Pd-Catalyzed Vinylation of Aryl Halides with Inexpensive Organosilicon Reagents Under Mild Conditions.

Pd-catalyzed Hiyama vinylation reaction of non-activated aryl chlorides and bromides under mild conditions was developed. The use of efficient vinyl donors and electron-rich sterically hindered phosphine ligands was critical for the success of the reaction. The products of this transformation can be used for Am/Cm separation, an important challenge in nuclear fuel reprocessing.

Radical Carbofluorination of Unactivated Alkenes with Fluoride Ions.

The copper-assisted radical carbofluorination of unactivated alkenes with fluoride ions is described. With [Cu(L3)F]HO (L3 = 4,4'-di(methoxycarbonyl)-2,2'-bipyridine) as the fluorine source and [Ag(DMPhen)(MeCN)]BF (DMPhen = 2,9-dimethyl-1,10-phenanthroline) as the chloride scavenger, the reaction of unactivated alkenes with CCl in acetonitrile provided the corresponding carbofluorination products in satisfactory yields. The protocol exhibited a wide functional group compatibility and broad substrate scope and could be extended to the use of a variety of activated alkyl chlorides other than CCl.

Selective Radical Fluorination of Tertiary Alkyl Halides at Room Temperature.

Direct fluorination of tertiary alkyl bromides and iodides with Selectfluor is described. The halogen-exchange fluorination proceeds efficiently in acetonitrile at room temperature under metal-free conditions and exhibits a wide range of functional group compatibility. Furthermore, the reactions are highly selective in that alkyl chlorides and primary and secondary alkyl bromides remain intact.

Mechanism of Nickel-Catalyzed Suzuki-Miyaura Coupling of Amides.

The Ni-catalyzed Suzuki-Miyaura coupling of N-tert-butoxycarbonyl (N-Boc)-protected amides provides a versatile strategy for the construction of C-C bonds. In this study, density functional theory (DFT) methods have been used to elucidate the mechanism of this reaction, with particular emphasis on the roles of N-Boc, K PO and H O. Our results corroborated those of previous reports, indicating that the overall catalytic cycle consists of three steps, including oxidative addition, transmetalation, and reductive elimination.

Mechanism of Ligand-Controlled Regioselectivity-Switchable Copper-Catalyzed Alkylboration of Alkenes.

Cu-catalyzed alkylboration of alkenes with bis(pinacolato)diboron ((Bpin)2 ) and alkyl halides provides a ligand-controlled regioselectivity-switchable method for the construction of complex boron-containing compounds. Here, we employed DFT methods to elucidate the mechanistic details of this reaction and the origin of the different regioselectivity induced by Xantphos and Cy-Xantphos. The calculation results reveal that the catalytic cycle mainly proceeds through the migratory insertion of alkenes on Cu-Bpin complex, the oxidative addition of alkyl halides, and the reductive elimination of a C-C bond.

Mechanistic Study on Gold-Catalyzed Highly Selective Hydroamination of Alkylidenecyclopropanes.

Density functional theory calculations have been carried out to study the mechanism of the gold-catalyzed highly selective hydroamination of alkylidenecyclopropanes. Two main mechanisms (i.e.

Mechanism of Boron-Catalyzed N-Alkylation of Amines with Carboxylic Acids.

Mechanistic study has been carried out on the B(C6F5)3-catalyzed amine alkylation with carboxylic acid. The reaction includes acid-amine condensation and amide reduction steps. In condensation step, the catalyst-free mechanism is found to be more favorable than the B(C6F5)3-catalyzed mechanism, because the automatic formation of the stable B(C6F5)3-amine complex deactivates the catalyst in the latter case.

Density functional theory investigation on Pd-catalyzed cross-coupling of azoles with aryl thioethers.

In the present study, a density functional theory (DFT) study has been carried out on the Pd-catalyzed coupling of azoles with aryl thioethers. Our effort is mainly put into identifying the most feasible catalytic cycle, and especially the origin of chemoselectivity for the exclusive aromatic Csp(2)-S bond activation (in the presence of an alkyl Csp(3)-S bond). The coupling mainly consists of three steps: C-S activation, NaO(t)Bu mediated C-H palladation, and reductive elimination.

Computational Study of Formic Acid Dehydrogenation Catalyzed by Al(III)-Bis(imino)pyridine.

The mechanism of formic acid dehydrogenation catalyzed by the bis(imino)pyridine-ligated aluminum hydride complex (PDI(2-))Al(THF)H (PDI=bis(imino)pyridine) was studied by density functional theory calculations. The overall transformation is composed of two stages: catalyst activation and the catalytic cycle. The catalyst activation begins with O-H bond cleavage of HCOOH promoted by aluminum-ligand cooperation, followed by HCOOH-assisted Al-H bond cleavage, and protonation of the imine carbon atom of the bis(imino)pyridine ligand.

Ligand-Controlled Regiodivergent Copper-Catalyzed Alkylboration of Alkenes.

A novel copper-catalyzed regiodivergent alkylboration of alkenes with bis(pinacolato)diboron and alkyl halides has been developed. The regioselectivity of the alkylboration was controlled by subtle differences in the ligand structure. The reaction thus enables the practical, regiodivergent synthesis of two different alkyl boronic esters with complex structures from a single alkene.

