Nucleophilic Ring Opening Of Epoxides Research Articles

ZrCl4 as a new and efficient catalyst for the opening of epoxide rings by amines

Zirconium(IV) chloride catalyses the nucleophilic opening of epoxide rings by amines leading to the efficient synthesis of β-amino alcohols. The reaction works well with aromatic and aliphatic amines in short times at room temperature in the absence of solvent. Exclusive trans stereoselectivity is observed for cyclic epoxides. Aromatic amines exhibit excellent regioselectivity for preferential nucleophilic attack at the sterically less hindered position during the reaction with unsymmetrical epoxides. However, in case of styrene oxide, selective formation of the benzylic amine was observed during the reactions with aromatic amines. Graphic

Zinc-catalyzed aminolysis of epoxides

A series of amino alcohols has been prepared by a novel zinc-catalyzed nucleophilic opening of epoxide rings by amines.

ChemInform Abstract: Aminopropyl Silica Gel Supported Iodine as Catalyst in Nucleophilic Ring Opening of Epoxides and Episulfides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Chemoenzymatic Synthesis of All Four Cytoxazone Stereoisomers

Racemic cytoxazone (±-5) was synthesized starting from easily available glycidic ester (±)-1 by nucleophilic epoxide ring opening, followed by 2-oxazolidinone ring construction and calcium chloride/sodium borohydride reduction of the intermediary ester (±)-4. Kinetic resolution of (±)-5 performed by acetylation with vinyl acetate catalyzed by Penicillium camemberti lipase (PcamL) afforded, on hydrolysis of acetate (-)-6, cytoxazone (-)-5 in 33% overall yield and 88.2% enantiomeric excess (ee), and its enantiomer (+)-5 (38% yield, 89.3% ee). Base-catalyzed epimerization of intermediary (±)-4 to (±)-7, and reduction and kinetic resolution with Candida antarctica lipase (CAL) led to epi-cytoxazones (-)-8 and (+)-8.

What about BOB? A synthetically useful protecting group

Benzyloxybutyryl (BOB) esters of alcohols can be prepared from commercially available 4-benzyloxybutyric acid by standard acylation techniques, by the Mitsunobu reaction (with inversion of configuration), or by the Jacobsen asymmetric nucleophilic ring opening of epoxides. BOB esters can be removed selectively in the presence of other esters under conditions that are compatible with a variety of sensitive functional groups.

ChemInform Abstract: Fluorinated Epoxides. Part 5. Highly Selective Synthesis of Diepoxides from α,ω‐Diiodoperfluoroalkanes. Regioselectivity of Nucleophilic Epoxide‐Ring Opening and New Amphiphilic Compounds and Monomers.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Iron(III) Trifluoroacetate as an Efficient Catalyst for Solvolytic and Nonsolvolytic Nucleophilic Ring Opening of Epoxides

Abstract Iron(III) trifluoroacetate was used as an efficient and nonhygroscopic catalyst for the alcoholysis, hydrolysis, and acetolysis of epoxides. The addition of chloride, bromide, iodide, and nitrate ions to epoxides to produce the corresponding 2-halo and 2-nitratoalkanols and also the conversion of epoxides to acetonides and thiiranes were also performed efficiently in the presence of this catalyst.

Fluorinated epoxides: 5. Highly selective synthesis of diepoxides from α,ω-diiodoperfluoroalkanes. Regioselectivity of nucleophilic epoxide-ring opening and new amphiphilic compounds and monomers

