Cooperative iridium complex-catalyzed synthesis of quinoxalines, benzimidazoles and quinazolines in water

2019 ◽  
Vol 21 (8) ◽  
pp. 1999-2004 ◽  
Author(s):  
Kaushik Chakrabarti ◽  
Milan Maji ◽  
Sabuj Kundu
Keyword(s):  
Iridium Complex ◽  
Dft Studies ◽  
Metal Ligand

A sustainable protocol for the synthesis of various pharmaceutically relevant N-heterocyclic moieties was developed in water. A metal–ligand cooperative mechanism was proposed for this system based on kinetic and DFT studies.

scholarly journals Chiral-at-metal iridium complex for efficient enantioselective transfer hydrogenation of ketones

2016 ◽  
Vol 52 (22) ◽  
pp. 4207-4210 ◽  
Author(s):  
Cheng Tian ◽  
Lei Gong ◽  
Eric Meggers
Keyword(s):  
Transfer Hydrogenation ◽  
Iridium Complex ◽  
Asymmetric Transfer Hydrogenation ◽  
Metal Ligand

A pyrazole co-ligand permits a low loading iridium-catalyzed asymmetric transfer hydrogenation which is proposed to proceed through metal–ligand cooperativity.

A coordinatively unsaturated iridium complex with an unsymmetrical redox-active ligand: (spectro)electrochemical and reactivity studies

2019 ◽  
Vol 48 (37) ◽  
pp. 13931-13942 ◽  
Author(s):  
Sebastian Sobottka ◽  
Margarethe Behr van der Meer ◽  
Estelle Glais ◽  
Uta Albold ◽  
Simon Suhr ◽  
...  
Keyword(s):  
Bond Activation ◽  
Iridium Complex ◽  
Iridium Complexes ◽  
Redox Active Ligand ◽  
Active Ligand ◽  
Redox Active ◽  
Metal Ligand

Metal–ligand cooperativity can be used in iridium complexes with an unsymmetrically substituted redox-active diamidobenzene ligand for bond activation reactions.

The N-alkylation of sulfonamides with alcohols in water catalyzed by a water-soluble metal–ligand bifunctional iridium complex [Cp*Ir(biimH2)(H2O)][OTf]2

2019 ◽  
Vol 43 (27) ◽  
pp. 10755-10762 ◽  
Author(s):  
Yao Ai ◽  
Pengcheng Liu ◽  
Ran Liang ◽  
Yan Liu ◽  
Feng Li
Keyword(s):  
Water Soluble ◽  
Iridium Complex ◽  
Effective Catalyst ◽  
Bridging Ligand ◽  
Highly Effective ◽  
Metal Ligand

A water-soluble dinuclear Cp*Ir complex bearing 4,4′,6,6′-tetrahydroxy-2,2′-bipyrimidine as a bridging ligand was found to be a highly effective catalyst for the N-alkylation of ketones with alcohols in water.

The Reaction of (PPri3)2H2Cl2Ir With Phosphines: Crystal and Molecular Structures of mer-cis-(PMe2Ph)2(PPri3)-cis-Cl2HIrIII and mer-cis-(PMe2Ph)2(PPri3)-trans-Cl2HIrIII

1993 ◽  
Vol 46 (4) ◽  
pp. 529 ◽  
Author(s):  
EJ Ditzel ◽  
GB Robertson
Keyword(s):  
Phosphine Ligands ◽  
Molecular Structures ◽  
Iridium Complex ◽  
Steric Strain ◽  
Distorted Octahedral Coordination ◽  
Crystal And Molecular Structures ◽  
Distorted Octahedral ◽  
Spontaneous Reaction ◽  
Summary Data ◽  
Metal Ligand

