Alkali metal hydroxide-catalyzed mechanisms of Csp-H silylation of alkynes: a DFT investigation.

Mechanisms for the Csp-H silylation between prop-2-yn-1-ylcyclohexane and triethylsilane, catalyzed by MOH/MH (M = Na or K), were investigated at the M06-L-D3/ma-def2-TZVP level. The SMD model was applied to simulate the solvent effect of 1,2-dimethoxyethane (DME). Computational results suggested that the Csp-H activation of prop-2-yn-1-ylcyclohexane could be achieved by MOH to generate R-CC-M compounds, which continued to react with triethylsilane to yield the final product: (3-cyclohexylprop-1-yn-1-yl) triethylsilane.

DFT investigation of the DDQ-catalytic mechanism for constructing C-O bonds.

In this study, we investigated the photo-catalytic mechanisms for the construction of C-O bonds from arenes (benzene, 2',6'-dimethyl-[1,1'-biphenyl]-2-carboxylic acid, or 2,4-dichloro-1-fluorobenzene), catalyzed by 2,3-dichloro-5,6-dicyano--benzoquinone (DDQ). All the structures for the Gibbs free surfaces were calculated at the M06-2X-D3/ma-def2-SVP level in the SMD solvent model. Also, TDDFT calculations of DDQ were performed at the PBE1PBE-D3/ma-def2-SVP level in the SMD solvent model.

Mechanistic Study of 1,4-Benzodiazepine-2,5-diones from Diphenylamine and Diethyl 2-Phenylmalonate by Density Functional Theory.

The mechanisms for the reaction between diphenylamine and diethyl 2-phenylmalonate were investigated using M06-2X-D3/6-31+G(d,p) method and level, and the SMD model was applied to simulate the solvent effect. The computational results suggested that diphenylamine and diethyl 2-phenylmalonate can convert into 4-hydroxy-1,3-diphenylquinolin-2(1)-one via a series of reactions (addition reaction, dealcoholization reaction, enolization reaction, dealcoholization reaction, ring-closure reaction, and H-shift reaction). And HO, as the catalyst, can play an important role to promote these reactions.

CuH-Catalyzed Asymmetric 1,6-Conjugate Reduction of -Quinone Methides: Enantioselective Synthesis of Triarylmethanes and 1,1,2-Triarylethanes.

The first copper hydride (CuH)-catalyzed asymmetric 1,6-conjugate reduction of -quinone methides is reported. This protocol provides a new method to access a variety of triarylmethanes and 1,1,2-triarylethanes in good yields with excellent enantioselectivities and broad functional group tolerance.

Linear σ-hole⋯CO⋯σ-hole intermolecular interactions between carbon monoxide and dihalogen molecules XY (X, Y=Cl, Br).

Carbon monoxide can interact with two dihalogen molecules XY (X, Y=Cl, Br) in the form of X(Y)⋯COX(Y)⋯CO⋯X(Y)X(Y) trimeric complex, and their nature and characteristics were investigated at MP2/aug-cc-pVDZ level without and with counterpoise method, together with single point calculations at CCSD(T)/aug-cc-pVDZ level. The optimized geometries, stretching modes and interaction energies of a series of X(Y)⋯COX(Y)⋯CO⋯X(Y)X(Y) trimeric complexes were obtained and discussed. The cooperativity in these complexes was evaluated.

tert-Butyl nitrite (TBN) as the N atom source for the synthesis of substituted cinnolines with 2-vinylanilines and a relevant mechanism was studied.

A green method to synthesize cinnolines by 6π electrocyclic reaction with alkenyl amines and TBN has been developed. TBN plays a dual role both as a nitrogen atom source and an oxidant in this procedure. Relevant mechanism experiments reveal that the reaction proceeds through electrocyclic reaction and with diazo hydroxide as a key intermediate.

Insights into the Diels-Alder Reaction between 3-Vinylindoles and Methyleneindolinone without and with the Assistance of Hydrogen-Bonding Catalyst Bisthiourea: Mechanism, Origin of Stereoselectivity, and Role of Catalyst.

The Diels-Alder reaction between 3-vinylindoles and methyleneindolinone can proceed both under catalyst-free conditions and with bisthiourea as the catalyst. The reaction with bisthiourea is much faster and results in higher stereoselectivity of the product. The reaction mechanism, origin of stereoselectivity, and role of the catalyst were elaborated based on quantum mechanical calculations and theoretical methods of reactivity indices, NCI, QTAIM, and distortion/interaction models.

Preparation of α-Acyloxy Ketones via Visible-Light-Driven Aerobic Oxo-Acyloxylation of Olefins with Carboxylic Acids.

We developed a visible-light driven oxo-acyloxylation of aryl alkenes with carboxylic acids and molecular oxygen. A metal-free photoredox system, consisting of an acridinium photocatalyst, an organic base, and molecular sieve (MS) 4 Å, promotes chemoselective aerobic photooxidation of aryl alkenes. This approach may provide a green, practical, and metal-free protocol for a wide range of α-acyloxy ketones.