scholarly journals Asymmetric Hydrogenation of 1-aryl substituted-3,4-Dihydroisoquinolines with Iridium Catalysts Bearing Different Phosphorus-Based Ligands

Catalysts ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 914
Author(s):  
Giorgio Facchetti ◽  
Michael S. Christodoulou ◽  
Eleonora Binda ◽  
Marco Fusè ◽  
Isabella Rimoldi
Keyword(s):  
Asymmetric Hydrogenation ◽  
Catalytic Performance ◽  
Phosphine Ligand ◽  
Iridium Complexes ◽  
Complete Conversion ◽  
Catalytic Systems ◽  
Iridium Catalysts ◽  
Substituted 1

Starting from the chiral 5,6,7,8-tetrahydroquinolin-8-ol core, a series of amino-phosphorus-based ligands was realized. The so-obtained amino-phosphine ligand (L1), amino-phosphinite (L2) and amino-phosphite (L3) were evaluated in iridium complexes together with the heterobiaryl diphosphines tetraMe-BITIOP (L4), Diophep (L5) and L6 and L7 ligands, characterized by mixed chirality. Their catalytic performance in the asymmetric hydrogenation (AH) of the model substrate 6,7-dimethoxy-1-phenyl-3,4-dihydroisoquinoline 1a led us to identify Ir-L4 and Ir-L5 catalysts as the most effective. The application of these catalytic systems to a library of differently substituted 1-aryl-3,4-dihydroisoquinolines afforded the corresponding products with variable enantioselective levels. The 4-nitrophenyl derivative 3b was obtained in a complete conversion and with an excellent 94% e.e. using Ir-L4, and a good 76% e.e. was achieved in the reduction of 2-nitrophenyl derivative 6a using Ir-L5.

Temperature-Controlled Bidirectional Enantioselectivity in Asymmetric Hydrogenation Reactions Utilizing Stereodynamic Iridium Complexes

Synthesis ◽  
2017 ◽  
Vol 49 (15) ◽  
pp. 3485-3494 ◽  
Author(s):  
Max Siebert ◽  
Golo Storch ◽  
Frank Rominger ◽  
Oliver Trapp
Keyword(s):  
Elevated Temperatures ◽  
Asymmetric Hydrogenation ◽  
Iridium Complexes ◽  
Chirality Transfer ◽  
Iridium Catalysts ◽  
Thermal Equilibration ◽  
Hydrogenation Reactions ◽  
Temperature Controlled ◽  
First Time ◽  
Solid State Structures

Stereochemically flexible 2,2(-bis(diphenylphosphino)biphenyl (BIPHEP) ligands were modified with chiral α-substituted carboxylic acid auxiliaries in the 3- and 3′-position. The resulting central-to-axial chirality transfer to the stereochemically flexible chiral axis of the BIPHEP­ core was investigated as well as complexation of these diastereomeric ligands to iridium(I). Solid-state structures of both ligand diastereomers and a diastereomerically pure iridium(I) BIPHEP complex were obtained. Thermal equilibration of the resulting iridium(I) complexes was studied to investigate the stereodynamic properties of the BIPHEP ligands. The iridium(I) complexes without and after pre-catalysis warming in solution — which induces a shift of the diastereomeric ratio — were applied for asymmetric hydrogenation of a prochiral α-substituted acrylic acid, resulting in temperature-controlled bidirectional enantioselectivity of iridium catalysts for the first time. In both cases, enantioenriched (R)-naproxen as well as (S)-naproxen — after re-equilibration of the catalyst at elevated temperatures — was obtained by using the same catalyst.

