Showing papers in "Organic Letters in 1999"

TL;DR: These air- and water-tolerant complexes were shown to exhibit an increased ring-closing metathesis activity at elevated temperature when compared to that of the parent complex 2 and the previously developed complex 3.

TL;DR: In this paper, aryl halides or benzoic anhydride with alkenes can be performed with excellent yields in room-temperature ionic liquids, which provide a medium that dissolves the palladium catalyst and allows the product and byproducts to be easily separated.

TL;DR: A novel catalytic enantioselective Strecker synthesis of chiral alpha-amino nitriles and alpha-AMino acids is described and analyzed with regard to the possible mechanistic basis for stereoselectivity.

TL;DR: Trisubstituted alkenes have been prepared for the first time via intermolecular olefin cross-metathesis, using 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene ruthenium alkylidene complexes 3a,b in good yields with moderate E selectivity.

TL;DR: In this article, a simple, efficient, and general method was developed for the synthesis of α-amino phosphonates through a one-pot reaction of aldehydes and ketones with amines in the presence of indium(III) chloride as a catalyst.

TL;DR: The solvent-free condensation of pyrrole and pentafluorobenzaldehyde leads to a variety of products, of which three have been isolated and fully characterized as mentioned in this paper.

TL;DR: In this article, the oxidative coupling of arenes with olefins has been performed efficiently in the presence of catalytic amounts of palladium acetate and benzoquinone (BQ) with tert-butyl hydroperoxide as the oxi...

TL;DR: The new crystalline phosphate reagent 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT) mediates amide bond formation with a remarkable resistance to racemization.

TL;DR: Efficient Pd-catalyzed Heck coupling methodology was employed to provide two new fluorene derivatives with phosphonate (2) and nitro (3) electron-withdrawing functionalities as discussed by the authors.

TL;DR: Biological screening studies indicated that pseudopteroxazole is a potent growth inhibitor of Mycobacterium tuberculosis H37Rv, while seco-pseudopterxazole shows moderate to strong inhibitorial activity.

TL;DR: In this paper, a combination of palladium and an imidazolium chloride was used as catalyst precursor in the amination of aryl chlorides, which proved general and efficient.

TL;DR: The chiral rhodium complex 1a, and its enantiomer 1b were found to provide superior catalysts for the rapid, high-yielding, asymmetric transfer hydrogenation of some heterocyclic imines, using an HCO2H-Et3N azeotrope as the hydrogen source.

TL;DR: In this article, three-component Mannich-type reactions of aldehydes, amines, and ketones were efficiently catalyzed by dodecylbenzenesulfonic acid at ambient temperature in water to give various β-amino ketones in good yields.

TL;DR: With the proper choice of palladium catalyst, ligand, and base, five-, six-, and seven-membered rings are formed efficiently from secondary amide or secondary carbamate precursors, offering significant improvements to currently existing methodology.

TL;DR: In this paper, a rational analysis of the mechanistic basis for this strong absolute stereochemical control by the chiral catalyst is presented along with a high-enantioselective (up to 130:1) epoxidation of a variety of α, β-enones to form α,β-epoxy ketones.

TL;DR: It is found that methanesulfonic acid catalyzed condensation of pyrrole and benzaldehyde followed by DDQ oxidation provides N-confused tetraphenylporphyrin (NC-TPP) in up to 39% yield in analytical scale experiments.

TL;DR: The reaction of substituted glycols with catalytic dibutyltin oxide, stoichiometric p-toluenesulfonyl chloride, and triethylamine in CH2Cl2 resulted in the complete and rapid sulfonylation at the primary alcohol as mentioned in this paper.

TL;DR: Dienes 2a-e were used to study allylic substituent effects in the ring-closing metathesis reaction (RCM) and both the steric and electronic character of the allylic Substuents were found to influence alkene reactivities.

TL;DR: Asymmetric reduction of benzil with RuCl[(S,S)-Tsdpen)(η6-p-cymene) in a mixture of formic acid and triethylamine proceeds with a substrate/catalyst molar ratio of 1000−2000 to give (R,R)-hydrobenzoin quantitatively with high diastereomeric (97% de) and enantiomeric purities (>99% ee), in which the benzoin intermediate with a chirally labile stereogenic center is converted to one major

TL;DR: In this article, the authors show that reaction proceeds more rapidly with the corresponding boronic acids, and the choice of phosphine ligand does not signifcantly influence the overall efficiency of addition.

TL;DR: Ab initio calculations reveal a significant binding interaction between water and hexafluorobenzene in a geometry that points the oxygen lone pairs directly into the face of the pi system.

TL;DR: In this article, a new procedure for both inter- and intramolecular homocoupling of aryl halides (Ullmann reaction) using catalytic palladium in the presence of hydroquinone, a homogeneous reductant, is described.

TL;DR: In this paper, an efficient solid-state oxidation of organic molecules is described using a stable, inexpensive, and easily handled reagent, the urea−hydrogen peroxide adduct.

TL;DR: In this article, the reactions of aryl- and alkenylsilanols with organic halides were found to proceed in a catalyst system of 5 mol % of Pd(PPh3)4 and Ag2O (1 equiv) to give the corresponding coupling products in up to 84% yield.

TL;DR: In this paper, 3-substituted isoquinolines and pyridines were synthesized by coupling aryl, alkenyl, and alkyl substituents with the tert-butylimines of o-iodobenzaldehydes or 3-halo-2-alkenals.

TL;DR: A catalytic method for the enantioselective ring opening of meso aziridines by TMSN3 is described and Tridentate Schiff base chromium complexes derived from 1-amino-2-indanol were identified as the optimal catalysts.

TL;DR: In this article, the potential of the recently developed palladium-catalyzed trimerization of arynes for the synthesis of strained polycyclic hydrocarbons was evaluated.

TL;DR: In this article, a palladium-catalyzed cross-coupling reaction of organoindium compounds with vinyl and aryl triflates or iodides is described.

TL;DR: The scope of the palladium-catalyzed cross coupling reaction of aryl halides with phenyltrimethoxysilane has been expanded to include aryL bromides, heteroaryl bromide, and aryal chlorides.

TL;DR: This work catalyzes the enantioselective amination of enolsilanes with azodicarboxylate derivatives with the use of an alcohol additive and achieves catalyst turnover in greater than 95% ee.