Showing papers in "Tetrahedron Letters in 2003"

TL;DR: Silica sulfuric acid as discussed by the authors can be used to catalyse the Biginelli reaction between an aldehyde, a β-dicarbonyl compound and urea or thiourea in refluxing ethanol.

TL;DR: Copper(II) triflate catalyzes efficiently the three-component condensation reaction of an aldehyde, β-ketoester and urea in acetonitrile to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones in high yields as mentioned in this paper.

TL;DR: Highly rapid and efficient electrophilic substitution reactions of indoles with various aldehydes and ketones were carried out using I2 in CH3CN to afford the corresponding bis(indolyl)methanes in excellent yields.

TL;DR: In this article, a direct catalytic enantioselective α-aminooxylation of aldehydes was developed using nitrosobenzene as the oxygen source and l -proline as the catalyst.

TL;DR: In this paper, the synthesis of substituted Hantzsch 1,4-dihydropyridines has been achieved using the classical hantzsch procedure and modified Hantzch conditions for the first time at room temperature in the presence of iodotrimethylsilane (TMSI) generated in situ in CH3CN, in excellent yields.

TL;DR: The 4-amino-1,8-naphthalimide-based chemosensors 2, 4 and 6 showed striking green-to-purple colour changes due to the deprotonation of the 4amino moiety on interaction with strongly basic anions such as F−: these colour changes reverse gradually with time due to fixation of atmospheric CO2 (as HCO3−) yielding 1:1 adducts as demonstrated by X-ray crystallography as discussed by the authors.

TL;DR: In this article, a new catalytic system consisting of [Cp*IrCl2]2/K2CO3 (Cp *=pentamethylcyclopentadienyl) for the N-alkylation of primary amines with alcohols has been developed.

TL;DR: In this article, the design and synthesis of two novel fluorescent PET anion sensors is described, based on the principle of "fluorophore-spacer-(anion)receptor"

TL;DR: In this article, the synthesis of cyclic carbonates by CO2 insertion into epoxides catalysed by both homogeneous MTBD and TDB supported on MCM-41 mesoporous silica is reported.

TL;DR: In this article, tetrasubstituted pyrazole derivatives were synthesized regioselectively in good yields from the reaction of Baylis-Hillman adducts 1a- f and hydrazine hydrochlorides 2a- d in 1,2-dichloroethane.

TL;DR: Ammonium chloride as a very inexpensive and readily available reagent, and efficiently catalyzes one-pot, three component, Biginelli condensation reactions of aldehydes, 1,3-dicarbonyl compounds and urea or thiourea under solvent-free conditions to afford the corresponding 3,4-dihydropyrimidin-2-(1H)-ones in high yields at 100°C.

TL;DR: LiBr catalyses efficiently the three component condensation reaction of an aldehyde, a β-ketoester and urea in refluxing acetonitrile to afford the corresponding dihydropyrimidinones in high yield.

TL;DR: In this article, a reductive cyclization of o-nitrobenzamides and triethyl orthoformate, aldehydes or ketones promoted by TiCl4/Zn was proposed.

TL;DR: In this article, 2-Amino-, and 2-alkyl-benzothiazoles have been efficiently prepared by palladium catalyzed cyclization of o -bromophenylthioureas and o-bromphenylthiamides.

TL;DR: In this article, a 4-alkylcoumarin-3-carboxylic acid was obtained in high yields with excellent purity from ortho-hydroxybenzaldehydes and Meldrum's acid after a 2 h reflux in ethanol.

TL;DR: In this paper, the authors showed that aromatic amines exhibit excellent regioselectivity for preferential nucleophilic attack at the sterically less hindered position during the reaction with unsymmetrical epoxides.

TL;DR: In this paper, a smooth ring-opening with aryl amines in 1-butyl-3-methylimidazolium tetrafluoroborate (BF4) or 1-(butyl)-methylamine hexafluorophosphate (PF6) ionic liquids under mild and neutral conditions to afford β-amino alcohols in excellent yields with high regioselectivity.

TL;DR: In this article, a simple effective synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives, using boric acid as catalyst, from aromatic aldehydes, 1,3-dicarbonyl compounds and urea in glacial acetic acid is described.

TL;DR: In this paper, the three component condensation of an aldehyde, a β-keto ester and urea (thiourea) in the presence of a catalytic amount of VCl 3 is disclosed for the solution phase synthesis of dihydropyrimidinones.

TL;DR: The mildest method of N-vinylation has been discovered as discussed by the authors, and the synthetic utilities of the N- and Ovinylated products include protecting group, cyclopropanation and Grubbs' ring closure metathesis reactions.

TL;DR: The reaction of o-phenylenediamines with both acyclic and cyclic ketones in the ionic liquid 1,3-di-n-butylimidazolium bromide afforded 1,5-benzodiazepines in excellent isolated yields in the absence of a catalyst at ambient temperature as discussed by the authors.

TL;DR: Microwave-assisted three-component cyclocondensation of barbituric acids, benzaldehyde and alkyl nitriles was shown to yield pyrano[2,3-d]pyrimidines.

TL;DR: In this paper, an unusual α-galactosylation using phenylthioglycoside of 4,6-O-di-tert-butylsilylene (DTBS)-protected galactose derivatives as a glycosyl donor was discovered.

TL;DR: In this article, a plausible reaction mechanism involving in situ generation of arylphosphites from phenols and hexamethylphosphorous triamide (HMPT) was proposed.

TL;DR: In this paper, the selective oxidative conversion of a variety of highly functionalized 1°, 2°-1,5-diols into the corresponding δ-lactones has been effected simply and efficiently using a reagent system comprised of catalytic 2,2,6, 6,6-tetrmethylpiperidinooxy (TEMPO) and excess bis-acetoxyiodobenzene (BAIB).

TL;DR: In this article, a facile route to benzoxazoles was developed using microwave-assisted dielectric heating, and the ease of synthesis and workup allowed the parallel synthesis of a 48-membered library of benzoxide quickly and efficiently.

TL;DR: In this paper, the first successful cross-coupling of a heterocyclic boronate with heteroarenes, such as indazole, has been demonstrated.

TL;DR: In this paper, a simple and efficient procedure for chlorination and bromination of aromatic amines, hydrocarbons and naphthols by the action of aqueous hydrohalic acid and hydrogen peroxide is described.

TL;DR: The one-pot, three-component condensation of benzil, benzonitrile derivatives and primary amines on the surface of silica gel under solvent-free conditions and microwave irradiation provided tetrasubstituted imidazoles in high yields.

TL;DR: In this article, Bacillamide (1 ) was isolated as a new algicide against the harmful dinoflagellate, Cochlodinium polykrikoides, from the marine bacterium, Bacillus sp. SY-1.