Showing papers in "Tetrahedron Letters in 2001"

TL;DR: In this article, 3,4-Dihydropyrimidin-2(1 H )-ones were synthesized in high yields by one-pot three-component Biginelli condensation in the presence of room temperature ionic liquids such as 1- n -butyl-3-methylimidazolium tetrafluoroborate (BMImBF 4 ) or hexafluorophosphorate ( BMImPF 6 ) as catalysts under solvent-free and neutral conditions.

TL;DR: In this paper, general catalytic Cu(OAc)2/TEMPO systems for the CN and CO cross-coupling reactions with arylboronic acid have been discovered.

TL;DR: Glycosyl (N-phenyl)trifluoroacetimidates, readily prepared from 1-hydroxyl sugars by treatment with (N)-phenyl trifluoracetimidoyl chloride in the presence of K2CO3, were demonstrated to be effective glycosyl donors as mentioned in this paper.

TL;DR: In this article, a protocol for the synthesis of functionalized diaryl- and triarylamines under mild conditions, using a soluble, air-stable copper(I) complex, Cu(PPh3)3Br, as the catalyst and cesium carbonate as the base, was presented.

TL;DR: In this paper, the enantioselective direct Michael addition of ketones using (S )-1-(2-pyrrolidinylmethyl)-pyrrinidine as a catalyst is described.

TL;DR: In this article, Butyl-3methylimidazolium chloroaluminate, (bmim)Cl·2AlCl3 ionic liquid is used as an alternative to conventional acid catalysts in the Pechmann condensation of phenols with ethyl acetoacetate leading to the formation of coumarin derivatives.

TL;DR: TaCl5−SiO2 has been used as an efficient Lewis acid catalyst for the three component coupling of carbonyl compounds, aromatic amines and diethyl phosphite to produce α-amino phosphonates as discussed by the authors.

TL;DR: In this article, a simple and efficient oxidation of alcohols to carbonyl compounds by oxygen at room temperature is described; it requires the laccase/TEMPO mediator system as the catalyst.

TL;DR: In this paper, three chiral cyclic secondary amines were shown to be catalysts for the direct asymmetric Mannich-type reaction of acetone with a variety of preformed aldimines derived from o-anisidine.

TL;DR: In this paper, 2,3-Dihydro-1 H -1,5 benzodiazepines have been synthetized in very good yield in solvent-free conditions from o -phenylendiamine and ketones in the presence of Yb(OTf) 3 as catalyst.

TL;DR: In this article, the amination reaction features low (0.5 mol%) catalyst loading, mild reaction temperature (80°C) and low reaction pressure (50 psi), and is further studied in amination of a variety of aryl halides.

TL;DR: Magnesium oxide/phosphorus oxychloride (MOPO) was found to be an efficient reagent for the preparation of 1,5-benzodiazepine derivatives of o -phenylenediamine and ketones as discussed by the authors.

TL;DR: The reaction of the internal alkyne with alcohols 2 in the presence of a catalytic amount of Pd(PPh3)4 and benzoic acid in dioxane at 100°C gave the allylic ethers 3 in good to high yields as discussed by the authors.

TL;DR: In this article, the catalytic enantioselective Michael reaction promoted by quaternary ammonium salt from cinchonidine as a phase-transfer catalyst was described, and the treatment of malonate with chalcone derivatives under mild reaction conditions afforded the corresponding Michael adducts in good yields with good to moderate enantiomeric excesses.

TL;DR: In this paper, an efficient synthesis of 3,4-dihydropyrimidin-2-(1H)-ones using solid-supported ytterbium(III) reagent from aldehydes, 1,3-dicarbonyl compounds and urea (Biginelli reaction) under solvent-free conditions is described.

TL;DR: In this paper, a catalytic amount of Mn(II)-Co(II) or Mn(III)-Cu(III) nitrates in combination with TEMPO allows the selective oxidation of primary and secondary alcohols to aldehydes and ketones by oxygen under very mild conditions.

TL;DR: In this article, Tetracoordinate hydronium organotrifluoroborate (THO) was used to generate tetra-n -butylammonium hydroxide.

TL;DR: In this paper, the preparation and applications in the Knoevenagel and 1,3-dipolar cycloaddition reactions of new grafted soluble liquid phases derived from imidazolium ionic liquids are described.

TL;DR: In this paper, the transition metal-mediated cyclization of aromatic enynes provides high yields of substituted naphthalene compounds, and the most useful catalysts were found to be [Rh(CO) 2 Cl] 2, PdCl 2 and PtCl 2.

TL;DR: In this paper, a 1-phenyl-2-mercaptoethyl auxiliary moiety on the α-amino group of a first peptide segment was used to effect thioester-mediated, amide-forming ligation with a second peptide.

TL;DR: In this article, it was shown that iron(III) corroles were more selective catalysts than analogous porphyrins for the aziridination of olefins by PhINTs, and, most important, the iron(IV) corrole displays the unique ability of utilizing Chloramine-T as nitrogen atom source.

TL;DR: In this article, N, N ′-bis(p -nitrophenyl)thiourea as a hydrogen-bonding chromoionophore in 1% water and 99% MeCN (v/v) was successfully determined by the complexation-induced chromogenic response.

TL;DR: In this paper, the oxidations of organic compounds by permanganate under solvent free conditions have been studied and the experimental procedure is simple and the products are easily isolated in good yields.

TL;DR: In this article, a simple, efficient and general method was developed for the synthesis of 1-aminoalkyl phosphonates through a one-pot reaction of aldehydes with amines in the presence of acidic alumina under solvent-free conditions using microwave irradiation.

TL;DR: Tetrabutylammonium fluoride (TBAF) was found to be a mild and efficient catalyst for the synthesis of 3,5-disubstituted-1,2,4-oxadiazoles as discussed by the authors.

TL;DR: In this paper, the authors performed Beckmann rearrangements of several ketoximes in the catalytic media consisting of room temperature ionic liquid based on 1,3-dialkylimidazolium or alkylpyridinium salts and phosphorated compounds.

TL;DR: In this article, the bioreduction with immobilized baker's yeast of several ketones was carried out in a 10:1 [bmim]PF6 ionic liquid/water mix.

TL;DR: In this paper, a (R,R)-Di-μ-oxo Ti(salen) 4 was found to serve as an efficient catalyst for asymmetric oxidation of various sulfides with hydrogen peroxide.

TL;DR: Bis(trimethylsilyl) amides of the type Ln[N(TMS)2]3 have been found to be competent catalysts for representative intramolecular alkene hydroaminations as mentioned in this paper.