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Gold allenylidene species have been seldom exploited as reactive intermediates in synthetically versatile catalytic reactions. By employing alkynylbenziodoxoles as the substrates and bifunctional WangPhos as the metal ligand, this work demonstrated ready catalytic access to these intermediates of general substitution patterns and their electrophilic reactivities at the γ‐carbon center with a diverse range of nucleophiles. The reaction is driven by the reductive decomposition of the benziodoxole moiety and achieves the replacement of a propargylic proton with an N/O/C‐based nucleophile, hence realizing reactivity umpolung. Corroborated by Density Functional Theory (DFT) calculations, the reaction mechanism involves a mild propargylic deprotonation. In contrast to prior works employing a tertiary amine functionality, a weakly BrØnsted‐basic amide group in WangPhos is surprisingly effective in deprotonation at the propargylic position under a gold‐ligand cooperation regime. [ABSTRACT FROM AUTHOR]

The quantitative Lewis acidity of N‐heterocyclic iod(az)olium salts is helpful for their further application in organic chemistry. The acidity scales of different N‐Heterocyclic iodonium salts (NHISs) in acetonitrile are investigated using Density functional theory (DFT) studies. There are a total of 121N‐Heterocyclic iodonium salts that have been designed by combining N‐heterocyclic and iodonium salt structures in this research. Theoretical calculations systematically established the 31P NMR chemical shifts of NHISs, and the relative Lewis acidity scale was derived. The Lewis acidity trend is analyzed and explained by the natural population analysis (NPA) charges, molecular electrostatic potential, and the interaction between the iodonium center and the N‐heterocyclic substituents. This study is expected to provide a practical quantitative theoretical scale for the understanding and design of hypervalent iodine(III) reagents with versatile Lewis acidity. [ABSTRACT FROM AUTHOR]

The optical isomerization of amphoteric S-α-Ala·Na+ in water-liquid phase environment was investigated by using the M06-2X method based on density functional theory and the SMD model method based on self consistent reaction field (SCRF) theory. The results showed that the optical isomerization of S-α-Ala·Na+ has three channels a,b and c. In channel a, the proton transfers with amino nitrogen as a bridge after the isomerization of amphoteric S-α-Ala·Na+ to neutral S-α-Ala·Na+. And the proton is transferred merely using carbonyl oxygen as a bridge in channel b. In channel c, the proton transfers to α-C from protonation amino after α-H is transferred to carbonyl oxygen. The potential energy surface showed that the channel a has the most advantage under the effect of recessive solvent and the energy barrier of the rate-determining step is 234. 8 kJ·mol-1; While channel b and c had a disadvantage, they both have the common energy barrier of the rate-determining step about 267. 9 kJ·mol-1. Under the effect of explicit solvent, channel a turned to an inferior channel, and its energy barrier of the rate-determining step is between 155. 9 and 156. 5 kJ·mol-1; channel b and c have a slight advantage and the energy barrier of the rate-determining step is between 132.2 and 138.6 kJ·mol-1. The results showed that α-alanineNa (I) complex could only racemize at a extremely slow speed in the water-liquid environment. [ABSTRACT FROM AUTHOR]

Sila-molecules have recently attracted attention due to their promising applications in medical and industrial fields. Compared with all-carbon parent compounds, the different covalent radius and electronegativity of silicon from carbon generally endow the corresponding sila-analogs with unique biological activity and physicochemical properties. Vinylsilanes feature both silyl-hyperconjugation effect and versatile reactivities, developing vinylsilane-based Smiles rearrangement will therefore provide an efficient platform to assemble complex silacycles. Here we report a practical Ir(III)-catalyzed cycloaromatization of ortho-alkynylaryl vinylsilanes with arylsulfonyl azides for delivering naphthyl-fused benzosiloles under visible-light photoredox conditions. The combination of experiments and density functional theory (DFT) energy profiles reveals the reaction mechanism involving α-silyl radical Smiles rearrangement. Arene-fused siloles have attracted interest due to their promising applications in electronic and optoelectronic devices. Here, the authors report Ir(III)-catalyzed cycloaromatization of ortho-alkynylaryl vinylsilanes with arylsulfonyl azides via α-silyl radical Smiles rearrangement for accessing naphthyl-fused benzosiloles under visible-light photoredox conditions. [ABSTRACT FROM AUTHOR]

