate are reported.

Synthesis and some reductions of endo- and exo-3,6-epoxy-Δ4-tetrahydrophthalic anhydride

Abstract The synthesis of endo-3,6-epoxy-Δ4-tetrahydrophthalic anhydride from the endo-adduct of furan and maleic acid is described. Reduction of endo- and exo-3,6-epoxy-Δ4-tetrahydrophthalic anhydride with sodium borohydride gave the corresponding lactones, while catalytic hydrogenation over 10% Pd/C gave anhydride and/or hemi-acylals, depending on the solvent.

Oxygenated γ-Butyrolactones

Abstract In connection with other studies we needed 2-(carboxymethyl)-3-hydroxycyclohexanone lactone 3a. We reasoned that 3a might be obtained from 2-(carboxymethyl)-1,3-cyclohexanedione la via conversion into enol lactone 2a followed by catalytic hydrogenation. Survey of the literature revealed that this approach had already been attempted by Rosenmund et al.2 While their reaction sequence was successful in case of the dimedone derivative lb, which was converted into 2b and 3b, the synthesis failed for la because lactonization with acetyl chloride resulted in the formation of a complex mixture of acylated compounds, which could not be characterized with certainty.

Synthesis of 9,11-epoxy-9a-homoprostaglandin analogues

Starting from Diels–Alder adducts of furan with maleic anhydride, maleic acid, and dimethyl acetylenedicarboxylate, the synthesis of prostaglandin-H1(PGH1) analogues, in which the bicyclic part of PGH1 is replaced by the 7-oxabicyclo[2.2.1]heptane moiety, is described. Isomers with the two side-chains in exo,exo-, exo,endo-, and endo,exo-positions and their C(15)-epimers have been synthesised.

Stereochemical effects in the mass spectra of endo- and exo-2,3-bismethoxycarbonylbicyclo[2.2.1]heptane and endo- and exo-2-methoxycarbonylbicyclo[2.2.1]heptane

The endo- and exo-isomers of the title compounds show markedly different behaviour upon electron impact. The molecular ion of the endo-isomer of 2,3-bismethoxycarbonylbicyclo[2.2.1]heptane (M+·212) eliminates cyclopentadiene leading to the base peak at m/e 146; this decomposition occurs to a negligible extent for the molecular ion of the exo-isomer [m/e 146 (4%; after correction for natural 13C contribution)], but expulsion of a resonance-stabilized cyclopentenyl radical is found instead, giving the base peak at m/e 145. A successive loss of methanol and carbon monoxide or keten from the molecular ion of the endo-isomer of 2-methoxycarbonylbicyclo[2.2.1]heptane (M+·154) leading to peaks at m/e 122, 94, and 80 is found. These reactions appear to be largely suppressed in the case of the corresponding exo-isomer. All these observations have been explained in terms of stereochemically controlled hydrogen migrations to the ester functions.