Progress on Iridium-Catalyzed Hydrosilylation of Alkenes and Alkynes

Synthesis ◽  
2020 ◽  
Vol 52 (23) ◽  
pp. 3549-3563
Author(s):  
Shengtao Ding ◽  
Weiwei Gao
Keyword(s):  
Precious Metal ◽  
Platinum Complexes ◽  
Short Review ◽  
Iridium Complexes ◽  
Organosilicon Compounds ◽  
Catalytic Systems ◽  
Iridium Catalysts ◽  
Recent Advances ◽  
Precious Metal Catalysts ◽  
Carbon Carbon Bonds

Hydrosilylation of multiple carbon–carbon bonds is a well-known process for the construction of organosilicon compounds. Nowadays, precious metal catalysts, especially platinum complexes, still occupy dominant positions in such processes. However, one important member of the precious metal family, iridium, is less used in this field. As early research mainly focused on developing stable and effective iridium catalysts, recent advances have disclosed the specific efficiency of simple iridium catalytic systems in the synthesis of functional organo­silicon compounds. This short review summarizes the utilization of iridium complexes for the hydrosilylation of alkenes and alkynes, with an emphasis on the recent advances published in the last decade.1 Introduction2 Iridium-Catalyzed Hydrosilylation of Alkenes3 Iridium-Catalyzed Hydrosilylation of Alkynes4 Conclusions and Perspectives

Recent Developments in Transition-Metal-Catalyzed Asymmetric Hydrogenation of Enamides

Synthesis ◽  
2020 ◽  
Vol 53 (02) ◽  
pp. 193-214
Author(s):  
Phannarath Phansavath ◽  
Virginie Ratovelomanana-Vidal ◽  
Sudipta Ponra ◽  
Bernard Boudet
Keyword(s):  
Academic Research ◽  
Asymmetric Hydrogenation ◽  
Nickel Catalysts ◽  
Industrial Applications ◽  
Ruthenium Catalysts ◽  
Cobalt Catalysts ◽  
Rhodium Catalysts ◽  
Catalytic Systems ◽  
Iridium Catalysts ◽  
Metal Catalyzed

AbstractThe catalytic asymmetric hydrogenation of prochiral olefins is one of the most widely studied and utilized transformations in asymmetric synthesis. This straightforward, atom economical, inherently direct and sustainable strategy induces chirality in a broad range of substrates and is widely relevant for both industrial applications and academic research. In addition, the asymmetric hydrogenation of enamides has been widely used for the synthesis of chiral amines and their derivatives. In this review, we summarize the recent work in this field, focusing on the development of new catalytic systems and on the extension of these asymmetric reductions to new classes of enamides.1 Introduction2 Asymmetric Hydrogenation of Trisubstituted Enamides2.1 Ruthenium Catalysts2.2 Rhodium Catalysts2.3 Iridium Catalysts2.4 Nickel Catalysts2.5 Cobalt Catalysts3 Asymmetric Hydrogenation of Tetrasubstituted Enamides3.1 Ruthenium Catalysts3.2 Rhodium Catalysts3.3 Nickel Catalysts4 Asymmetric Hydrogenation of Terminal Enamides4.1 Rhodium Catalysts4.2 Cobalt Catalysts5 Rhodium-Catalyzed Asymmetric Hydrogenation of Miscellaneous Enamides6 Conclusions

Efficient and Versatile Catalytic Systems for the N-Methylation of Primary Amines with Methanol Catalyzed by N-Heterocyclic Carbene Complexes of Iridium

Synthesis ◽  
2018 ◽  
Vol 50 (23) ◽  
pp. 4617-4626 ◽  
Author(s):  
Ken-ichi Fujita ◽  
Genki Toyooka ◽  
Akiko Tuji
Keyword(s):  
Low Temperatures ◽  
Aromatic Amines ◽  
Catalytic Performance ◽  
Aliphatic Amines ◽  
Primary Amines ◽  
Iridium Complexes ◽  
Reaction Conditions ◽  
Catalytic Systems ◽  
Carbene Complexes ◽  
Amine Compounds

Efficient and versatile catalytic systems were developed for the N-methylation of both aliphatic and aromatic primary amines using methanol as the methylating agent. Iridium complexes bearing an N-heterocyclic carbene (NHC) ligand exhibited high catalytic performance for this type of transformation. For aliphatic amines, selective N,N-dimethylation was achieved at low temperatures (50–90 °C). For aromatic amines, selective N-monomethylation and selective N,N-dimethylation were accomplished by simply changing the reaction conditions (presence or absence of a base with an appropriate catalyst). These findings can be used to develop methods for synthesizing useful amine compounds having N-methyl or N,N-dimethyl moieties.

