Showing papers in "Tetrahedron Letters in 2007"

TL;DR: Diammonium hydrogen phosphate, (NH 4 ) 2 HPO 4 (DAHP), efficiently catalyzes the one-pot, three-component reaction of an aromatic aldehyde, malononitrile and 4-hydroxycoumarin in aqueous media under mild conditions at room temperature, to afford the corresponding dihydropyrano[ c ]chromenes in high yields as discussed by the authors.

TL;DR: A new one-pot procedure was developed to synthesize 1-aryl- and 1-vinyl-1,2,3-triazoles directly from boronic acids and alkynes, which avoided the need to isolate unstable azide intermediates.

TL;DR: In this paper, a new rhodamine derivatives bearing urea group have been synthesized for the detection of metal ions, and the dimeric system 2 displayed a selective fluorescent enhancement and colorimetric change upon the addition of Hg 2+, in which the spirolactam (nonfluorescent) to ring opened amide process was utilized.

TL;DR: A novel compound FD1 was demonstrated as a turn-on fluorescent sensor for imaging of iron(III) ion in biological samples that exhibited high selectivity and sensitivity for Fe 3+ over other metal ions.

TL;DR: In this article, a mechanistic study of [3+2] cycloaddition of allenoate and acrylate is presented, showing that the involvement of a molecule of water, which services as a proton-shuttle, is essential for annulated product formation.

TL;DR: A new method for the preparation of peptide thioester by the post-solid phase peptide synthesis (SPPS) approach was developed and a series of N -alkyl cysteine derivatives were prepared and used as the C-terminus residue of the peptides prepared by the Fmoc SPPS.

TL;DR: In this article, a new room temperature ionic liquid (IL) (2-hydroxyethyl)-trimethyl-ammonium (S)-2-pyrrolidinecarboxylic acid salt ([Choline][Pro]) has been synthesized from biorenewable and nontoxic raw materials (choline chloride and l (−)-proline) in a simple and relative green route.

TL;DR: Aminolysis of esters by using the organocatalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) is reported as mentioned in this paper.

TL;DR: In this paper, an operationally trivial and environmentally benign procedure for direct Michael addition has been developed, where the reaction of various ketones with nitroolefins can be performed in water to afford the corresponding nitro compounds in high yields in the presence of a pyrrolidine-thiourea organocatalyst at 35°C.

TL;DR: In this paper, a Pd-catalyzed synthesis of (hetero)aromatic nitriles from the corresponding aryl chlorides and potassium hexacyanoferrate(II) is described.

TL;DR: The addition of amines to conjugated alkenes has been carried out in water at room temperature very efficiently without any catalyst as mentioned in this paper, and significant rate acceleration of this reaction is observed in water compared to organic solvents.

TL;DR: In this article, a two-channel metal ion sensor has been synthesized from macrocyclic dioxotetraamine and 1,8-naphthalimide derivative, which can be used for the visual and spectroscopic detection of Cu2+ or Hg2+ in the presence of the other competing metal ions.

TL;DR: Polystyrene-supported proline has been used as organocatalyst in the asymmetric aldol reaction between cyclohexanone and substituted benzaldehydes in water without any additive as mentioned in this paper.

TL;DR: In this article, a new rhodamine-based fluorescent chemosensor for transition metal cations was synthesized by one-step facile condensation of Rhodamine B and 2-aminopyridine.

TL;DR: In this article, the Ullmann reaction was performed in the presence of a 3-(2-aminoethylamino)propyl functionalized silica gel immobilized copper catalyst.

TL;DR: In this paper, the synthesis of substituted acetophenones (2a-12a) with various aromatic aldehydes (1b-7b) in the presence of BF3-Et2O at room temperature gave chalcones in 75% yield.

TL;DR: Two closely structurally related coumarins, 4-hydroxy-8-isopropyl-5-methylcoumarin and 4-Hydroxy-6-chloro-7-methyl coumarin, were acylated at C-3 and further converted to the respective chalcones and two series of eighteen new compounds, which were evaluated for possible antiviral activity as discussed by the authors.

TL;DR: The thiourea and urea functionalised 4-amino-1,8-naphthalimide sensors were synthesized in high yield in three steps as mentioned in this paper.

TL;DR: In this paper, the diastereoselective pot, atom and step economic (PASE) synthesis of highly functionalized piperidines has been realized, which simply involves mixing methyl acetoacetate, 2 equiv of aldehyde and 2 equaliv of aniline together in the presence of InCl3.

TL;DR: In this article, a method for the synthesis of quinoxalines and dihydropyrazines (DHPs) using α-bromo ketones and 1,2-diamines in the presence of silica supported perchloric acid (HClO4·SiO2) at room temperature was developed.

TL;DR: In this article, a modification using sulfuric acid immobilized on silica as catalyst for the preparation of glycosides from free sugars such as d-glucose, d-galactose and d-mannose was presented.

TL;DR: In this article, an exceptionally mild, general and efficient copper catalyzed cross coupling reaction of aryl bromides and thiols using 0.5 ǫ% CuI and 1 mµ% benzotriazole was reported.

TL;DR: In this article, the synthesis of 2-aryl-1-arylmethyl-1 H -benzimidazoles from a wide range of substituted o -phenylenediamines and aldehydes under mild conditions using chloroform as a solvent at ambient temperature.

TL;DR: The reactions of benzoic acid derivatives with (N-isocyanimino)triphenylphosphorane proceed smoothly at room temperature to afford 2-aryl-1,3,4-oxadiazoles in high yields as mentioned in this paper.

TL;DR: In this paper, the use of zinc chloride to catalyze the one-pot, three component synthesis of imidazo[1,2-a ]pyridines from a range of substrates using either conventional heating or microwave irradiation is described.

TL;DR: An inexpensive and readily available catalyst, Zn(OAc) 2 ·2H 2 O, was successfully evaluated for effective one-pot synthesis of propargylamines with moderate to excellent yields for most of the substrates screened, without the need of base, co-catalyst or additive in the presence of air as discussed by the authors.

TL;DR: In this article, the FeCl 3 -catalyzed C3-selective Friedel-Crafts alkylation of indoles using allylic, benzylic and propargylic alcohols has been developed.

TL;DR: A hydroxamate-based chemosensor, which responds fluorescently and colorimetrically to FeIII in micromolar ranges, has been developed.

TL;DR: In this article, a series of imines was synthesized by an ultrasound assisted reaction of aldehydes and primary amines using silica as the promoter, and products were obtained in high yields even in large scale synthesis.

TL;DR: In this article, a three-component Mannich-type reaction of acetophenone, aromatic aldehydes and aromatic amines was catalyzed by NbCl5 at ambient temperature to give various P-amino ketones in high yields.