Ambient temperature reactions of the complex (PPri3)2H2Cl2IrIV (1) with ethyl-substituted monodentate phosphine ligands are shown to yield different product types to those obtained both with methyl-substituted analogues and with phosphine itself. With the phosphines PH3 and PMe3-nPhn (n = 0, 1) there is spontaneous reaction to give the complexes mer-trans-(Ppri3)2(PR3)H-trans-Cl2IrIII, whereas with PEt3-nPhn (n = 0-2) the reaction yields mer-cis-(PR3)2(PPri3)H-trans-Cl2IrIII complexes. Under reflux the phosphines PMe3 and PMe2Ph also yield mer-cis-(PR3)2(PPri3)H-trans-Cl2IrIII complexes [PR3 = PMe3 (2), Pme2Ph (3)]. The differing course of the reactions of (1) with PMe3 and with PEt3 has permitted the synthesis of mer-(Pme3)-trans-(PPri3)(PEt3)H-trans-Cl2IrIII, the first example of an octahedral iridium complex containing three different monodentate phosphine ligands. All of the products obtained have been fully characterized by 31P and 1H n.m.r. spectroscopy. Crystal structure analyses of (3) and of its photoisomer mer-cis-(PMe2Ph)2(PPri3)H-cis-Cl2IrIII (4) have been carried out to permit comparison of the metal-ligand bonding in these complexes with that in their previously characterized, sterically less crowded, tris-PMe2Ph analogues. Summary data are as follows: (3), triclinic, Pī, a 13.414(1), b 12.062(1), c 9.077(1) Ǻ, α 79.53(1), β 88.05(1), γ 79.47(1)° [T 158�3 K], Z 2, R 0.022, Rw 0.032 (4822 reflections); (4), monoclinic, P21/n, a 19.694(1), b 15.972(1), c 9.548(1) Ǻ, β 101.45(1)° (T 293�2 K), Z 4, R 0.026, Rw 0.032 (5476 reflections). Both molecules exhibit distorted octahedral coordination of the metal atom and appreciably greater steric strain than in their (Pme2Ph)3HCl2IrIII analogues. Metal-ligand distances to the mutually trans Pme2Ph and PPri3 ligands are 2.322(1) and 2.372(1)Ǻ, respectively, for (3), and 2.359(1) and 2.406(1)Ǻ for (4), and suggest that the thermodynamically favoured cis-dichloro isomer (4) is the more strained. The preparations of the complexes (PCy3)2H2Cl2IrIV (1a) and (PCy3)2H2Br2IrIV (1b) (Cy = cyclohexyl), and their reactions with the same phosphines as used with (1), are also reported.

Stereodivergent Alkyne Hydrofluorination Using a Simple Practical Reagent

2020 ◽  
Author(s):  
Rui Guo ◽  
Xiaotian Qi ◽  
Hengye Xiang ◽  
Paul Geaneoates ◽  
Ruihan Wang ◽  
...  
Keyword(s):  
Bond Formation ◽  
Biologically Active ◽  
Dft Studies ◽  
Thermodynamic Control ◽  
Important Goal ◽  
Peptide Bonds ◽  
Metal Free ◽  
Vinyl Cation ◽  
E And Z Isomers ◽  
Vinyl Fluorides

Vinyl fluorides play an important role in drug development as they serve as bioisosteres for peptide bonds and are found in a range of biologically active molecules. The discovery of safe, general and practical procedures to prepare vinyl fluorides remains an important goal and challenge for synthetic chemistry. Here we introduce an inexpensive and easily-handled reagent and report simple, scalable, and metal-free protocols for the regioselective and stereodivergent hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These conditions were suitable for a diverse collection of alkynes, including several highly-functionalized pharmaceutical derivatives. Mechanistic and DFT studies support C–F bond formation through a vinyl cation intermediate, with the (E)- and (Z)-hydrofluorination products forming under kinetic and thermodynamic control, respectively.<br>

Copper Catalyzed sp3 C-H α-Acetylation

2019 ◽  
Author(s):  
Otome Okoromoba ◽  
Eun Sil Jang ◽  
Claire McMullin ◽  
Thomas Cundari ◽  
Timothy H. Warren
Keyword(s):  
Natural Products ◽  
Dft Studies ◽  
Alkyl Radicals ◽  
Important Chemical ◽  
Alkyl Electrophiles ◽  
Synthetic Intermediates ◽  
Alkylation Reactions

<p>α-substituted ketones are important chemical targets as synthetic intermediates as well as functionalities in in natural products and pharmaceuticals. We report the sp<sup>3</sup> C-H α-acetylation of sp<sup>3</sup> C-H substrates R-H with arylmethyl ketones ArC(O)Me to provide α-alkylated ketones ArC(O)CH<sub>2</sub>R at RT with <sup>t</sup>BuOO<sup>t</sup>Bu as oxidant via copper(I) β-diketiminato catalysts. Proceeding via alkyl radicals R•, this method enables α-substitution with bulky substituents without competing elimination that occurs in more traditional alkylation reactions between enolates and alkyl electrophiles. DFT studies suggest the intermediacy of copper(II) enolates [Cu<sup>II</sup>](CH<sub>2</sub>C(O)Ar) that capture alkyl radicals R• to give R-CH<sub>2</sub>C(O)Ar under competing dimerization of the copper(II) enolate to give the 1,4-diketone ArC(O)CH<sub>2</sub>CH<sub>2</sub>C(O)Ar.</p>

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