For the first time, a highly regioselective intermolecular sulfonylamidation unactivated secondary Csp3−H bond has been achieved using IrIII catalysts. The introduced N, N'-bichelating ligand plays a crucial role in enabling iridium-nitrene insertion into a secondary Csp3−H bond via an outer-sphere pathway. Mechanistic studies and density functional theory (DFT) calculations demonstrated that a two-electron concerted nitrene insertion was involved in this Csp3−H amidation process. This method tolerates a broad range of linear and branched-chain N-alkylamides, and provides efficient access to diverse γ-sulfonamido-substituted aliphatic amines. [ABSTRACT FROM AUTHOR]

Dithiolene-based complexes show great potential to be applied as materials for organic optoelectronic devices. In this study, we theoretically designed a series of complexes based on nickel dithiolene and its substituted derivatives, the optoelectronic properties of which were comparatively studied by density functional theory (DFT)/time-dependent density functional theory (TD-DFT). The results show that the charge injection property of nickel dithiolene complexes can be significantly improved with introduction of electron-withdrawing groups. The charge transportation property of nickel dithiolene depends on the conjugation degree of the system. The energy gaps between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are determined by the substituents, which makes the maximum absorption wavelength red-shift from the visible to the near-infrared (NIR) region. The electron density difference graph shows that the electron transition from the ground state to the first excited state is assigned to π-π* transition mainly from HOMO to LUMO. The regularity of substituent effect revealed by us in this study will shed light on the application of nickel dithiolenes as potential optoelectronic materials. [ABSTRACT FROM AUTHOR]

• Clarifying the role of coordination structure of the active site for the asymmetric hydrogenation. • Elucidating the influence of excess base in reaction for metal ligand cooperation. • Revealing the importance of steric effect between reactant and catalyst in the asymmetric hydrogenation. The asymmetric hydrogenation of 3H-indole is highly important for the synthesis of chiral indole as potential biologically active products and drugs. To better understand the mechanism and the origin of enantioselectivity for PNN-Mn-catalyzed asymmetric hydrogenation of 3H-indole, density functional theory studies were performed to study the influence of the coordination geometry and the deprotonation by additive base on the reaction. Our results revealed that the coordination structure of the active species adopts the fac- geometry rather than the mer- geometry. The excess additive base is crucial for the deprotonation of the pre-catalyst. The most plausible active species should be doubly deprotonated at the amine site and the imidazole site. The comparison of detailed potential energy surfaces for possible active species at different deprotonation situations suggests that the hydride transfer from the metal hydride to the reactant is the key step for the asymmetric reaction, in which the R -configuration transition state is found to be preferred over the S -configuration one(yielding a theoretical ee value of 98.5 %), in good agreement with the experimental results(97 % ee). Noncovalent interaction analysis of the key transition states found that the steric effect during hydride transfer plays an important role in enantioselectivity. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium carbenoids are important reagents in organic synthesis. Systemic DFT calculations have been carried out to reveal the influence of hetero-aggregation states on the reactivity of lithium carbenoid reagents. The results indicate that the cyclopropanation reaction could be accelerated dramatically by hetero-aggregated lithium carbenoids with a halogen or oxygen as an α-heteroatom. The origin of the enhancement could attribute to the novel structural character of the hetero-aggregated lithium carbenoids. These intriguing finding predicts that it is practical to control a wide range of S N 2-type organometallic reactions by using aggregated lithium carbenoids with other economical and convenient compounds. [ABSTRACT FROM AUTHOR]