An improved procedure for the radical addition of α,ω-diiodoperfluoroalkanes I–(CF 2CF 2) n –I ( n = 2, 3) to allyl acetate that afford the corresponding bis-adducts AcOCH 2CHICH 2(CF 2CF 2) n CH 2CHI–CH 2OAc ( 2a– 2b) has been developed. The primary bis-adducts 2a– 2b suffered a subsequent rearrangement in the addition mixture to afford semi-rearranged adducts AcOCH 2CHICH 2–(CF 2CF 2) n –CH 2CH–(OAc)CH 2I ( 3a– 3b) in an amount of ca. 15% rel. at reaction temperatures. Both adducts 2a– 2b and rearranged adducts 3a– 3b were converted to diepoxides CH 2(–O–)CHCH 2(CF 2CF 2) n CH 2CH–(–O–)CH 2 ( 4a– 4b) with high chemoselectivity in two ways: the selectivity of the direct epoxidation of 2a– 2b and/or 3a– 3b with potassium hydroxide was extremely dependent on the solvent; the second method included hydrolysis of 2a– 2b and/or 3a– 3b to bis-iodohydrins 5a– 5b and 6a– 6b that were easily transformed to the diepoxides 4a– 4b. Ring-opening reactions of bis-epoxides 4a– 4b with hydroxy compounds in the presence of boron trifluoride etherate took place at the terminal carbon atom of both epoxide rings with complete regioselectivity. A convenient transformation of the diepoxides to the corresponding amphiphilic tetrols ( 14a– 14b) via dioxolane intermediates was accomplished with overall yields of 57–65% . Base-catalyzed ring-opening by methacrylic acid was not completely regioselective (89% terminal attack on both oxirane rings) and afforded a mixture of regioisomeric bis-methacrylates ( 16a– 16b and 17a– 17b) bearing two hydroxyl groups. In contrast, epoxide ring-opening with morpholine was completely regioselective in both diepoxides 4a and 4b.

TiCl3(OTf) and TiO(TFA)2 Efficient Catalysts for Ring Opening of Epoxides with Alcohols, Acetic Acid and Water

TiCl3(OTf) and TiO(TFA)2 can efficiently catalyze nucleophilic ring opening of epoxides in primary, secondary and tertiary alcohols, acetic acid and water to give the corresponding β-alkoxy alcohols, β-acetoxy alcohols and vicinal diols with high stereo- and regioselectivity in excellent yields. The reaction of optically active styrene oxide in MeOH with two titanium reagents was found to be highly stereospecific and afforded the corresponding S-(+)-2-methoxy-2-phenyl ethanol in 89-95% ee.

ChemInform Abstract: Regioselective Nucleophilic Ring Opening of Epoxides and Aziridines Derived from Homoallylic Alcohols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Regioselective nucleophilic ring opening of epoxides and aziridines derived from homoallylic alcohols

The regioselectivity of nucleophilic ring opening of some 3,4-epoxy and 3,4-aziridino alcohols has been studied. The nucleophiles chosen were complex hydrides (LiAlH 4, Red-Al and DIBAL) and Lipshutz- or Gilman-type organocuprate reagents. The C-4 substituent in the substrates was varied in order to study steric and electronic effects on the ring opening reactions. For alkyl substituents at C-4, most of the results can be explained on the basis of intramolecular delivery of the nucleophile to C-3 via a six-membered transition state, leading to 1,4-diols or 1,4-amino alcohol derivatives. In general, the epoxy alcohols gave poorer regioselectivity than the N-tosyl aziridino alcohols, for which selectivities of >95:5 were routinely obtained. The activating effect of a phenyl group at C-4 led to a switch in regiochemistry, with the 1,3-diol or 1,3-amino alcohol derivative as the major product.

Studies on propafenone-type modulators of multidrug-resistance IV1): synthesis and pharmacological activity of 5-hydroxy and 5-benzyloxy derivatives.

A series of 5-hydroxy and 5-benzyloxy analogs of the antiarrhythmic and multidrug resistance (MDR) modulating drug propafenone was synthesized and the MDR-modulating activity of the compounds was evaluated using a daunomycin efflux assay system. The key step of the synthesis is the selective reduction of the double bond in 1 without cleavage of the benzyl group thus leading to the phenol 3. Alkylation with epichlorohydrine followed by nucleophilic epoxide ring opening gave the benzylated target compounds 5a-d. Subsequent cleavage of the benzyl group gave the 5-hydroxy analogs 6a-d. Structure activity relationship studies showed, that the 5-hydroxy derivates 6a-d fit the log P/log potency correlation line previously established for a series of propafenone analogs. In contrast, all four 5-benzyloxy analogs 5a-d showed almost identical EC50 values, independent of their log P value.

