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Showing papers in "Tetrahedron Letters in 2004"


Journal ArticleDOI
TL;DR: Condensation of anthranilamide with aryl, alkyl or heteroaryl aldehydes in refluxing ethanol and the presence of CuCl2 afforded the corresponding 2-substituted quinazolinones in excellent yields as mentioned in this paper.

229 citations


Journal ArticleDOI
TL;DR: CoTPP(Cl)/DMAP was found to be a highly active catalyst system for the chemical fixation of CO 2 via reaction with epoxides as mentioned in this paper, and corresponding cyclic carbonate products were produced in high yield and selectivity for a variety of terminal mono and disubstituted epoxide.

228 citations


Journal ArticleDOI
TL;DR: A chiral bis-thiourea-type organocatalyst 2 developed for the Baylis-Hillman reaction provided a drastic rate enhancement in the case of cyclohexanecarboxaldehyde as discussed by the authors.

212 citations


Journal ArticleDOI
TL;DR: Sodium bromide catalysed three-component cyclocondensation of aryl aldehydes, alkyl nitriles and dimedone proceeds under microwave irradiation in solvent free conditions to give highly functionalised tetrahydrobenzo[b]pyrans in excellent yields as discussed by the authors.

211 citations


Journal ArticleDOI
TL;DR: In this article, functionalized quinoxalines and heterocyclic pyrazines are expediently prepared in excellent yields (69-99%) from common 1,2-diketone intermediates under microwave irradiation.

200 citations


Journal ArticleDOI
TL;DR: In this article, ω-(o-Alkylphenyl)alkanoic acids with 16, 18 and 20 carbon atoms were identified in archaeological pottery vessels from coastal sites in Southern Brazil.

185 citations


Journal ArticleDOI
TL;DR: In this paper, an efficient catalytic system for the reactions of indole with aldehydes/ketones or imines was presented, where the use of ionic liquids as the reaction media allows facile separation and recycling of the catalyst.

179 citations


Journal ArticleDOI
TL;DR: In this paper, the ZnCl2/[BMIm]Br catalyst was used for the chemical fixation of CO2 with mono-substituted terminal epoxides or cyclohexene oxide to form cyclic carbonates.

177 citations


Journal ArticleDOI
TL;DR: In this article, the first example of the use of chiral ionic liquids as reaction media in the asymmetric Baylis-Hillman reaction was described using N -alkyl- N -methylephedrinium salts.

162 citations


Journal ArticleDOI
TL;DR: The technique was demonstrated here for the case of the amyloid peptide Aβ(1–42), where the first Ser residue was used to incorporate a depsipeptide unit and the resulting hybrid was readily assembled.

162 citations


Journal ArticleDOI
TL;DR: A three-component coupling of aldehyde, alkyne, and amine was developed by using gold, copper, or silver as catalysts in ionic liquid as discussed by the authors.

Journal ArticleDOI
TL;DR: Grindstone Chemistry as mentioned in this paper is a greatly evolved version of Toda's method of grinding solids together for solvent-free chemical reactions and its usefulness is illustrated by the successful application of this technique to a simplified process for conducting the multi-component Biginelli reaction for the synthesis of physiologically active tetrahydropyrimidinones.

Journal ArticleDOI
TL;DR: In this article, a simple protocol for the 1,3-dipolar cycloaddition of azides with electron-deficient alkynes was reported, which is a potential method for introducing functional groups to DNA under biological conditions.

Journal ArticleDOI
TL;DR: In this paper, a 12H-benzo[a]xanthenes from 2-tetralone and 2-hydroxyaromatic aldehydes is described.

Journal ArticleDOI
TL;DR: In this article, the asymmetric synthesis of 4-nitrocyclohexanone derivatives has been accomplished by enantioselective double Michael additions of γ, δ-unsaturated β-ketoesters to nitroalkenes using a catalytic amount of bifunctional thiourea and TMG.