Mechanism of Nickel(II)-Catalyzed Oxidative C(sp²)-H/C(sp³)-H Coupling of Benzamides and Toluene Derivatives.

The Ni-catalyzed C(sp(2))-H/C(sp(3))-H coupling of benzamides with toluene derivatives was recently successfully achieved with mild oxidant iC3F7I. Herein, we employ density functional theory (DFT) methods to resolve the mechanistic controversies. Two previously proposed mechanisms are excluded, and our proposed mechanism involving iodine-atom transfer (IAT) between iC3F7I and the Ni(II) intermediate was found to be more feasible.

Room-Temperature Decarboxylative Couplings of α-Oxocarboxylates with Aryl Halides by Merging Photoredox with Palladium Catalysis.

Enabled by merging iridium photoredox catalysis and palladium catalysis, α-oxocarboxylate salts can be decarboxylatively coupled with aryl halides to generate aromatic ketones and amides at room temperature. DFT calculations suggest that this reaction proceeds through a Pd(0) -Pd(II) -Pd(III) pathway, in which the Pd(III) intermediate is responsible for reoxidizing Ir(II) to complete the Ir(III) -*Ir(III) -Ir(II) photoredox cycle.

Corrigendum.

[This corrects the article on p. 253 in vol. 5, PMID: 25425503.

Fluorescent recognition of uranyl ions by a phosphorylated cyclic peptide.

Fluorescent recognition of uranyl ions was achieved using a phosphorylated cyclic peptide, which can be used as a fluorescent sensor for the detection of uranyl ions with high selectivity and sensitivity.

"One-pot" synthesis of amidoxime via Pd-catalyzed cyanation and amidoximation.

A novel "one-pot" reaction was developed for the synthesis of aryl or heteroaryl-substituted amidoxime compounds containing various functional groups. Fluorescence titration experiments coupled with theoretical analysis revealed that the steric hindrance and electronic effects of substituents influence the binding ability of the amidoxime compounds to uranyl ions.

Mechanistic origin of chemoselectivity in thiolate-catalyzed Tishchenko reactions.

The thiolate-catalyzed Tishchenko reaction has shown high chemoselectivity for the formation of double aromatic-substituted esters. In the present study, the detailed reaction mechanism and, in particular, the origin of the observed high chemoselectivity, have been studied with DFT calculations. The catalytic cycle mainly consisted of three steps: 1,2-addition, hydride transfer, and acyl transfer steps.

Accurate predictions of C-SO2R bond dissociation enthalpies using density functional theory methods.

The dissociation of the C-SO2R bond is frequently involved in organic and bio-organic reactions, and the C-SO2R bond dissociation enthalpies (BDEs) are potentially important for understanding the related mechanisms. The primary goal of the present study is to provide a reliable calculation method to predict the different C-SO2R bond dissociation enthalpies (BDEs). Comparing the accuracies of 13 different density functional theory (DFT) methods (such as B3LYP, TPSS, and M05 etc.

Quantum-chemical predictions of pKa's of thiols in DMSO.

The deprotonation of thiols (on the S-H bond) is widely involved in organic and bio-organic reactions. With the aid of density functional theory (DFT) calculations, the present study focuses on predicting the pKa's of thiols. Efforts were first put in searching for an appropriate computational method.

Computational study on mechanism of Rh(III)-catalyzed oxidative Heck coupling of phenol carbamates with alkenes.

A systematic theoretical study on the Rh-catalyzed oxidative Heck-coupling of phenol carbamates with alkenes is carried out. Two possible mechanisms (i.e.

Mechanism of arylboronic acid-catalyzed amidation reaction between carboxylic acids and amines.

Arylboronic acids were found to be efficient catalysts for the amidation reactions between carboxylic acids and amines. Theoretical calculations have been carried out to investigate the mechanism of this catalytic process. It is found that the formation of the acyloxyboronic acid intermediates from the carboxylic acid and the arylboronic acid is kinetically facile but thermodynamically unfavorable.

Alternative mechanistic explanation for ligand-dependent selectivities in copper-catalyzed N- and O-arylation reactions.

The ligand-dependent selectivities in Ullmann-type reactions of amino alcohols with iodobenzene by β-diketone- and 1,10-phenanthroline-ligated Cu(I) complexes were recently explained by the single-electron transfer and iodine atom transfer mechanisms (Jones, G. O., Liu, P.

Highly diastereoselective domino synthesis of 6-spirosubstituted pyrido[2,3-d]pyrimidine derivatives in water.

A highly diastereoselective domino reaction of 2,6-diaminopyrimidine-4-one with structurally diverse aryl aldehydes and various barbituric acids in water under microwave irradiation is described. The products are 6-spiro-substituted pyrido[2,3-d]pyrimidines with high diastereoselectivities (up to 99: 1) in which the major diastereomer bears a cis relationship between substituents at the 5- and 7-positions. Furthermore, the mechanism for diastereoselectivity was confirmed by DFT (B3LYP) calculations.

[A sero-epidemiologiecal study on hepatitis B among general population in Beijing].

Objective: To explore the serological infection rate of hepatitis B virus (HBV) in general population aged over one year old in Beijing and to provide information for control and prevention of the disease.

Methods: A multistage randomized cluster sampling was carried out in general population of Beijing, aged over one year old. Every study subject's hepatitis B immunization history and main risk factors were investigated through questionnaire.