Oxirane Ring Opening Reactions Research Articles

Lanthanides as lewis-acid catalysts in aldol addition,cyanohydrin-forming and oxirane ring opening reactions

Lanthanide trichlorides (Ln = La,Ce,Sm) and Eu(fod) 3 catalyze the aldol addition of silyl enol ethers to aldehydes, the addition of trimethylsilyl cyanide to aldehydes and ketones as well as thesynthesis of β-cyanosilyl ethers.

Oxirane ring opening reactions with thiols catalyzed by lanthanide complexes

LnCl 3 (Ln = Ce,Sm) and Eu(fod) 3 act as Lewis-acid catalysts in stereo- and regioselective epoxide ring opening reactions with thiols under mild conditions in CH 2Cl 2.

Crown and azacrown ethers with pendant adenine group

Base-catalyzed oxirane ring-opening reaction of 4,5-epoxy-2-oxapentyl crown ethers Ia-Ie and N-(2,3-epoxy-1-propyl) azacrown ethers IIa-IIc with adenine affords mixtures of corresponding adenin-9-yl, adenin-3-yl and adenin-7-yl derivatives (IIIa-IIIe, IVa-IVe, Va-Ve, VIa-VIc, VIIa-VIIc and VIIIa-VIIIc) respectively, separable by liquid chromatography. Structure of the individual isomers was assigned on basis of 1H, and 13C NMR spectroscopy. Compexation of the prevailing (adenin-9-yl) isomers IIIa-IIIe and VIa-VIc with sodium ion was measured potentiometrically in 99% methanol and the calculated stability constants were compared with corresponding data from related homologous series of crown and azacrown ethers IXa-IXe, Xa-Xe, XIa-XIc and XIIa-XIIc differing in pendant group.

A versatile synthesis of oligocrown compounds with hydroxyl groups at the hinge

Oxirane ring-opening reaction of N-(2,3-epoxy-1-propyl) azacrowns Ia-Ic and 4,5-epoxy-2-oxapentylcrowns IIa-IIe with mono- and diamines (including mono- and diazacrowns) afforded array of new di-, tri-, and tetracrown compounds with hydroxyl groups placed at the hinge.

Mechanism of hydrogenolysis and isomerization of oxacyloalkanes on metals, V. Selectivities of metal catalysts in ring-opening reactions of oxiranes

The deoxygenation of methyloxirane to propene and its isomerization to oxo compounds on a Ni/SiO2 catalyst were studied in a pulse microreactor, in the presence of H2 as carrier gas, at 473 K. It was found that the deoxigenation leads to the creation of new types of active centers (Lewis acid site-basic site), which cause a change in the direction of ring opening. The differences in regioselectivity observed between Ni and Cu, and Pt and Pd, can be explained by the different affinities of the metals for oxygen. This finding can be generalized to other oxygen-containing compounds.

Theoretical determination of molecular structure and conformation. 15. Three-membered rings: bent bonds, ring strain, and surface delocalization

Energy, geometry, one-electron density distribution, and Laplace concentrations of cyclopropane (l), aziridine (2), oxirane (3), cyclopropyl anion (4), protonated aziridine (5), protonated oxirane (6), halogen-bridged fluoroethyl cation (7), and hydrogen-bridged ethyl cation (8) are investigated and compared with their corresponding alicyclic counterparts. The relationship between three-membered rings (3MR) and a-complexes is demonstrated by analyzing their electron density pattern with the aid of catastrophe theory. A continuous change from 3MRs to .rr-complexes can be observed if the acceptor (donor) ability of a group X interacting with an ethylene unit is increased (decreased). The bend of the 3MR bonds is described by the curvature of the paths of maximum electron density linking the ring atoms. Interpath angles are used to evaluate the strain energy of a 3MR. A value of 75 kcal/mol is found for 1. Strain is partially compensated by stabilizing effects arising from surface delocalization of cr-electrons of the 3MR (48 kcal/mol for 1). Both ring strain and surface delocalization increase in the series 1, 2, 3 with a slight dominance of the former effect. The chemical relevance of theoretical results is discussed with regard to the ability of 3MRs to interact with mystems and to undergo addition reactions with electrophiles and nucleophiles. The observed regioselectivity in ring-opening reactions of oxiranes is explained.

A facile cleavage of oxirane with hydrazoic acid in dmf A new route to chiral β-hydroxy-α-amino acids

Chiral β-hydroxy-α-amino acids such as erythro-β-hydroxy-L-aspartic acid and erythro-β-hydroxymethyl-L-serine derivatives have been synthesized in optically pure form from L- and D-tartaric acids through a novel oxirane ring-opening reaction and a selective reduction of α-hydroxy ester as key steps.

Epoxychrysahthemic acid as an intermediate in metabolic decarboxylation of chrysanthemate insecticides

Epoxychrysanthemic acid undergoes rapid decarboxylatlon in aqueous medium at physiological pH to form a ring-opened dienol. Epoxychrysanthemates degrade in dilute acid to cyclopropane ring-opened diols. Metabolic decarboxylation of tetramethrin ( 1 ) and related chrysanthemate insecticides involves sequential enzymatic isobutenyl epoxidation, hydrolysis of the epoxychrysanthemate, and a nonenzymatic concerted decarboxylation and oxirane-ring opening reaction.

Novel copper-pyridine catalyzed ring opening reactions of aryl oxiranes. An asymmetric synthesis of (+)-indene 1,2-oxide and (+)-cis-1,2-indandiol

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNovel copper-pyridine catalyzed ring opening reactions of aryl oxiranes. An asymmetric synthesis of (+)-indene 1,2-oxide and (+)-cis-1,2-indandiolMitsuru Imuta and Herman ZifferCite this: J. Am. Chem. Soc. 1979, 101, 14, 3990–3991Publication Date (Print):July 1, 1979Publication History Published online1 May 2002Published inissue 1 July 1979https://doi.org/10.1021/ja00508a060RIGHTS & PERMISSIONSArticle Views160Altmetric-Citations15LEARN 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 (305 KB) Get e-Alerts Get e-Alerts

New Ring Opening Reactions of Oxiranes with Aryl Carboxylates

Abstract Oxiranes reacted with aryl esters in the presence of base. The reactions of aryl carboxylates with alkyloxiranes afforded almost exclusively 1-alkyl-2-(aryloxy) ethyl carboxylates, whereas the reactions with aryloxiranes gave a mixture of 1-aryl-2-(aryloxy) ethyl carboxylates and 2-aryl-2-(aryloxy) ethyl carboxylates. Similar results were also obtained in the reaction with S-aryl thiocarboxylates and diaryl carbonates. The rate of reaction between phenyl acetate and phenoxymethyloxirane (PMO) in the presence of tributylamine (n-Bu3N) as a catalyst has been determined in the temperature range 110 to 130 °C and may be expressed by –d[PMO]⁄dt=k2[n-Bu3N]·[PMO]. The apparent activation energy calculated from the Arrhenius plots is 85.8 kj/mol. The reaction catalyzed by tributylamine is assumed to proceed through zwitter ions, n-Bu3\overset+NCH2CH(R)O− and n-Bu3\overset+NCH(R)CH2O−, which attack aryl carboxylate.