Journal ArticleDOI
TL;DR: 2-Halo-anilines, protected as the corresponding sulfonamides or carbamates, can be converted very efficiently into 3-iodoindoles by sequential Sonogashira coupling with a 1-alkyne and 5-endo-dig iodocyclisation.

Journal ArticleDOI
TL;DR: Iodine was found to promote quantitative acetylation of alcohols in a very short time with an equimolar amount of acetic anhydride under solvent-free conditions at room temperature as mentioned in this paper.

Journal ArticleDOI
TL;DR: Bismuth triflate catalyzes the ring opening of epoxides with aromatic amines under aqueous conditions and affords the corresponding β-amino alcohols in excellent yields as mentioned in this paper.

Journal ArticleDOI
TL;DR: Magnesium perchlorate has been found to be an efficient catalyst for the synthesis of imines and phenylhydrazones by the reaction of carbonyl compounds with amines as discussed by the authors.

Journal ArticleDOI
TL;DR: In this article, 2-amino-2-chromenes were obtained in excellent yield and selectivity simply by mixing malononitrile, α-naphthol and aromatic aldehydes in water in the presence of basic alumina as heterogeneous and reusable catalyst.

Journal ArticleDOI
TL;DR: In this article, a highly general, experimentally simple, and inexpensive catalyst system was developed for the amidation of aryl iodides by using 5 Âmol Â% of CuI as catalyst, 20 Âm of an amino acid as ligand, and K3PO4 as base.

Journal ArticleDOI
TL;DR: A polymer-supported N-heterocyclic carbene (NHC) was prepared from chloromethyl polystyrene (CM PS) resin using a simple procedure, and was used as the ligand for palladium catalysts as discussed by the authors.

Journal ArticleDOI
TL;DR: Pyrrolo-dC (1a, 6-methyl-3-(2-deoxy-β-d -ribofuranosyl)-3 H -pyrrolO[2,3-d ]pyrimidin-2-one) and its cyanoethyl phosphoramidite 2a were synthesized and incorporated into oligodeoxyribonucleotides by standard automated synthesis techniques as mentioned in this paper.

Journal ArticleDOI
TL;DR: A facile synthesis of fused dihydrotriazolo[1,5-a]pyrazinones and triazolobenzodiazepines by an Ugi/alkyne–azide cycloaddition synthetic sequence is reported.

Journal ArticleDOI
TL;DR: In this article, a fluorogenic chemosensing system was described and shown to selectively detect pyrophosphate under physiological conditions, in which pyrophophosphate and hydrogen phosphate were capable of displacing a fluorescent coumarin-derived indicator from a bis Zn 2+ -dipicolylamine coordination compound.

Journal ArticleDOI
TL;DR: In this paper, a proline-catalyzed direct asymmetric cross-aldol reaction with aldehydes was performed in ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate media, which simplified product isolation and catalyst recycling.

Journal ArticleDOI
Bo Wang1, Yanlong Gu1, Cheng Luo1, Tao Yang1, Liming Yang1, Jishuan Suo1 
TL;DR: Sulfamic acid (H 2 NSO 3 H) has been proved to be an efficient and green catalyst for liquid Beckmann rearrangement of ketoxime in dried acetonitrile as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, the coupling of three components, namely an aldehyde, an alkyne and an amine to prepare propargylamines was performed using copper exchanged hydroxyapatite (CuHAP) as the catalyst under mild reaction conditions and in the absence of any co-catalyst.

Journal ArticleDOI
TL;DR: It has been shown that catalytic amounts of bis-aryl (thio)ureas greatly accelerate the DABCO-promoted Baylis–Hillman reaction between a range of aromatic aldehydes and methyl acrylate in the absence of solvent.

Journal ArticleDOI
TL;DR: A simple and efficient one-pot method for α-aminonitriles from aldehydes, amines, and trimethylsilyl cyanide in the presence of a catalytic amount of bismuth trichloride was developed in this paper.