Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by [PMO12O40]3-[C5H5N+(CH2)15CH3]3

The 13C NMR spectra of a series of epoxides derived from endo- and exo-dicyclopentadiene and their partially hydrogenated compounds were determined to examine the substituent effects arising from the introduction of the oxirane ring in comparison with those found in other ring systems. The 13C signals of some epoxides were assigned by using lanthanide shift reagents. Characteristic substituent effects exerted by an oxirane ring were demonstrated. Marked steric γ-effects of −8—13 ppm were observed at the bridge carbon signal in the bicyclo[2.2.1]heptane skeleton. Differences were found in the substituent effects between endo- and exo-dicyclopentadiene epoxides, and have been discussed in relation to the molecular geometry.

Carbon-13 NMR spectra of some epoxides derived from dicyclopentadiene

In the presence of imidazole as an additive, a phosphorus-containing tetranuclear peroxotungstate, THA3[PO4{WO(O2)2}4] (I, THA=tetra-n-hexylammonium), could act as an efficient catalyst for epoxidation of cycloaliphatic alkenes with 30 % aqueous hydrogen peroxide (H2O2). Compound I showed higher catalytic activity and selectivity to epoxide than other tungstates. By using the I/imidazole system, various kinds of cycloaliphatic alkenes could be highly selectively converted into the acid-sensitive epoxides including industrially important diepoxides in high to excellent yields under the almost stoichiometric conditions. The 1H NMR spectroscopy showed that imidazole would work not only as a proton acceptor but also as a Lewis base to remarkably suppress the acid-catalyzed ring opening of epoxides.

Highly Selective Epoxidation of Cycloaliphatic Alkenes with Aqueous Hydrogen Peroxide Catalyzed by [PO4{WO(O2)2}4]3−/Imidazole

The last reviews devoted to the synthesis of 5-vinyl-2-norbornene and its isomerization to 5-ethylidene-2-norbornene were published in 1976–1977. The interest in the practical and theoretical aspects of this problem still does not wane, thus stimulating further investigations. A large number of patents and scientific articles have been published in the last 30 years and need to be summarized. This review elucidates the state of art of manufacture of 5-ethylidene-2-norbornene, the best third monomer for ethylene-propylene rubber. The results of new investigations concerning the manufacture of 5-vinyl-2-norbornene and its isomerization to 5-ethylidene-2-norbornene and vinylnortricyclene are considered. The most active base and coordination catalysts that have found application in industry are characterized. The mechanisms and stereochemistry of 5-vinyl-2-norbornene isomerization are discussed.

Vinylnorbornene: Preparation, chemical transformations, and use in organic synthesis and polymer chemistry. Vinylnorbornene synthesis and isomerization to ethylidenenorbornene (Review)

This work describes an experimental kinetic study and the development of a kinetic model for the dimerization of cyclopentadiene (CPD) to dicyclopentadiene (DCPD) in multicomponent reaction mixture...

Cyclopentadiene Dimerization Kinetics in the Presenceof C 5 Alkenes and Alkadienes

