Carbon Nucleophiles (carbon + nucleophile)

Distribution by Scientific Domains


Selected Abstracts


Gold(I) Catalysis: Selective Synthesis of Six- or Seven-Membered Heterocycles from Epoxy Alkynes

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2009
Lun-Zhi Dai
Abstract Gold(I)-catalyzed intramolecular cycloisomerization of ketone-substituted epoxides with alkynes to six- or seven-membered heterocyclic compounds is firstly introduced in this paper. This procedure involves a cascade isomerization of the ketone-substituted epoxides into 1,3-diketones in the presence of a Lewis acid and subsequent gold(I)-catalyzed selective intramolecular addition of an oxygen or a carbon nucleophile to the alkynes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


An Efficient and General Microwave-Assisted Copper-Catalyzed Conia-Ene Reaction of Terminal and Internal Alkynes Tethered to a Wide Variety of Carbonucleophiles

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2010
Sonia Montel
Abstract This paper describes a highly efficient, microwave-assisted, Conia-ene reaction of alkynes bearing a stabilizing carbon nucleophile. The reaction, catalyzed by a commercially available copper catalyst, proceeds under neutral conditions and is generally applicable even to less reactive nucleophiles such as malonate, cyanoacetate, and sulfonylacetate derivatives. This copper-mediated cycloisomerization is also applicable to internal unactivated alkynes leading exclusively to the corresponding 5-membererd products having an E -olefinic chemistry. [source]


An Efficient Molybdenum(VI)-Catalyzed Direct Substitution of Allylic Alcohols with Nitrogen, Oxygen, and Carbon Nucleophiles

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 5 2009
Hongwei Yang
Abstract Direct nucleophilic substitution of allylic alcohols with various nitrogen, oxygen, and carbon nucleophiles catalyzed by MoO2(acac)2 was realized. The corresponding products were obtained in moderate-to-excellent yields. Studies of the reaction mechanism showed that a carbenium intermediate was formed in the transition state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


Facile Access to Optically Active Ferrocenyl Derivatives with Direct Substitution of the Hydroxy Group Catalyzed by Indium Tribromide

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2007
Paola Vicennati
Abstract Ferrocene derivatives have found many different uses and applications in organometallic chemistry, material chemistry, and catalysis. We have shown that using a catalytic amount (5,10 mol-%) of commercially available indium tribromide, at room temperature, many carbon nucleophiles, such as indoles, allylsilane, enolsilane, silyl ketene acetal, diketone, and trimethylsilylcyanide, smoothly react with different optically active ferrocenyl alcohol derivatives to afford the desired products in high yield, with retention of configuration. Also, many different N-nucleophiles (azide, carbamates) and O-nucleophiles (alcohols) react as well, again with retention of configuration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]


Stereoselective Synthesis of C- and N-Ketosides by Lewis Acid-Catalyzed C- and N-Glycosidation of Alkynyl, Phenyl, and Methyl Ketoses

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2003
Ana M. Gómez
Abstract C-Ketosides can be prepared conveniently, in a stereoselective manner, from alkynyl, phenyl and methyl glucopyranose hemiketals by reaction with carbon nucleophiles in the presence of Lewis acids. The reaction of the hemiketals with trimethylsilyl azide provides an efficient route to the corresponding N-ketopyranosides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]


5-Chloro-3-methylthio-1,2,4-thiadiazol-2-ium chlorides as useful synthetic precursors to a variety of 6a,4 -thiapentalene systems

HETEROATOM CHEMISTRY, Issue 1 2003
Georges Morel
Title salts 3 were easily obtained by treatment of formimidoyl isothiocyanates 1 with a twofold excess of methanesulfenyl chloride. They showed interesting chemical behavior toward several nitrogen and carbon nucleophiles. Substitution reactions with isothioureas and acetamide in the presence of triethylamine gave the 1H, 6H -6a,4 -thia-1,3,4,6-tetraazapentalenes 7 and 6H -6a,4 -thia-1-oxa-3,4,6-triazapentalene 9, respectively. Addition of p -toluidine furnished the 5-imino-thiadiazole derivatives 10, which reacted further with diverse heterocumulenes to yield the corresponding thiatriaza- and tetraazapentalene species 11. The N,N,-bis(1,2,4-thiadiazol-5-ylidene)diaminobenzenes 13 were also prepared and reacted with phenyl isothiocyanate. Two stable rotational isomers were separated for the 1,2-phenylene product 14b. Other ,-hypervalent sulfur compounds 16 were synthesized under similar conditions from salts 3 and methyl cyanoacetate or dimethyl malonate. The structural assignments were discussed on the basis of IR and NMR spectroscopic data and received additional support from X-ray analysis of substrate 16a. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:95,105, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10106 [source]


The nitro anomaly and Brønsted ,nuc values in SN2 reactions on chlorine,

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2002
Linoam Eliad
Abstract The kinetics of chlorine transfer reactions between N -chlorosuccinimide (NCS) and four carbon nucleophiles (the conjugated bases of phenyldinitromethane, Meldrum's acid, phenylmalononitrile and phenylnitro-methane) in water were determined. A plot of log k for the SN2 reactions vs the pKa of the first three conjugated acids of the nucleophiles gave a straight line with a slope (,nuc) of 1.8. The data point for the mononitro derivative, phenylnitromethane, deviates negatively from the line by 6.7 log units. This deviation is typical of proton transfer reactions and was recently shown to occur also in SN2 reactions on bromine. Copyright © 2002 John Wiley & Sons, Ltd. [source]


Byproduct-Catalyzed Four-Component Reactions of Aldehydes with Hexamethyldisilazane, Chloroformates, and Nucleophiles in Acetonitrile Leading to Protected Primary Amines, ,-Amino Esters, and ,-Amino Ketones

CHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2010
Bai-Ling Yang
Abstract Multicomponent reactions are a very powerful tool for the construction of complex organic molecules by using readily available starting materials. While most of the multicomponent reactions discovered so far consist of three components, the reactions with four or more components remain sparse. We have successfully developed several four-component reactions using a catalytic amount of water as a hydrolyzing agent to decompose byproduct chlorotrimethylsilane (TMSCl) to yield secondary byproduct HCl that serves as a catalyst. In the presence of 40,mol,% of water, the four-component reaction of aldehydes with hexamethyldisilazane (HMDS), chloroformates, and silylated nucleophiles proceeds smoothly at room temperature to give a range of protected primary amines in moderate to excellent yields. Importantly, a wide variety of protic carbon nucleophiles, such as ,-keto esters, ,-diketones, and ketones, have further been explored as suitable substrates for the synthesis of protected ,-amino esters and ,-amino ketones that are useful building blocks for various pharmaceuticals and natural products. These four-component reactions proceed through a pathway of tandem nitrogen protection/imine formation/imine addition, and the decomposition of byproduct TMSCl, generated in the first step of nitrogen protection, with water results in the formation of secondary byproduct HCl, a strong Brønsted acid that catalyzes the following imine formation/imine addition. Taking advantage of the fact that alcohols or phenols are also able to decompose byproduct TMSCl to yield secondary byproduct HCl, no catalyst is needed at all for the four-component reactions with aldehydes bearing hydroxy groups. [source]