ChemInform Abstract: Chiral Iridium Catalysts Bearing Spiro Pyridine-Aminophosphine Ligands Enable Highly Efficient Asymmetric Hydrogenation of β-Aryl β-Ketoesters.

ChemInform ◽  
2012 ◽  
Vol 43 (20) ◽  
pp. no-no
Author(s):  
Jian-Hua Xie ◽  
Xiao-Yan Liu ◽  
Xiao-Hui Yang ◽  
Jian-Bo Xie ◽  
Li-Xin Wang ◽  
...  
Keyword(s):  
Asymmetric Hydrogenation ◽  
Iridium Catalysts ◽  
Highly Efficient

ChemInform Abstract: Iridium Catalysts with Chiral Imidazole-Phosphine Ligands for Asymmetric Hydrogenation of Vinyl Fluorides and other Olefins.

ChemInform ◽  
2008 ◽  
Vol 39 (39) ◽  
Author(s):  
Paeivi Kaukoranta ◽  
Mattias Engman ◽  
Christian Hedberg ◽  
Jonas Bergquist ◽  
Pher G. Andersson
Keyword(s):  
Asymmetric Hydrogenation ◽  
Phosphine Ligands ◽  
Iridium Catalysts ◽  
Vinyl Fluorides

Iridium Complexes with Phosphine−Phosphite Ligands. Structural Aspects and Application in the Catalytic Asymmetric Hydrogenation of N-Aryl Imines

2006 ◽  
Vol 25 (4) ◽  
pp. 961-973 ◽  
Author(s):  
Sergio Vargas ◽  
Miguel Rubio ◽  
Andrés Suárez ◽  
Diego del Río ◽  
Eleuterio Álvarez ◽  
...  
Keyword(s):  
Asymmetric Hydrogenation ◽  
Iridium Complexes ◽  
Phosphite Ligands ◽  
Catalytic Asymmetric ◽  
Catalytic Asymmetric Hydrogenation ◽  
Structural Aspects

scholarly journals Enhanced Photocatalytic Activity and Stability in Hydrogen Evolution of Mo6 Iodide Clusters Supported on Graphene Oxide

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1259
Author(s):  
Marta Puche ◽  
Rocío García-Aboal ◽  
Maxim A. Mikhaylov ◽  
Maxim N. Sokolov ◽  
Pedro Atienzar ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Gas Phase ◽  
Hybrid Material ◽  
Liquid Water ◽  
Catalytic Performance ◽  
H2 Production ◽  
Cluster Compound ◽  
Catalytic Systems ◽  
Active Cluster ◽  
First Time

Catalytic properties of the cluster compound (TBA)2[Mo6Ii8(O2CCH3)a6] (TBA = tetrabutylammonium) and a new hybrid material (TBA)2Mo6Ii8@GO (GO = graphene oxide) in water photoreduction into molecular hydrogen were investigated. New hybrid material (TBA)2Mo6Ii8@GO was prepared by coordinative immobilization of the (TBA)2[Mo6Ii8(O2CCH3)a6] onto GO sheets and characterized by spectroscopic, analytical, and morphological techniques. Liquid and, for the first time, gas phase conditions were chosen for catalytic experiments under UV–Vis irradiation. In liquid water, optimal H2 production yields were obtained after using (TBA)2[Mo6Ii8(O2CCH3)a6] and (TBA)2Mo6Ii8@GO) catalysts after 5 h of irradiation of liquid water. Despite these remarkable catalytic performances, “liquid-phase” catalytic systems have serious drawbacks: the cluster anion evolves to less active cluster species with partial hydrolytic decomposition, and the nanocomposite completely decays in the process. Vapor water photoreduction showed lower catalytic performance but offers more advantages in terms of cluster stability, even after longer radiation exposure times and recyclability of both catalysts. The turnover frequency (TOF) of (TBA)2Mo6Ii8@GO is three times higher than that of the microcrystalline (TBA)2[Mo6Ii8(O2CCH3)a6], in agreement with the better accessibility of catalytic cluster sites for water molecules in the gas phase. This bodes well for the possibility of creating {Mo6I8}4+-based materials as catalysts in hydrogen production technology from water vapor.

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