Diels-Alder reactions between cyclopentadiene (CP) and butadiene (BD) give a variety of dimers such as 4-vinyl-cyclohexene (VCH), 5-vinyl-2-norbornene (VNB), cis-3a, 4, 7, 7a-tetrahydroindene (THI) and dicyclopentadiene (DCP), and these dimers contain two double bonds of different reactivity.In the present investigation, the epoxidation of these dimers with hydrogen peroxide catalyzed by metal oxides such as SeO2, H2MoO4 and H2WO4 was carried out under various reaction conditions, and the results obtained were compared with those of epoxidation with organic peracids.The reaction of VCH (1) with hydrogen peroxide catalyzed by SeO2 at 40°C for 5hr [Eq. (1)] did not give an epoxide but diol (2) in a 40% yield. In the oxidation of VCH by H2MoO4 and H2WO4 catalysts, diol (2) was also obtained but in lesser yields than by SeO2 catalyst.The epoxidation of VNB (3) with hydrogen peroxide by SeO2 yielded 33% monoepoxide (4), but H2MoO4 and H2WO4 catalysts were less selective [Eq. (2)].When THI (5) was epoxidized with hydrogen peroxide by SeO2 catalyst, monoepoxide (6) and indene (7) were obtained in 27% and 8% yields, respectively [Eq. (3)], while in the epoxidation by H2MoO4 and H2WO4 catalysts only (6) resulted in yields from 10 to 15%.On the other hand, the epoxidation of THI with perbenzoic acid yielded monoepoxides (6) and (8) in a 4:5 molar ratio and diepoxide (9) [Eqs. (4) and (5)].It was found that the present catalytic epoxidation indicated a higher selectivity for the epoxidation of THI compared with that of epoxidation with perbenzoic acid.For the formation of indene (7), it seems reasonable to assume that dehydrogenation is generally observed in the oxidation of cyclic compounds using SeO2.The epoxidation of DCP (10) occurred readily without any side reactions except when a V2O5 catalyst was used to give monoepoxides (11) and (12) as shown in Eq. (6).Effects of various solvents were examined in the reactions with the SeO2 catalyst, and it was found that epoxidation proceeded rapidly in a protonic solvent having a lower polarity such as tert-butyl alcohol.An extremely high ratio of (11)/(12) as compared with that of epoxidation by organic peracid was observed with the catalysts used. It is assumed that such high regioselectivity may be attributable to a steric effect established between the bridge head proton of the norbornene ring in DCP and the epoxidizing agent.

https://www.jstage.jst.go.jp/article/jpi1958/21/6/21_6_410/_pdf

The Epoxidation of Dimers Obtained from Diels-Alder Reactions between Cyclopentadiene and Butadiene

Trimers Derived from Diels-Alder Reactions of Cyclopentadiene with Butadiene and their Carbon-13 Nuclear Magnetic Resonance Spectra

The reaction between cyclopentadiene and commercially available 1, 3-pentadiene was studied to yield principally 1:1 adducts; moreover, the stereochemistry of each component separated from the adducts was investigated with 13C-NMR spectroscopy, The norbornenetype adducts were predominantly formed under mild reaction conditions, since 1, 3-pentadiene served as a dienophile, The tetrahydroindene-type adduct gradually increased as reaction progressed owing partly to the Cope rearrangement of the norbornene-type adducts.

Diels-Alder Reaction between Cyclopentadiene and 1, 3-Pentadiene

In order to elucidate the stereochemistry of 1:2 adducts derived from the Diels-Alder reactions of cyclopentadiene and isoprene, 1:1 adducts were allowed to react with additional cyclopentadiene or isoprene. Several trimers having a norbornane or a norbornene skeleton were the predominant products, comprising more than 80% of the trimers yielded. Although a few isoprene dimers were obtained, no 1:2 adduct involving isoprene dimer was produced. The configuration of 1:2 adducts 8 through 15, except for 10 and 11, was established by means of 13C-NMR spectroscopy.

Structure of Trimers Derived from Diels-Alder Reactions between Cyclopentadiene and Isoprene

https://www.jstage.jst.go.jp/article/jpi1958/25/6/25_6_355/_pdf

Yasutaka Ishii

Papers

The Epoxidation of Dimers Obtained from Diels-Alder Reactions between Cyclopentadiene and Butadiene

Trimers Derived from Diels-Alder Reactions of Cyclopentadiene with Butadiene and their Carbon-13 Nuclear Magnetic Resonance Spectra

Diels-Alder Reaction between Cyclopentadiene and 1, 3-Pentadiene

Structure of Trimers Derived from Diels-Alder Reactions between Cyclopentadiene and Isoprene

Regioselective Oxidation of 4-Vinyl-1-Cyclohexene Catalyzed by some Mo and Se Compounds