Cyclic Epoxides Research Articles

A Convenient Synthesis of Aldehydes by Rearrangement of Cyclic Epoxides with Lithium Bromide on Alumina

Epoxides can be converted effectively to aldehydes by rearrangement with lithium bromide supported on alumina. In the case of the alicyclic epoxides, ring contracted cycloalkanecarbaldehydes can be formed. The conversion is achieved by gas-phase reaction or in toluene as solvent.

ChemInform Abstract: The Chemistry of Cyclic Vinyl Ethers. Part 4. Cyclization of Unsaturated Cyclic Vinyl Ether Epoxides.

AbstractDihydrofuran (Ia) and dihydropyran (Ib) are transformed into the unsaturated epoxides (V) which are cyclized to give the spirocyclic ketals (VI) and (VII) respectively.

A novel enantioselective cyclization of a chiral epoxide to a benzofuran system

A convenient method has been established for the stereoselective construction of a dihydrobenzofuran ring system found in several bioactive natural products. The final step of the synthesis involves the concerted and efficient intramolecular displacement of mesylate 12 to give 2′R,3′R-dihydrobenzofuran a bicyclic analog of 1. This route was based on a proposed biosynthetic pathway patterned on related rotenoids.

The Chemistry of Cyclic Vinyl Ethers 4: Cyclization of Unsaturated Cyclic Vinyl Ether Epoxides

The Chemistry of Cyclic Vinyl Ethers 4: Cyclization of Unsaturated Cyclic Vinyl Ether Epoxides

Formation of glycosides by epoxidation-ring closure of open-chain hydroxyenol ethers obtained from sugars

Z- and E-Hydroxyenol ethers, obtained from aldopentoses by a Horner–Wittig reaction, have been epoxidized using m-chloroperbenzoic acid or t-butyl hydroperoxide. A spontaneous intramolecular cyclization of the intermediate epoxides due to the free hydroxy group present in the starting enol ethers occurs, giving 1,2-trans-glycopyranosides from E-enol ethers. From Z-enol ethers, 1,2-cis-glycopyranosides are obtained, although in the case of complex aglycones the cyclization is not entirely stereospecific. The stereochemical course of both the epoxidation reaction and the pyranose ring formation from the intermediate epoxides is discussed.

ChemInform Abstract: Epoxidation of Unsaturated Macrolides: Stereocontrolled Routes to Ionophore Subunits.

AbstractThe racemic cyclohexanone (I) serves as key compound for the synthesis of the cyclic epoxide (IV), while the second cyclic epoxide (VI) is obtained from the peroxide (V).

The stereochemically controlled Horner-Wittig route to unsaturated acids: The Baeyer-Villiger rearrangement of α-(1-Ph2PO-alkyl) -cyclohexanones

Lithiated alkyl diphenylphosphine oxides attack cyclic epoxides with high stereoselectivity: Baeyer-Villiger rearrangement of the derived ketones gives Horner-Wittig intermediates for the synthesis of Z unsaturated acids.

Total synthesis of (+/-)-11 alpha-hydroxyprogesterone by cyclization of a polyunsaturated epoxide.

The total synthesis of a typical 11-hydroxylated steroid, (+/-)-11 alpha-hydroxyprogesterone, was achieved by picric acid-catalyzed tricyclization of a polyunsaturated epoxide appropriately substituted with ketal, hydroxyl, and acetylenic units. This epoxide was prepared by a multistage sequence featuring two successive alkylations of intermediary, monocyclic sulfones. The first sulfone intermediate was obtained by means of a short sequence starting from levulinic acid and diethyl succinate and involving a selective cyclization reaction.

13C Chemical shifts of long-chain epoxides, alcohols and hydroperoxides

13C-NMR shifts are reported for a number of long-chain and cyclic epoxides ( cis and trans, saturated and unsaturated) and of several primary alcohols and hydroperoxides. The influence of each of these three functional groups on the chemical shift of nearby carbons has been determined and some new additivity parameters are reported.

Synthesis of polycyclic homocyclopropylcarbinols by reductive cyclization of bromocyclopropyl epoxides

Synthesis of polycyclic homocyclopropylcarbinols by reductive cyclization of bromocyclopropyl epoxides

Attempted cyclization of an epoxide. Elimination of an epoxide

Attempted cyclization of an epoxide. Elimination of an epoxide

The preparation of a stable 8-oxatricyclo[4,3,0,07,9]nona-2,4-diene and an evaluation of its potential as a source for the photochemical generation of oxiren

The synthesis of 2-methyl-3,4,5-triphenyl-8-oxatricyclo[4,3,0,07,9]nona-2,4-diene (14) is described, the first stable member of this ring system. Preparation of (14) was achieved by reacting dibenzyl diazenedicarboxylate with 2-methyl-3,4,5-triphenylbicyclo[4,2,0]octa-2,4,7-triene (29) to form the adduct (30a), which was selectively epoxidized at the cyclobutenyl double bond with 3-chloroperbenzoic to yield the epoxide (32a). Removal of the benzyl groups (H2/Pd) from the hydrazo bridge of (32a), followed by oxidation (red mercuric oxide or hydrogen peroxide) yielded the putative azo compound (33) which spontaneously lost dinitrogen, even at -78�, to yield (14) as a crystalline solid, m.p. 128�. While (14) has the potential to undergo 1,2-photoaromatization to yield oxiren (4a), this is not realized and ring-opening to the cyclic epoxide (34) is the major photochemical reaction observed under various ultraviolet irradiation conditions. Isomerization of (14) into (34) also occurs under thermal conditions. The 1H n.m.r, spectra of (14) as well as its trapping with dienophiles is discussed.

