Well-defined nickel(II) tetrazole-saccharinate complex as homogeneous catalyst on the reduction of aldehydes: scope and reaction mechanism

2020 ◽  
Vol 92 (1) ◽  
pp. 151-166 ◽  
Author(s):  
Luís M. T. Frija ◽  
Bruno G. M. Rocha ◽  
Maxim L. Kuznetsov ◽  
Lília I. L. Cabral ◽  
M. Lurdes S. Cristiano ◽  
...  
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Transition Metal ◽  
Dft Calculations ◽  
Microwave Power ◽  
Low Temperatures ◽  
Nickel Complex ◽  
Transition Metal Catalysts ◽  
Homogeneous Catalyst ◽  
First Time

AbstractA new (tetrazole-saccharin)nickel complex is shown to be a valuable catalyst for the hydrosilative reduction of aldehydes under microwave radiation at low temperatures. With typical 1 mol% content of the catalyst (microwave power range of 5–15 W) most reactions are complete within 30 min. The Ni(II)-catalyzed reduction of aldehydes, with a useful scope, was established for the first time by using this catalyst, and is competitive with the most effective transition-metal catalysts known for such transformation. The catalyst reveals tolerance to different functional groups, is air and moisture stable, and is readily prepared in straightforward synthetic steps. Supported by experimental data and DFT calculations, a plausible reaction mechanism involving the new catalytic system is outlined.

Cu(I)-Bis(phosphine) Dioxides as catalysts for the Enantioselective α-Arylation of Carbonyl Compounds

Synlett ◽  
2021 ◽  
Author(s):  
Margarita Escudero-Casao ◽  
Giulia Licini ◽  
Manuel Orlandi
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal ◽  
Catalytic System ◽  
Carbonyl Compounds ◽  
Research Area ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

The transition metal catalyzed α-arylation of carbonyl compounds was first reported by Buchwald and Hartwig in 1997. This transformation has been used and studied extensively over the last two decades. Enantioselective variants were also developed that allow for controlling the product stereochemistry. However, these suffer several limitations in the context of formation of tertiary stereocenters. Presented here is our group’s contribution to this research area. The chiral Cu-bis(phosphine) dioxides catalytic system that we reported allowed accessing the enantioselective α-arylation of ketones that were not suitable for this transformation before in good yields and er up to 97.5:2.5. Preliminary insight and speculation concerning the reaction mechanism involving the unusual pairing of bis(phosphine) dioxides with transition metal catalysts is also given.

Epoxide Migration and Pseudo-Epoxide Migration of 1,6:2,3- and 1,6:3,4-Dianhydro-β-D-hexopyranoses. Synthesis of Some Deoxy Halo Derivatives of 1,6-Anhydro-β-D-hexopyranoses

2006 ◽  
Vol 71 (10) ◽  
pp. 1497-1515 ◽  
Author(s):  
Martina Džoganová ◽  
Miloslav Černý ◽  
Miloš Buděšínský ◽  
Martin Dračínský ◽  
Tomáš Trnka
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Dft Calculations ◽  
Sodium Hydroxide ◽  
Sodium Iodide ◽  
Aqueous Sodium Hydroxide ◽  
Aqueous Sodium ◽  
Derivatives Of

Epoxide or pseudo-epoxide migration of 1,6:2,3-dianhydro- and 1,6:3,4-dianhydro-β-D-hexopyranoses was effected by treatment with aqueous sodium hydroxide or sodium iodide in acetone to give equilibrium mixtures. Various iodo derivatives of 1,6-anhydro-β-D-hexopyranoses were prepared as potential intermediates for pseudo-epoxide migration. NMR was used for following the reaction mechanism of epoxide and pseudo-epoxide migrations and analysis of reaction mixtures. Experimental data were compared with DFT calculations. Chair-boat equilibration of 1,6-anhydro-3-deoxy-3-halo-β-D-glucopyranoses was discussed.

NH3 oxidation to nitrogen and water at low temperatures using supported transition metal catalysts

2000 ◽  
Vol 61 (1-4) ◽  
pp. 179-185 ◽  
Author(s):  
Lu Gang ◽  
B.G Anderson ◽  
J van Grondelle ◽  
R.A van Santen
Keyword(s):  
Transition Metal ◽  
Low Temperatures ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Nh3 Oxidation

scholarly journals Divergent Rhodium-Catalyzed Electrochemical Vinylic C–H Annulation of Acrylamides with Alkynes

2020 ◽  
Author(s):  
Yi-Kang Xing ◽  
Xin-Ran Chen ◽  
Qi-Liang Yang ◽  
Shuoqing Zhang ◽  
Haiming Guo ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal ◽  
Dft Calculations ◽  
Reductive Elimination ◽  
Electrochemical Process ◽  
Membered Ring ◽  
Environmentally Benign ◽  
Rhodium Catalysis ◽  
Undivided Cell ◽  
Metal Catalyzed

Abstract A Rh-catalyzed electrochemical vinylic C–H annulation of acrylamides with alkynes has been developed in an undivided cell, affording cyclic products in good to excellent yield. Divergent syntheses of α-pyridones and cyclic imidates are accomplished by employing N-phenyl acrylamides and N-tosyl acrylamides as substrates, respectively. Additionally, excellent regioselectivities are achieved when using unsymmetrical alkynes. This electrochemical process is environmentally benign compared to traditional transition metal-catalyzed C–H annulations because it avoids the use of stoichiometric metal oxidants. DFT calculations elucidated the reaction mechanism and origins of substituent-controlled chemoselectivity. The sequential C–H activation and alkyne insertion under rhodium catalysis leads to the seven-membered ring vinyl-rhodium intermediate. This intermediate undergoes either the classic neutral concerted reductive elimination to produce α-pyridones, or the ionic stepwise pathway to produce cyclic imidates.

