Tetrahydroxydiboron-Initiated Atom-Transfer Radical Cyclization

Synthesis ◽  
2021 ◽  
Author(s):  
Pengfei Wang ◽  
Yuli Li ◽  
Guangwei Wang
Keyword(s):  
Density Functional ◽  
Bond Cleavage ◽  
Radical Cyclization ◽  
Lewis Base ◽  
Atom Transfer ◽  
Functional Theory ◽  
Energy Diagram ◽  
Free Energy Diagram ◽  
Atom Transfer Radical Cyclization

In this work, the first diboron reagent initiated atom-transfer radical cyclization was reported, in which the boryl radicals were generated by the homolytic cleavage of a B-B single bond weakened by the coordination of Lewis base. To clarify the role of carbonate and DMF in the cleavage of B-B bond, we calculated the free energy diagram of two pathways by density functional theory (DFT) investigations. The DFT calculation showed that the presence of carbonate facilitates the B-B bond cleavage to form boron radicals which can be further stabilized by DMF. Subsequent atom transfer cyclization initiated by stabilized dihydroxyboron radical are also energetically favored.

scholarly journals Computational study on the mechanism of metal-free photochemical borylation of aryl halides

2021 ◽  
Author(s):  
Chenhao Tu ◽  
Nana Ma ◽  
Qingli Xu ◽  
Wenyue Guo ◽  
Lanxin Zhou ◽  
...  
Keyword(s):  
Density Functional ◽  
Uv Light ◽  
Computational Study ◽  
Halogen Bond ◽  
Bond Cleavage ◽  
Aryl Halides ◽  
Homolytic Cleavage ◽  
Functional Theory ◽  
Aryl Radicals

C-radical borylation is an significant approach for the construction of carbon−boron bond. Photochemical borylation of aryl halides successfully applied this strategy. However, precise mechanisms, such as the generation of aryl radicals and the role of base additive(TMDAM) and water, remain controversy in these reactions. In this study, photochemical borylation of aryl halides has been researched by density functional theory (DFT) calculations. Indeed, the homolytic cleavage of the C−X bond under irradiation with UV-light is a key step for generation of aryl radicals. Nevertheless, the generation of aryl radicals may also undergo the process of single electron transfer and the heterolytic carbon-halogen bond cleavage sequence, and the latter is favorable during the reaction.

On the role of the surface oxygen species during A–H (A = C, N, O) bond activation: a density functional theory study

2015 ◽  
Vol 51 (13) ◽  
pp. 2621-2624 ◽  
Author(s):  
Jong Suk Yoo ◽  
Tuhin S. Khan ◽  
Frank Abild-Pedersen ◽  
Jens K. Nørskov ◽  
Felix Studt
Keyword(s):  
Density Functional ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Oxygen Species ◽  
Final States ◽  
Surface Oxygen ◽  
Density Functional Theory Study ◽  
Reaction Energy ◽  
Functional Theory

During A–H (A = C, N, O) bond cleavage on O* or OH* pre-covered (111) surfaces, the oxygen species play the role of modifying the reaction energy by changing the species involved in the initial and final states of the reaction.

Theoretical study of NHC-catalyzed C-S bond cleavage and reconstruction reaction: Mechanism, stereoselectivity, and role of catalyst

2021 ◽  
Author(s):  
Yang Wang ◽  
Yue Liu ◽  
Kaili Gong ◽  
Han Zhang ◽  
Yu Lan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Density Functional ◽  
Theoretical Study ◽  
Bond Cleavage ◽  
Functional Theory

A theoretical study of the mechanism of the N-heterocyclic carbene (NHC)-catalyzed C-S bond cleavage and reconstruction reaction of unsaturated thioesters was conducted using density functional theory (DFT). The origin of...

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

2020 ◽  
Author(s):  
Tulin Okbinoglu ◽  
Pierre Kennepohl
Keyword(s):  
Density Functional ◽  
Chemical Properties ◽  
Functional Theory ◽  
Rotational Barriers ◽  
Td Dft ◽  
Nitrogen Bonds ◽  
X Ray Absorption ◽  
Related Compounds ◽  
And Chemical Properties

Molecules containing sulfur-nitrogen bonds, like sulfonamides, have long been of interest due to their many uses and chemical properties. Understanding the factors that cause sulfonamide reactivity is important, yet their continues to be controversy regarding the relevance of S-N π bonding in describing these species. In this paper, we use sulfur K-edge x-ray absorption spectroscopy (XAS) in conjunction with density functional theory (DFT) to explore the role of S<sub>3p</sub> contributions to π-bonding in sulfonamides, sulfinamides and sulfenamides. We explore the nature of electron distribution of the sulfur atom and its nearest neighbors and extend the scope to explore the effects on rotational barriers along the sulfur-nitrogen axis. The experimental XAS data together with TD-DFT calculations confirm that sulfonamides, and the other sulfinated amides in this series, have essentially no S-N π bonding involving S<sub>3p</sub> contributions and that electron repulsion and is the dominant force that affect rotational barriers.

Atom-transfer radical cyclization of α-bromocarboxamides under organophotocatalytic conditions

2021 ◽  
Vol 69 ◽  
pp. 152952
Author(s):  
Naoki Tsuchiya ◽  
Yusei Nakashima ◽  
Goki Hirata ◽  
Takashi Nishikata
Keyword(s):  
Radical Cyclization ◽  
Atom Transfer ◽  
Atom Transfer Radical Cyclization

γ-Valerolactone-Introduced Controlled-Isomerization of Glucose for Lactic Acid Production over Sn-Beta Catalyst

2021 ◽  
Author(s):  
Xinpeng Zhao ◽  
Zhimin Zhou ◽  
hu luo ◽  
Yanfei Zhang ◽  
Wang Liu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Lactic Acid ◽  
Dft Calculations ◽  
Acid Production ◽  
Density Functional ◽  
Lactic Acid Production ◽  
Hydrothermal Conversion ◽  
Functional Theory ◽  
Environment Friendly

Combined experiments and density functional theory (DFT) calculations provided insights into the role of the environment-friendly γ-valerolactone (GVL) as a solvent in the hydrothermal conversion of glucose into lactic acid...

scholarly journals Role of Chemistry and Crystal Structure on the Electronic Defect States in Cs-Based Halide Perovskites

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1032
Author(s):  
Anirban Naskar ◽  
Rabi Khanal ◽  
Samrat Choudhury
Keyword(s):  
Crystal Structure ◽  
Density Functional ◽  
Covalent Bond ◽  
Density Functional Theory Calculations ◽  
Antisite Defect ◽  
Defect States ◽  
Functional Theory ◽  
Electronic Defect ◽  
Constituent Elements

The electronic structure of a series perovskites ABX3 (A = Cs; B = Ca, Sr, and Ba; X = F, Cl, Br, and I) in the presence and absence of antisite defect XB were systematically investigated based on density-functional-theory calculations. Both cubic and orthorhombic perovskites were considered. It was observed that for certain perovskite compositions and crystal structure, presence of antisite point defect leads to the formation of electronic defect state(s) within the band gap. We showed that both the type of electronic defect states and their individual energy level location within the bandgap can be predicted based on easily available intrinsic properties of the constituent elements, such as the bond-dissociation energy of the B–X and X–X bond, the X–X covalent bond length, and the atomic size of halide (X) as well as structural characteristic such as B–X–B bond angle. Overall, this work provides a science-based generic principle to design the electronic states within the band structure in Cs-based perovskites in presence of point defects such as antisite defect.

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