Epoxyannulation II: Cyclization of ω-ketosulfonium salts

Treatment of 1,5 or 1,6 ketosulfonium salts with potassium t-butoxide has yielded cyclic epoxides of high stereochemical purity in good yield.

Low temperature metallation of cyclic epoxides: enhancement of carbene derived insertion reaction

Low temperature metallation of cyclic epoxides: enhancement of carbene derived insertion reaction

Oxidosqualene cyclization in human placenta: An easy step of sterol biosynthesis

Squalene epoxide cyclization, a step in cholesterol biosynthesis, was studied by incubation of [2- 14C]squalene-2(3)-epoxide with human placental microsomes; squalene epoxide cyclization was found to be just as efficient as with rat liver microsomes. Thus, in the human placenta squalene to lanosterol conversion is limited by the rate of squalene epoxidation, but this is not accompanied by squalene accumulation.

Cyclization of a terpenoid diene with preformed A-B-D rings and its significance for the mechanism of terpenoid terminal epoxide cyclizations

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCyclization of a terpenoid diene with preformed A-B-D rings and its significance for the mechanism of terpenoid terminal epoxide cyclizationsE. E. Van Tamelen, R. G. Lees, and A. GriederCite this: J. Am. Chem. Soc. 1974, 96, 7, 2255–2256Publication Date (Print):April 1, 1974Publication History Published online1 May 2002Published inissue 1 April 1974https://doi.org/10.1021/ja00814a047RIGHTS & PERMISSIONSArticle Views70Altmetric-Citations12LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (267 KB) Get e-Alerts Get e-Alerts

The Synthesis of Tricyclo [4. 2. 2. 02, 5] Deca-3, 7, 9-Trienes and Related Derivatives Via the Kolbe Oxidation Route

Abstract The Koloe oxidation of cis-dicarboxylic acids is a convenient method for clafin synthesis 1,2,3. In an earlier communication 1 one of us reported the synthesis of Tryicyclo [4.2.2.02,5] deca-3,7,9-triane (Nenitzescu's hydrocarbon) by this method. In view of the interest in the (CH)10 energy surface, any entry at the C10H10 level immediately malcas & wide range of ring structure potentially available. 4 For this reason we have chosen to concentrate on the tricyclo[4.2.2.02,5] deca-3,5,7-triane system and now report the results of a series of compounds containing various functional groups which prove to be stable under the reaction conditions. These now include phosphine oxide35, cyclic ether 3g, nitrile1, ester1, vinyl bromide, vincinal dibromide, methoxy, ketone and epoxide group (See table).

The analysis of 1,2‐epoxyalkanes by gas liquid chromatography

AbstractTerminal epoxides react quantitatively with methanol in the presence of boron trifluoride to give both primary and secondary hydroxy methyl ethers. These derivatives are useful in the analysis of terminal epoxide mixtures by gas liquid chromatography. This procedure is compared with the conventional method and with a procedure in which the 1,2‐epoxyalkanes are reduced to the corresponding secondary alcohols with LiAlH4. A statistical analysis of experimental data obtained from known mixtures of long chain epoxides is described. Results of this analysis demonstrate the improved accuracy and precision of the method as compared to the other methods investigated. LiAlH4 reduction is the preferred method of analysis for the more reactive epoxides as well as for the cyclic epoxides. This procedure is particularly useful in the analysis of epoxides containing a tertiary carbon atom. The application of this technique to other epoxides is expected to improve their analysis, but further work is necessary.

Olefin Alkylation in Biosynthesis

AbstractStereochemical studies, made possible by asymmetric labeling with hydrogen isotopes, have led to the hypothesis that enzymic association of C5 units in polysoprenoid synthesis is not a concerted process but proceeds in two steps: a trans 1,2‐addition to an olefin followed by a trans 1,2‐elimination. It is shown that similar mechanisms can also explain the cyclization of squalene epoxide to tetracyclic and pentacyclic triterpenoids.

Laboratory cyclization of geranylgeranyl acetate terminal epoxide.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLaboratory Cyclization of Geranylgeranyl Acetate Terminal EpoxideE. E. van Tamelen and R. G. NadeauCite this: J. Am. Chem. Soc. 1967, 89, 1, 176–177Publication Date (Print):January 1, 1967Publication History Published online1 May 2002Published inissue 1 January 1967https://doi.org/10.1021/ja00977a052RIGHTS & PERMISSIONSArticle Views211Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (259 KB) Get e-Alerts Get e-Alerts