Microwave-assisted Cobalt-copper Dual Catalyzed Ligand Free C-Se Cross-coupling

2020 ◽  
Vol 7 (2) ◽  
pp. 157-163
Author(s):  
Debasish Kundu ◽  
Anup Roy ◽  
Subir Panja ◽  
Raj K. Singh
Keyword(s):  
Transition Metal ◽  
Cross Coupling ◽  
Building Blocks ◽  
Transition Metal Catalysts ◽  
Metal Catalyst ◽  
Co Catalyst ◽  
Ligand Free ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed ◽  
First Time

Background: Organoselenides are important building blocks of several biologically important molecules and natural products. Several protocols have been developed by chemists for their synthesis. Transition metal-catalyzed cross-coupling is a powerful tool for this purpose in the last two decades. Various transition metal catalysts e.g. Pd, Ni, Cu, In etc. have been used for performing C-Se cross-coupling in the presence or absence of ligands. Objective: Development of a sustainable protocol for transition metal-catalyzed C-Se cross-coupling is the main objective of this research. Recently, Cobalt has been applied as a cheap and sustainable transition metal catalyst in several organic reactions. This protocol is focused on applying cobalt salt as a catalyst for performing C-Se cross-coupling for the first time. Methods: Co(acac)2 has been successfully employed for performing Se-arylations in the presence of CuI, which acts as a co-catalyst under microwave irradiation. NMP was used as solvent and KOH as a reductant in this reaction. Results: Both iodo-and bromoarenes have been used to perform C-Se cross-coupling with diaryl diselenide under this Co/Cu dual catalytic system. The reaction was successful with both electrondonating and withdrawing groups in ortho-, meta-, and para-positions in the aromatic ring of Bromo and iodoarenes. Conclusion: This is an effective protocol for the preparation of organoselenides, catalyzed by cobalt in the presence of copper. The mechanism has been established by several experimental techniques.

The reaction mechanism in the ethanolysis of urea with transition metal-based catalysts: DFT calculations and experiments

2014 ◽  
Vol 8 ◽  
pp. 27-33 ◽  
Author(s):  
Angela Dibenedetto ◽  
Antonella Angelini ◽  
Stefania Fasciano ◽  
Imre Pàpai ◽  
Daniel Curulla-Ferré ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal ◽  
Dft Calculations

Thermo-regulated phase separable catalysis (TPSC)-based atom transfer radical polymerization in a thermo-regulated ionic liquid

2014 ◽  
Vol 50 (66) ◽  
pp. 9266-9269 ◽  
Author(s):  
Xiangyang Du ◽  
Jinlong Pan ◽  
Mengting Chen ◽  
Lifen Zhang ◽  
Zhenping Cheng ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Catalytic Activity ◽  
Transition Metal ◽  
Atom Transfer Radical Polymerization ◽  
Radical Polymerization ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Atom Transfer ◽  
Aget Atrp ◽  
First Time

A thermo-regulated phase separable catalysis (TPSC) system for AGET ATRP based on a thermo-regulated ionic liquid was developed for the first time. The corresponding transition metal catalysts could be easily recovered and reused several times with negligible loss of catalytic activity.

scholarly journals Focusing on the Catalysts of the Pd- and Ni-Catalyzed Hirao Reactions

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3897
Author(s):  
György Keglevich ◽  
Réka Henyecz ◽  
Zoltán Mucsi
Keyword(s):  
Experimental Data ◽  
Transition Metal ◽  
Ligand Exchange ◽  
Theoretical Calculations ◽  
Reductive Elimination ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Aryl Halides ◽  
Feature Article ◽  
Bond Forming

The Hirao reaction involving the phosphinoylation or phosphonation of aryl halides by >P(O)H reagents is a P–C bond forming transformation belonging to the recently very hot topic of cross-couplings. The Pd- or Ni-catalyzed variations take place via the usual cycle including oxidative addition, ligand exchange, and reductive elimination. However, according to the literature, the nature of the transition metal catalysts is not unambiguous. In this feature article, the catalysts described for the Pd(OAc)2-promoted cases are summarized, and it is concluded that the “(HOY2P)2Pd(0)” species (Y = aryl, alkoxy) is the real catalyst. In our model, the excess of the >P(O)H reagent served as the P-ligand. During the less studied Ni(II)-catalyzed instances the “(HOY2P)(−OY2P)Ni(II)Cl−” form was found to enter the catalytic cycle. The newest conclusions involving the exact structure of the catalysts, and the mechanism for their formation explored by us were supported by our earlier experimental data and theoretical calculations.

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