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Showing papers in "Tetrahedron Letters in 1999"


Journal ArticleDOI
TL;DR: In this article, an air and water tolerant, imidazolinylidene-substituted ruthenium-based complex has been prepared starting from RuCl2(CHPh)(PCy3)2 and shown to exhibit increased ring-closing metathesis activity at elevated temperature compared to that of the parent complex.

793 citations


Journal ArticleDOI
TL;DR: In this article, a novel synthesis of functional dithioesters, dithiocarbamates, xanthates and trithiocalarbonates is described, which is compatible with a wide range of functionalities (e.g. carboxy, hydroxy and nitrile).

430 citations


Journal ArticleDOI
TL;DR: The Diels-Alder cycloaddition reaction between methyl acrylate and cyclopentadiene has been investigated in a number of air and moisture stable ionic liquids as discussed by the authors.

377 citations


Journal ArticleDOI
TL;DR: Ruthenium carbene complexes 2-8 bearing one or two imidazolin-2-ylidene ligands are highly active catalysts for all types of ring closing metathesis reactions (RCM) as mentioned in this paper.

368 citations


Journal ArticleDOI
TL;DR: Copper-catalyzed Narylation of imidazoles can be accomplished using (CuOTf)2·benzene as a copper source and Cs2CO3 as a base in xylenes at 110-125 °C as mentioned in this paper.

356 citations


Journal ArticleDOI
TL;DR: In this paper, the reaction of aldehydes, β-dicarbonyl compounds and urea (Biginelli reaction) has been performed over solid acid catalysis, under solventless conditions or in water affording dihydropyrimidines in good yield and selectivity.

281 citations


Journal ArticleDOI
TL;DR: In this paper, the ring-closing metathesis (RCM) products of reactions utilizing RuCl2(CHPh)(PCy3)2 (1) as a catalyst were successfully purified of unwanted ruthenium using a water-soluble coordinating phosphine, tris(hydroxymethyl)phosphine, P(CH2OH)3.

276 citations


Journal ArticleDOI
TL;DR: The synthesis of two water soluble dendrimers and the formation of water soluble inclusion complexes with a variety of small, hydrophobic guest molecules is described, when these guest molecules are drug moieties.

210 citations


Journal ArticleDOI
TL;DR: In this article, 4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) was quantitatively synthesized by coupling of 2-chloro-4, 6-dimethoxy and 1, 3, 5-triazine and N-methylmethylmorpholine in THF, and fully characterized.

189 citations


Journal ArticleDOI
TL;DR: In this article, a novel and efficient means of effecting the cyclodehydration of 1,2-diacylhydrazines to provide 1,3,4-oxadiazoles was reported.

177 citations


Journal ArticleDOI
TL;DR: The utility of room temperature chloroaluminate ionic liquids as solvent and catalyst for the synthetically important Diels-Alder reaction was studied in this article, where the AlCl3-1-ethyl-3-methyl-1H-imidazolium chloride medium proved to be ideally suited for Diels Alder reactions.

Journal ArticleDOI
TL;DR: In this paper, a variety of chiral β-hydroxy-α-amino acids and derivatives thereof can be synthesized enantioselectively using the aldol reaction of an aldehyde, the glycinate 1 and the cinchonidine-derived catalyst 2.

Journal ArticleDOI
TL;DR: In this paper, the secondary alcohols (1g,h) and tertiary alcohol 1i, as well as tertiary alkyl ether 4i, did not react with the HSiEt 3 ( B(C 6 F 5 ) 3 reducing reagent at all.

Journal ArticleDOI
TL;DR: In this article, a catalytic cycle has been proposed for the acylation reaction of alcohols, phenols, amines and thiols with acetic anhydride in CH 2 Cl 2 or acetic acid.

Journal ArticleDOI
TL;DR: In this paper, a one-pot synthesis of annulated pyridines, pyrazines and pyrimidines was described in the presence of recyclable montmorillonite K 10 clay under solvent-free conditions using microwave irradiation.

Journal ArticleDOI
TL;DR: The chiral salen Mn(III) complexes were heterogenized on the siliceous MCM-41 by a new grafting method using (3-aminopropyl) trimethoxysilane and 2,6-diformyl-4-tert-butylphenol as mentioned in this paper.

Journal ArticleDOI
TL;DR: Polymer supported ruthenium catalyst 8 was found to be an effective catalyst for ring closing metathesis as mentioned in this paper, and the rate of reaction and activity was comparable to that of homogeneous catalyst 1.

Journal ArticleDOI
TL;DR: Iodonium-ion promoted glycosylations in 1,4-dioxane/toluene with galactosyl donors having an electron-donating neighboring group participating functionality at C-4 give exceptional high α-anomeric selectivities.

Journal ArticleDOI
TL;DR: The new palladacycle catalyst 5 was synthesized, and this Pd catalyst showed high catalytic activity with turnover numbers of up to 8 900 000 (mol product per mol Pd) as discussed by the authors.

Journal ArticleDOI
TL;DR: The cross-coupling reaction of acid chlorides with arylboronic acids, using catalytic amounts of Pd(PPh3)4 and five equivalents Cs2CO3, under anhydrous conditions provides a new method for the synthesis of ketones in good to moderate yields as discussed by the authors.

Journal ArticleDOI
TL;DR: In this paper, green 3,4:9,10-perylenebis (dicarboximide) dyes that both donate and accept electrons were synthesized under mild conditions in high yields.

Journal ArticleDOI
TL;DR: In this paper, a tripodal receptor for halide anions has been synthesized, which has three imidazolium groups connected through a 1,3,5-trimethylbenzene spacer, and has been shown to bind strongly Cl−, Br− and I− anions in CD3CN through electrostatic interactions and CH···X− hydrogen bonds.

Journal ArticleDOI
TL;DR: In this article, the polymerization of 2-iodo-3-alkylthiophenes using a Heck-type reaction withPd(OAc)2/NBu4Br as catalytic system is reported leading to expected functionalized oligomers with good yields.

Journal ArticleDOI
TL;DR: In the presence of catalytic amounts of cesium hydroxide (CsOH·H2O), alcohols, substituted anilines and heterocyclic amines undergo an addition in NMP to phenylacetylene leading to functionalized enol ethers and enamines.

Journal ArticleDOI
TL;DR: In this article, a system comprised of manganese(II) acetate or sulfate, 1,4,7-trimethyl-1, 4, 7-triazacyclonononane (TMTACN) and ascorbic acid efficiently catalyzes the epoxidation of olefins and the oxidation of alcohols with hydrogen peroxide.

Journal ArticleDOI
TL;DR: In this article, 4-and 5-methyl thiazole is readily alkylated with n-butyl bromide followed by anion exchange of Br− for BF4− to give mobile, room-temperature ionic liquids.

Journal ArticleDOI
TL;DR: A dependable high yielding palladium catalyzed aryl bromide cyanation procedure has been developed in this paper, which features extremely low levels of palladium and DPPF ligand.

Journal ArticleDOI
TL;DR: In this article, a nonphotochemical methodology was proposed for enantioselective synthesis of a helical skeleton employing the Ni(cod) 2 /(S)-(−)-MOP catalytic system.

Journal ArticleDOI
TL;DR: The synthesis of pyrroles by reaction of hexane-2,5-dione with primary amines has been shown to occur in less than 2 minutes under microwave activation.

Journal ArticleDOI
TL;DR: Sansalvamide exhibited selective in vitro cytotoxicity toward COLO 205 colon and SK-MEL-2 melanoma cancer cell lines.