Chemoselective Ring Opening Of Epoxides Research Articles

Synthesis, characterization and catalytic application of Bi2S3 microspheres for Suzuki-Miyaura cross-coupling reaction and chemoselective ring opening of epoxides

Bismuth sulfide (Bi2S3) prepared using l-cysteine, which served as both the sulfur source and the directing molecule for the formation of Bi2S3 as heterogeneous catalyst through solvothermal method. The prepared catalyst was examined by various techniques such as XRD, BET, FE-SEM, TEM, and TGA analysis. The results and analysis revealed that bismuth microspheres have better catalytic behavior for the preparation of biphenyl in water as a greenest solvent and for the ring opening of epoxides by nucleophiles including amines, alcohol, and thiol compared to pure Bi(NO3)3. 3H2O under solvent-free condition. Moreover, the novel catalyst could be recovered and reusedat least four times without loss of its catalytic activity.

The base-free chemoselective ring opening of epoxides with carboxylic acids using [bmim]Br: a rapid entry into 1,2-diol mono-esters synthesis

A facile and highly convenient base-free protocol for the chemoselective preparation of 1,2-diol mono-esters is described. In this method, the regioselective ring opening of epoxides with carboxylic acids in the presence of [bmim]Br furnishes the corresponding 1,2-diol mono-esters in excellent yields. This method is efficient for various structurally diverse epoxides and carboxylic acids and it can be efficiently applied for the scale up synthesis of 1,2-diol mono-esters in reasonable to good yields. [bmim]Br remarkably influences the reaction progress and acts as both solvent and catalyst in this protocol.

Efficient Synthesis of β-Hydroxy Sulfides and β-Hydroxy Sulfoxides Catalyzed by Cu/MgO Under Solvent-Free Conditions

Regio-, stereo-, and chemoselective ring opening of epoxides with thiols using Cu/MgO as a heterogeneous catalyst has efficiently been carried out to produce the corresponding β-hydroxy sulfides in excellent yields at room temperature under solvent-free conditions. The treatment of the epoxides with thiols and 50% aqueous H2O2 in the presence of the same catalyst at room temperature affords the β-hydroxy sulfoxides in excellent yields.

ChemInform Abstract: Observations on the Use of Triphenylphosphonium Bromide as a Mild and Quantifiable Source of Hydrogen Bromide for Chemoselective Ring Opening of Epoxides to Bromohydrins.

The chemoselective ring opening of epoxides to bromohydrins in the presence of ketal, benzyloxymethoxy and trimethylsilyl ether functionality using triphenylphosphonium bromide is described. The preparation of a polymer supported variant is also reported.

Bismuth(III) Trifluoromethanesulfonate and Trifluoroacetate as Convenient and Efficient Catalysts for Regio‐ and Chemoselective Ring Opening of Epoxides in Reactions with Anilines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Bismuth(III) trifluoromethanesulfonate and trifluoroacetate as convenient and efficient catalysts for regio- and chemoselective ring opening of epoxides in reactions with anilines

Bismuth(III) trifluoromethanesulfonate and trifluoroacetate are highly efficient and practical catalysts for oxirane ring opening in reactions of epoxides with substituted anilines. The reactions are characterized by high chemoselectivity and good to excellent yields of the products.

σ–π Chelation-controlled chemoselective ring openings of epoxides

The chemoselective ring opening of alkynyl epoxides in the co-existence of the corresponding alkyl epoxides is achieved in the Me3Al mediated reaction with alkynyllithium reagents. The observed interesting chemoselectivity is most probably a reflection of bidentate complexation of the Lewis acid to an n-electron of an oxygen atom of the epoxide and π-electrons of the CC triple bond.

Observations on the Use of Triphenylphosphonium Bromide as a Mild and Quantifiable Source of Hydrogen Bromide for Chemoselective Ring Opening of Epoxides to Bromohydrins

The chemoselective ring opening of epoxides to bromohydrins in the presence of ketal, benzyloxymethoxy and trimethylsilyl ether functionality using triphenylphosphonium bromide is described. The preparation of a polymer supported variant is also reported.

Liquid-phase organic reactions catalyzed by inorganic solid acids and bases

CaO and MgO as strong solid bases catalyzed the regio- and chemoselective ring opening of epoxides with Me 3SiCN at room temperature much more efficiently than homogeneous promoters. On CaO and MgO, the reactions of unsymmetrical epoxyalkanes with Me 3SiCN afforded exclusively 3-trimethylsiloxy-alkanenitriles in high yields. On CaO, 2,3-epoxy-1-alkanol derivatives were selectively converted to the corresponding C-3 opening products. Both strong solid bases (MgO, CaO, and hydroxyapatite) and strong solid acids (Al 3+-and Fe 3+-exchanged montmorillonites) catalyzed the cyanosilylation of carbonyl compounds with Me 3SiCN regioselectively. On CaO, α,β-unsaturated ketones were cyanosilylated to give the 1,2-adducts selectively, while the solid acids gave the 1,4-adducts selectively. Hydrosilylation of carbonyl compounds with hydrosilanes was also efficiently catalyzed by solid acids and bases. Enones are selectively hydrosilylated over hydroxyapatite to afford the corresponding 1,2-adducts in high yields. Thus the solid acids and bases appear to be highly pertinent as catalysts to the activation of carbonyl compounds or epoxides and organosilane nucleophiles, respectively.

ChemInform Abstract: Highly Regio‐ and Chemoselective Ring Opening of Epoxides with Trimethylsilyl Azide in the Presence of Aluminum Isopropoxide and Titanium Isopropoxide.

