Showing papers in "Organic Letters in 2002"

TL;DR: A series of 6,13-disubstituted pentacenes, in which the substituents are functionalized ethyne units, were synthesized and analyzed by X-ray crystallography and were highly soluble and oxidatively stable and exhibited a significant amount of pi-stacking in the crystal.

TL;DR: A mild method for the copper-catalyzed amination of aryl iodides using CuI as the catalyst and ethylene glycol as ligand in 2-propanol is reported.

TL;DR: Epoxides dissolved in molten tetralkylammonium salts bearing halides as counterions are converted into cyclic carbonates under atmospheric pressure of carbon dioxide.

TL;DR: An efficient copper-catalyzed carbon-sulfur bond formation reaction was developed and is particularly noteworthy given its experimental simplicity, high generality, and exceptional level of functional group toleration and the low cost of the catalyst system.

TL;DR: The fluorescent photoinduced electron transfer chemosensors 2 and 3 were designed for the recognition of anions possessing two binding sides such as dicarboxylates and pyrophosphate; the anion recognition in DMSO takes place through the two charge neutral thiourea receptor sites with concomitant PET quenching of the anthracene moiety.

TL;DR: A combination of NMR, IR, and ab initio techniques reveals the striking structural similarities of an exemplary H-bonded complex of an N-acyloxazolidinone with an N,N'-disubstituted electron-poor thiourea and the corresponding Lewis acid complex.

TL;DR: An efficient, user-friendly procedure for the oxidation of alcohols using IBX is described, which gives excellent yields of the corresponding carbonyl compounds.

TL;DR: A simple and mild method for the coupling of aryl iodides and aliphatic alcohols that does not require the use of alkoxide bases is described and the cross-coupling of an optically active benzylic alcohol with an unactivated aryal halide was demonstrated to proceed with complete retention of configuration.

TL;DR: A mild, palladium-free synthetic protocol for the cross-coupling reaction of aryl iodides and thiols using 10 mol% CuI and 10 mol % neocuproine in toluene at 110 degrees C is reported.

TL;DR: The PdCl2(PPh3)2-catalyzed Sonogashira coupling reaction, in good to high yields, was performed in an ionic liquid in the absence of a copper salt to allow for the facile separation and recycling of the catalyst.

TL;DR: Perturbing influences, such as strain and the presence of heteroatoms, complicate the evaluation of aromatic stabilization energies (ASE), but these complications are overcome easily by employing the "isomerization method".

TL;DR: Imidazol-2-ylidenes, a family of N-heterocyclic carbenes (NHC), are efficient catalysts in the transesterification between esters and alcohols and form efficiently the corresponding esters in very short reaction times.

TL;DR: The use of nucleophilic N-heterocyclic carbenes as efficient transesterification catalysts were found to be mild, selective, and more active than traditional organic nucleophiles.

TL;DR: The ligand-free palladium catalysis of the Suzuki reaction in water using microwave heating is reported, using low palladium loadings and is useful for couplings involving boronic acids and aryl iodides, bromides, and chlorides.

TL;DR: The direct Michael addition of aldehydes and ketones to nitrostyrene, catalyzed by N-i-Pr-2,2'-bipyrrolidine, is described, and the desired 1,4-adducts are obtained in excellent yield with enantioselectivities up to 85% ee and dr up to 95:5 of the syn product.

TL;DR: Novel elongated push-push fluorophores synthesized by 2-fold Sonogashira or Wittigminus signHorner reactions and derivatives combining enhanced two-photon absorption cross section in the visible red and high fluorescence quantum yield have been obtained.

TL;DR: The rate of the heterogeneous electron-transfer reaction between the complexed viologen dication and cation radical remained fast in the voltammetric time scale and the binding constants were measured.

TL;DR: PEG has been used as a solvent medium for regioselective Heck reactions with easy recyclability of solvent and Pd catalyst for the first time.

TL;DR: Copper salt catalyzed ether formation from aryl bromides or iodides and phenols, 2,2,6,6-tetramethylheptane-3,5-dione (TMHD) was found to greatly accelerate the ordinarily difficult reaction, making it occur under more moderate temperatures and reaction times.

TL;DR: A modification of the Sonogoshira coupling reaction employing an amidine base and a substoichiometric amount of water generates symmetrical and unsymmetrical bisarylethynylenes in one pot through in situ deprotection of trimethylsilylethunylene-added intermediates.

TL;DR: A positively charged tripodal receptor with nitro groups in the imidazolium rings was designed, synthesized, and characterized for its anion binding strength and shows strong affinity and high selectivity for Cl- through (C-H)+- - - -X(-) hydrogen bonds.

TL;DR: The Heck reaction of aryl chlorides was investigated in the presence of defined monocarbenepalladium(0) complexes to provide the corresponding cinnamic esters and stilbenes in (n)Bu(4)NBr as a ionic liquid in good to excellent yields.

TL;DR: Pi-deficient heteroaromatic thioethers undergo efficient palladium-catalyzed cross-coupling with boronic acids mediated by copper(I) thiophene-2-carboxylate.

TL;DR: A simple and mild TEMPO-CuCl catalyzed aerobic oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones in ionic liquid with no trace of overoxidation to carboxylic acids has been developed.

TL;DR: The reaction of boronic acids with aryl, heteroaryl, and alkyl N-thioimides in the presence of catalytic quantities of a Cu(I) carboxylate affords good to excellent yields of thioethers.

TL;DR: Catalytic enantioselective nitroaldol reactions promoted by modified ligands led to efficient syntheses of the beta-receptor agonists (-)-denopamine and (-)-arbutamine.

TL;DR: A new iridium-catalyzed oxidative cyclization of amino alcohols has been revealed andIndole derivatives are synthesized in good to excellent yields from 2-aminophenethyl alcohols by means of a [CpIrCl(2)](2)/K(2)CO(3) catalytic system.

TL;DR: In this paper, a Pd(OAc)2/diazabutadiene system was developed for the catalytic cross-coupling of aryl halides with arylsboronic acids.

TL;DR: 1,3,5-Trisubstituted pyrazolines and Hantzsch 1,4-dihydropyridine were converted to the corresponding pyrazoles and pyridines effectively by the treatment of a catalytic amount of Pd/C in acetic acid.

TL;DR: The catalytic enantioselective electrophilic fluorination promoted by quaternary ammonium salt from cinchonine as a phase-transfer catalyst is described, resulting in high yields of alpha-fluoro beta-keto esters in exellent yields with good to moderate enantiomeric excesses.