Showing papers in "Organic Letters in 2006"

TL;DR: Five increasingly sophisticated aromaticity indexes, based on nucleus-independent chemical shifts (NICS), were evaluated against a uniform set of aromatic stabilization energies (ASE) for 75 mono- and polyheterocyclic five-membered rings to find the most fundamentally grounded index, NICS(0)pizz.

TL;DR: A new fluorescent probe was synthesized and displayed selective Cu( II)-amplified absorbance and fluorescence emission above 500 nm in neutral buffered media and the detection of Cu(II) by 1 at a lower micromolar level was successful even in buffered water.

TL;DR: The development of the Cu(I)-catalyzed Huisgen cycloaddition (click) reaction for the multiple postsynthetic labeling of alkyne-modified DNA is reported.

TL;DR: Under special conditions, N-phthaloyl-alpha-amino acid amides of 8-aminosquinoline can be either acetoxylated or arylated selectively at the beta-carbon.

TL;DR: A new fluorescent probe 3 was synthesized, and it exhibited high selectivity for Fe(III) over other commonly coexistent metal ions in both ethanol and water with significant enhancement of visible color and fluorescence.

TL;DR: A new cobalt-catalyzed coupling of aryl halides with thiophenols and alkanethiols is reported, which represents an interesting addition to previously known methods to synthesize thioethers.

TL;DR: Energies computed by B3LYP and other popular DFT functionals are flawed by systematic errors, which can become considerable for larger molecules, as illustrated by the isodesmic stabilization energies of n-alkanes.

TL;DR: Peroxide-based oxidants in the Pd(OAc)(2)-catalyzed acetoxylation and etherification of arene and alkane C-H bonds proved particularly effective, and these transformations were applied to a wide variety of substrates.

TL;DR: A new chemosensor based on rhodamine B thiohydrazide was found to show a reversible dual chromo- and fluorogenic response toward Hg2+ in aqueous solution in a highly selective and sensitive manner.

TL;DR: Intermolecular additions of the O-H bonds of phenols and alcohols and the N-H Bonds of sulfonamides and benzamide to olefins catalyzed by 1 mol % of triflic acid and studies to define the relationship between these reactions and those catalyzing by metal triflates are reported.

TL;DR: This inexpensive and commercially available tripod ligand has been demonstrated to facilitate the copper-catalyzed cross-coupling reactions of aryl iodides with amides, thiols, and phenols to afford the corresponding desired products in good to excellent yields.

TL;DR: A commercially available pharmaceutical, tetramisole, was found to be a competent enantioselective acylation catalyst and its benzannellated analogue, benzotetramisoles (BTM), produced outstanding enantiOSElectivities in kinetic resolution of secondary benzylic alcohols.

TL;DR: Extrapolation of HOMO-LUMO gaps at the B3LYP/6-31G(d) level of theory predict accurately (within 0.1-0.2 eV) the band gaps of conjugated polymers only when long (at least 20-mer) pi-conjugated oligomers are used for the extrapolation.

TL;DR: A mild palladium-catalyzed method for the regioselective chlorination, bromination, and iodination of arene C-H bonds using N-halosuccinimides as oxidants is described.

TL;DR: Propargylamines have been synthesized by a gold(III) salen complex-catalyzed three-component coupling reaction of aldehydes, amines, and alkynes in water in excellent yields at 40 degrees C with excellent diastereoselectivities.

TL;DR: 4-Hhydroxyproline has been anchored to a polystyrene resin through click chemistry, and the resulting catalyst has been successfully applied to the direct aldol reaction in water.

TL;DR: Asymmetric Michael additions of cyclohexanone to both aryl and alkyl nitrooleolefins in the presence of organocatalyst 2b and n-butyric acid afford adducts 5 with high diastereoselectivity and enantioselectivities.

TL;DR: Several DFT methods were found to be unreliable for computing hydrocarbon isomer energy differences, and the use of higher level, non-DFT energy single points computed at DFT-optimized structures is recommended.

TL;DR: A new cyclam derivative having two different fluorophores of pyrene and NBD subunits exhibited a selective Hg2+/Cu2+-induced OFF-ON-OFF type of signaling pattern that can be utilized for the construction of functional supramolecular switching systems.

TL;DR: A new, selective chemosensor has been developed to detect cyanide in water at micromolar concentrations and the selectivity of the system in aqueous media for CN- over other anions is remarkably high.

TL;DR: The efficient addition of bis(pinacolato)diboron to alpha,beta-unsaturated carbonyl compounds with a copper-diphosphine catalyst has been carried out and a dramatic rate acceleration of the reaction was realized by adding alcohol additives.

TL;DR: A polymer-supported catalyst for Huisgen's [3+2] cycloaddition reaction between azides and alkynes was prepared from copper(I) iodide and Amberlyst A-21 and has shown good activity, stability, and recycling capabilities.

TL;DR: In this article, a catalyst-free conjugate addition of thiols to α,β-unsaturated carbonyl compounds in water was reported, which constitutes an easy, highly efficient and green synthesis of β-sulfido carbonyls.

TL;DR: The selective and sensitive signaling behaviors were found to originate from the Hg2+ ion induced transformation of the very weak fluorescent thioamide derivative into a highly fluorescent amide analogue.

TL;DR: By recovering the Au(III) catalyst, a recyclable catalytic system is developed with over 8300 product turnovers attained for the cycloisomerization of 1-phenyl-buta-2,3-dien-1-one.

TL;DR: TEM coupled with EDX analysis indicate the formation of Pd nanoparticles within the immobilized IL layer and the application of the resulting catalyst in the Heck reaction of a variety of different haloarenes is described.

TL;DR: 4,7-Dimethoxy-1,10-phenanthroline was found to be an efficient ligand for the copper-catalyzed N-arylation of imidazole with aryl iodides and bromides under mild conditions.

TL;DR: Stereoselective, carbene-mediated redox esterification of alkynyl aldehydes provides mild and atom economical access to (E)-configurated, α,β-unsaturated carboxylic esters.

TL;DR: The versatility of supramolecular chemistry has been exploited in constructing nanovalves based on mesoporous silica MCM-41 and the mutual recognition between secondary dialkylammonium ions and dibenzo[24]crown-8 (DB24C8).

TL;DR: These palladium complexes catalyze the efficient C-H arylation of SEM-protected azole heteroarenes and thus provide a good method for preparation of a wide range of arylated free (NH)-azoles including pyrroles, indoles, imidazoles, and imidazo[1,2-a]pyridines.