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.

Regiospecific Ring Opening of Epoxides with Cyanotrimethylsilane on Solid Bases: Reaction Features, and Role of Metal Cations of Solid Bases

Abstract A new attempt of utilizing solid acids and bases for ring opening of epoxides with Me3SiCN was investigated. Solid strong bases such as calcium oxide and magnesium oxide catalyzed the regio- and chemoselective ring opening of epoxides with Me3SiCN much more effectively than homogeneous catalysts. On CaO and MgO, the reactions of unsymmetrical epoxides with Me3SiCN afforded 3-trimethylsiloxyalkanenitriles in high yields through regio- and stereoselective attack of cyanide ion on the less substituted epoxycarbon. Additionally, on CaO, 2,3-epoxy-1-alkanol derivatives were selectively converted to the corresponding C-3 opened products by the attack of cyanide ion. In these cases no isocyanides were formed. It was suggested that CaO acted as a bifunctional catalyst; the lattice oxide anions of CaO activated Me3SiCN, and simultaneously calcium ions promoted the ring opening of epoxyalkanol as Lewis acid sites.

Highly regio and chemoselective ring opening of epoxides with trimethylsilyl azide in the presence of aluminium isopropoxide and titanium isopropoxide

The ring-opening of functionalized epoxides with trimethylsilyl azide in the presence of a catalytic amount of Ti(O- i-Pr) 4 or Al(O- i-Pr) 3 is described. The reaction is stereospecific and highly regiospecific, leading generally to the formation of the carbon-azido bond on the less substituted carbon. The mechanism of this reaction is also discussed.

Regio- and Chemoselective Ring Opening of Epoxides to Bromohydrins with Dilithium Tetrabromocuprate

Dilithium tetrabromocuprate, prepared from lithium bromide and copper(II) bromide, regioselectively converts functionalized epoxides (11 examples) to vicinal bromohydrins resulting from nucleophilic attack by bromide at the less substituted epoxide carbon.

ChemInform Abstract: Synthetic Methods and Reactions. Part 144. Regiospecific and Chemoselective Ring Opening of Epoxides (I) with Trimethylsilyl Cyanide (II) ‐Potassium Cyanide/18‐Crown‐6 Complex.

ChemInformVolume 21, Issue 36 Isocyclic Compounds ChemInform Abstract: Synthetic Methods and Reactions. Part 144. Regiospecific and Chemoselective Ring Opening of Epoxides (I) with Trimethylsilyl Cyanide (II) -Potassium Cyanide/18-Crown-6 Complex. M. B. SASSAMAN, M. B. SASSAMAN Loker Hydrocarbon Res. Inst., Dep. Chem., Univ. South. Calif., Los Angeles, CA 90089, USASearch for more papers by this authorG. K. S. PRAKASH, G. K. S. PRAKASH Loker Hydrocarbon Res. Inst., Dep. Chem., Univ. South. Calif., Los Angeles, CA 90089, USASearch for more papers by this authorG. A. OLAH, G. A. OLAH Loker Hydrocarbon Res. Inst., Dep. Chem., Univ. South. Calif., Los Angeles, CA 90089, USASearch for more papers by this author M. B. SASSAMAN, M. B. SASSAMAN Loker Hydrocarbon Res. Inst., Dep. Chem., Univ. South. Calif., Los Angeles, CA 90089, USASearch for more papers by this authorG. K. S. PRAKASH, G. K. S. PRAKASH Loker Hydrocarbon Res. Inst., Dep. Chem., Univ. South. Calif., Los Angeles, CA 90089, USASearch for more papers by this authorG. A. OLAH, G. A. OLAH Loker Hydrocarbon Res. Inst., Dep. Chem., Univ. South. Calif., Los Angeles, CA 90089, USASearch for more papers by this author First published: September 4, 1990 https://doi.org/10.1002/chin.199036128AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue36September 4, 1990 RelatedInformation

Synthetic methods and reactions. 144. Regiospecific and chemoselective ring opening of epoxides with trimethylsilyl cyanide-potassium cyanide/18-crown-6 complex

Trimethylsilyl cyanide with catalytic potassium cyanide/18-crown-6 complex opens epoxides regiospecifically to give 3-((trimethylsilyl)oxy) nitriles. The addition of cyanide occurs at the least substituted carbon. The reaction is chemoselective for monosubstituted epoxides due the participation of a pentavalent silicon species

A novel reaction for the functionalization of epoxy resins: New regio- and chemoselective ring-opening of epoxides with aryl silyl ether catalyzed by cesium fluoride

By use of cesium fluoride as a catalyst, aryl or alkyl glycidyl ethers were ring-opened by aryl trimethylsilyl ether to produce O-protected aryloxyhydrins with a quantitative regioselectivity for the first time. Alkyl silyl ether was ineffective for this ring-opening.

ChemInform Abstract: A Highly Regio‐ and Chemoselective Ring Opening of Epoxides (I) with Trimethylsilyl Azide (II)/Aluminum Isopropoxide.

ChemInform Abstract: A Highly Regio‐ and Chemoselective Ring Opening of Epoxides (I) with Trimethylsilyl Azide (II)/Aluminum Isopropoxide.

A Highly Regio- and Chemoselective Ring Opening of Epoxides with Trimethylsilyl Azide/Aluminum Isopropoxide

Functionalized epoxides are regioselectively opened using trimethylsilyl azide/aluminum isopropoxide giving 2-trimethylsiloxy azides by attack on the less substituted carbon.