Insight into the Metal-Free Reduction of Isocyanates to N-Methyl Anilines at Room Temperature.

A simple and sustainable protocol has been developed to reduce isocyanates to the N-methyl anilines under metal-free conditions. The reaction proceeds with BF ⋅ OEt as a catalyst and ammonia borane as a hydrogen source in THF at room temperature, leading to the formation of a wide range of substituted aniline derivatives. Control experiments and deuterium labeling studies were performed to understand the mechanism of the present procedure.

Unexpected structural preference with metallophilic Ag-Au contacts in silver(I)-N-heterocyclic carbene cluster; experimental and theoretical approach.

A novel synthetic donor-atom-selective approach has been adopted for the synthesis of a heterobimetallic cluster of a new NCN-pincer, 1,3-bis-(1-methyl-1-benzo[]imidazol-2-yl-methyl)-1-imidazol-3-ium hexafluorophosphate (1·HPF). The complex [Ag(1)][PF] (2) has been prepared the AgO route; which undergoes transmetallation to yield a cluster that seems to be the first example of the heterobimetallic trinuclear system [Au-Ag(1)Cl][PF], 3. Finally, the trinuclear cluster geometries of 2 and 3 were confirmed SCXRD studies.

Unexpected C-H bond activation in coordinated 7,8-benzoquinoline: synthesis and characterisation of heteroleptic Ir(iii)-7,8-benzoquinoline complexes.

Two iridium(iii) complexes were isolated the reaction of pyridine-2-aldoxime (Hpyrald) with 7,8-benzoquinoline (benzq)-derived iridium starting material, namely [(benzq)Ir(μ-Cl)Ir(benzq)] (1). Among the two complexes, [Ir(benzq)(pyrald)] (2) and [Ir(benzq-κN,κC)(benzq-κC)(Hpyrald)(Cl)] (3), the later displayed unusual C-H bond activation in one of the coordinated 7,8-benzoquinoline rings. The complex (2) presented a usual structure as expected.

Doubling Förster Resonance Energy Transfer Efficiency in Proteins with Extrinsic Thioamide Probes: Implications for Thiomodified Nucleobases.

Designing a potential protein-ligand pair is pivotal, not only to track the protein structure dynamics, but also to assist in an atomistic understanding of drug delivery. Herein, the potential of a small model thioamide probe being used to study albumin proteins is reported. By monitoring the Förster resonance energy transfer (FRET) dynamics with the help of fluorescence spectroscopic techniques, a twofold enhancement in the FRET efficiency of 2-thiopyridone (2TPY), relative to that of its amide analogue, is observed.

Asymmetric Cooperative Catalysis in a Three-Component Reaction: Mechanism and Origin of Enantio- and Diastereoselectivities.

Mechanistic insights gained through density functional theory (DFT M06 and B3LYP) computations on a three-component cooperative asymmetric catalytic reaction between a diazo ester, a carbamate, and an imine, catalyzed by dirhodium acetate and chiral phosphoric acid (Brønsted acid), are presented. The addition of the dirhodium-bound enol to the imine yielding an α,β-diamino ester is energetically more preferred over a potentially competitive protonation of the same enol leading to an α-amino ester.

Axial coordination dichotomy in dirhodium carbenoid catalysis: a curious case of cooperative asymmetric dual-catalytic approach toward amino esters.

One of the most recent developments in asymmetric catalysis is to employ two or more catalysts under one-pot reaction conditions. This article presents some interesting mechanistic insights on a cooperative dual-catalytic protocol relying on the catalytic ability of dirhodium carbenoid (derived from rhodium(II) tetracarboxylate and a diazo compound) and a chiral spirophosphoric acid ((R)-SPA) in an asymmetric N-H insertion reaction. We have employed DFT(M06 and B3LYP) computational methods to identify the stereocontrolling transition states wherein a chiral (R)-SPA protonates a dirhodium-bound enol intermediate.

Deciphering the origin of cooperative catalysis by dirhodium acetate and chiral spiro phosphoric acid in an asymmetric amination reaction.

The mechanism of asymmetric amination of diazo-acetate by tert-butyl carbamate catalyzed by dirhodium tetra(trifluoro)acetate and chiral SPINOL-phosphoric acid is examined using DFT (M06 and B3LYP) computations. A cooperative participation of both catalysts is noticed in the stereo-controlling transition state of the reaction.

Cyclopalladation of dimesityl selenide: synthesis, reactivity, structural characterization, isolation of an intermediate complex with C-H···Pd intra-molecular interaction and computational studies.

The reaction of dimesityl selenide (Mes2Se) with either PdCl2(PhCN)2 in toluene or PdCl2 in toluene-acetonitrile yields a chloro-bridged binuclear palladium complex, [Pd2Cl2(μ-Cl)2(Mes2Se)2] (1), whereas with Na2PdCl4 in refluxing ethanol, a cyclometallated palladium complex, [Pd2(μ-Cl)2{MesSeC6H2(Me2)CH2}2] (2) is afforded. 2 can also be obtained when 1 is refluxed in ethanol. On treatment with Pb(Epy)2 in dichloromethane, 2 afforded the Epy-bridged binuclear complexes, [Pd2(μ-Epy)2{MesSeC6H2(Me2)CH2}2] (3; E = S (3a) or Se (3b)).