scholarly journals Reverse Regioselectivity in Reductive Ring Opening of Epoxide Enabled by Zirconocene and Photoredox Catalysis

2021 ◽  
Author(s):  
Junichiro Yamaguchi ◽  
Eisuke Ota ◽  
Marina Hirao ◽  
Kazuhiro Aida ◽  
Aiko Funabashi ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Ring Opening ◽  
Transition States ◽  
Metallocene Catalyst ◽  
Metal Center ◽  
Photoredox Catalysis ◽  
Ring Opening Of Epoxide ◽  
Stable Radicals

A ring opening of epoxide with zirconocene and photoredox catalysis has been developed. Compared to the ring opening methods with titanocene, the present protocol exhibited reverse regioselectivity to afford more-substituted alcohols via putative less-stable radicals. DFT calculations indicated that the observed regioselectivity could be explained by shifting the transition states to more reactant-like structures by changing the metal center of the metallocene catalyst.

scholarly journals Reverse Regioselectivity in Reductive Ring Opening of Epoxide Enabled by Zirconocene and Photoredox Catalysis

2021 ◽  
Author(s):  
Junichiro Yamaguchi ◽  
Eisuke Ota ◽  
Marina Hirao ◽  
Kazuhiro Aida ◽  
Aiko Funabashi ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Ring Opening ◽  
Transition States ◽  
Metallocene Catalyst ◽  
Metal Center ◽  
Photoredox Catalysis ◽  
Ring Opening Of Epoxide ◽  
Stable Radicals

A ring opening of epoxide with zirconocene and photoredox catalysis has been developed. Compared to the ring opening methods with titanocene, the present protocol exhibited reverse regioselectivity to afford more-substituted alcohols via putative less-stable radicals. DFT calculations indicated that the observed regioselectivity could be explained by shifting the transition states to more reactant-like structures by changing the metal center of the metallocene catalyst.

Reversible Oxidative-Addition and Reductive-Elimination of Thiophene from a Titanium Complex and Its Thermally-Induced Hydrodesulfurization Chemistry

2019 ◽  
Author(s):  
Alejandra Gomez-Torres ◽  
J. Rolando Aguilar-Calderón ◽  
Carlos Saucedo ◽  
Aldo Jordan ◽  
Alejandro J. Metta-Magaña ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Ring Opening ◽  
Thiophene Ring ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Thermally Induced ◽  
Titanium Complex

<p>The masked Ti(II) synthon (<sup>Ket</sup>guan)(<i>η</i><sup>6</sup>-Im<sup>Dipp</sup>N)Ti (<b>1</b>) oxidatively adds across thiophene to give ring-opened (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti[<i>κ</i><sup>2</sup>-<i>S</i>(CH)<sub>3</sub><i>C</i>H] (<b>2</b>). Complex <b>2</b> is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate <b>1</b> – a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from <b>2</b>. Finally, pressurizing solutions of <b>2 </b>with H<sub>2</sub> (150 psi) at 80 °C leads to the hydrodesulfurization of thiophene to give the Ti(IV) sulfide (<sup>Ket</sup>guan)(Im<sup>Dipp</sup>N)Ti(S) (<b>3</b>) and butane. </p>

Mechanistic Insights into C–H Oxidations by Ruthenium(III)-Pterin Complexes: Impact of Basicity of the Pterin Ligand and Electron Acceptability of the Metal Center on the Transition States

2016 ◽  
Vol 138 (30) ◽  
pp. 9508-9520 ◽  
Author(s):  
Hiroumi Mitome ◽  
Tomoya Ishizuka ◽  
Hiroaki Kotani ◽  
Yoshihito Shiota ◽  
Kazunari Yoshizawa ◽  
...  
Keyword(s):  
Transition States ◽  
Metal Center

Key Role of π–π Complex in Diary Cross-Coupling between Aryldiazonium Salts and Arylboronic Acids using Photosensitizer-Free Gold/Photoredox Catalysis

2021 ◽  
Author(s):  
Yanhong Liu ◽  
Rong-Xiu Zhu ◽  
Chengbu Liu ◽  
Dongju Zhang
Keyword(s):  
Dft Calculations ◽  
Visible Light ◽  
Cross Coupling ◽  
Photoredox Catalysis ◽  
Arylboronic Acids ◽  
Type Complex ◽  
Free Gold ◽  
Π Complex ◽  
Td Dft

DFT and TD-DFT calculations were performed to better understand the photosensitizer-free visible-light-mediated Au-catalyzed cross-couplings between aryldiazonium salts and arylboronic acids. The π–π type complex between the aryldiazonium salt and the...

scholarly journals Synergistic catalysis: enantioselective cyclopropanation of alkylidene benzoxazoles by Pd(ii) and secondary amine catalysis. Scope, limitations and mechanistic insight

2018 ◽  
Vol 5 (5) ◽  
pp. 806-812 ◽  
Author(s):  
Marta Meazza ◽  
Victor Polo ◽  
Pedro Merino ◽  
Ramon Rios
Keyword(s):  
Dft Calculations ◽  
Secondary Amine ◽  
Ring Opening ◽  
Synergistic Catalysis ◽  
Mechanistic Insight ◽  
Amine Catalysis

An enantioselective synergistic cascade cyclopropanation/NHC catalyzed ring opening has been reported. DFT calculations have been performed to confirm the mechanism.

Active Copper Catalyzed Regioselective Ring Opening of Epoxides by Heterocyclic Amines: An Efficient Protocol for Synthesis of β-Amino Alcohols

2019 ◽  
Vol 4 (3) ◽  
pp. 194-199
Author(s):  
Santosh S. Devkate ◽  
Arvind S. Burungale ◽  
Ashok S. Pise ◽  
Sunil D. Jadhav
Keyword(s):  
Natural Products ◽  
Carbon Atom ◽  
Ring Opening ◽  
Amino Alcohols ◽  
Heterocyclic Amines ◽  
Epoxide Ring ◽  
Epoxide Ring Opening ◽  
Ring Opening Of Epoxide ◽  
Ring Opening Of Epoxides

The regioselective epoxide ring opening at less substituted carbon atom of epoxide were reported by nucleophiles like heterocyclic amines which gives well known 1,2-difunctionalized amino alcohols. These are present in many synthetic as well as natural products. The ring opening of epoxide is achieved by cleavage with amines in presence of copper(0) as a catalyst. It is observed that the lithium napthalenide reduction of copper(I) produces a highly reactive form of copper(0) that acts as a catalyst for ring opening of epoxides with an amine.

Functionalized dicyandiamide–formaldehyde polymers as efficient heterogeneous catalysts for conversion of CO2 into organic carbonates

2014 ◽  
Vol 16 (5) ◽  
pp. 2771-2778 ◽  
Author(s):  
Xiang-Lei Meng ◽  
Yi Nie ◽  
Jian Sun ◽  
Wei-Guo Cheng ◽  
Jin-Quan Wang ◽  
...  
Keyword(s):  
High Activity ◽  
Ring Opening ◽  
Heterogeneous Catalysts ◽  
Transesterification Reaction ◽  
Organic Carbonates ◽  
Ring Opening Of Epoxide

The ABMDFP exhibited high activity on cycloaddition of CO2 and transesterification reaction of EC, which was also suitable for various substrates. A possible mechanism of ring-opening of epoxide and activation of CO2 was proposed.

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