On the Mechanism of Asymmetric Nucleophilic Ring-Opening of Epoxides Catalyzed by (Salen)CrIII Complexes

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOn the Mechanism of Asymmetric Nucleophilic Ring-Opening of Epoxides Catalyzed by (Salen)CrIII ComplexesKarl B. Hansen, James L. Leighton, and Eric N. JacobsenView Author Information Department of Chemistry and Chemical Biology Harvard University Cambridge, Massachusetts 02138 Cite this: J. Am. Chem. Soc. 1996, 118, 44, 10924–10925Publication Date (Web):November 6, 1996Publication History Received29 July 1996Published online6 November 1996Published inissue 1 January 1996https://doi.org/10.1021/ja962600xCopyright © 1996 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views6294Altmetric-Citations352LEARN 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 Read OnlinePDF (116 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Azides,Catalysts,Ethers,Ring opening reactions,Stereoselectivity Get e-Alerts

Nucleophilic Ring Opening of Epoxides by Organolithium Compounds: Ab Initio Mechanisms

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNucleophilic Ring Opening of Epoxides by Organolithium Compounds: Ab Initio MechanismsSjoerd Harder, Joop H. van Lenthe, Nicolaas J. R. van Eikema Hommes, and Paul v. R. SchleyerCite this: J. Am. Chem. Soc. 1994, 116, 6, 2508–2514Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://doi.org/10.1021/ja00085a035RIGHTS & PERMISSIONSArticle Views1042Altmetric-Citations32LEARN 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 (732 KB) Get e-Alerts Get e-Alerts

Polymer-supported ceric(IV) catalyst: 1. Catalytic ring opening of epoxides

Poly(vinyl pyridine)-supported ceric(IV) complex can be easily prepared. It catalyses nucleophilic ring opening of epoxides in alcohols under mild conditions with high regio- and stereoselectivity. The reaction work-up is easy and the catalyst can be reused several times without its activity changing appreciably. Regeneration of the catalyst is easily achieved.

ChemInform Abstract: Solid Base‐Directed Regioselective Ring Opening of Epoxides with Cyanotrimethylsilane.

Calcium oxide and magnesium oxide are found to be effective solid bases for nucleophilic ring opening of epoxides with cyanotrimethylsilane to afford β-trimethylsiloxy nitriles in a highly regioselective manner without any contamination of isocyanides.

Mild, Efficient and Selective Opening of Epoxides with Alcohols Catalyzed by Ceric(IV) Ammonium Nitrate

Abstract Commercially available Ceric(IV) Ammonium Nitrate (CAN) catalyzes nucleophilic ring opening of epoxides in primary, secondary and tertiary alcohols under mild conditions. The corresponding β-alkoxy-alcohols were obtained with high regio and stereoselectivity in high yields.

Solid Base-directed Regioselective Ring Opening of Epoxides with Cyanotrimethylsilane

Abstract Calcium oxide and magnesium oxide are found to be effective solid bases for nucleophilic ring opening of epoxides with cyanotrimethylsilane to afford β-trimethylsiloxy nitriles in a highly regioselective manner without any contamination of isocyanides.

Über die bevorzugte Bildung von trans‐Epoxiden bei der Technetiumkatalysierten Flüssigphasenoxidation von cis/trans‐n‐Alkenen

About the Formation of trans‐Epoxides in the Liquid Phase Oxidation of cis/trans‐n‐Alkenes Catalyzed by TechnetiumThe liquid‐phase oxidation of n‐oct‐1‐ene, cis‐oct‐4‐ene and cis/trans mixtures of oct‐4‐ene with molecular oxygen in the presence of the technetium complexes 1 to 10 was studied. Low epoxide yields (≦10%) are characteristic features of the reactions. Pure cis‐oct‐4‐ene and mixtures of cis/trans‐oct‐4‐ene yields in cis/trans‐epoxide ratios lower than 0.05. Isomerization reactions and nucleophilic epoxide ring opening reactions are not responsible for the low epoxide yield and the favoured formation of trans‐epoxide. Epoxide decomposition by a Tc‐catalyzed radical reaction which prefers the cis‐epoxide is discussed.

Nucleophilic ring opening of epoxides by carbanions : Novel formation of cyclopropane derivatives in a non-polar solvent

Nucleophilic ring-opening of epoxides 2( a-d) with carbanions of different steric requirements under refluxing benzene afforded a single stereoisomer of the cyclopropane derivatives 4. The same reaction under refluxing ethanol gave the normal products, i.e. the trans-lactones 6. Mechanism and high stereoselectivity observed in the novel cyelopropane formation, and regiospecific cleavage of the cyclopropane carboxylic acids (in 4) have also been discussed in detail.