2743-01-3Relevant articles and documents
Enhancing the efficiency of the ruthenium catalysts in the reductive amination without an external hydrogen source
Afanasyev, Oleg I.,Chusov, Denis,Fatkulin, Artemy R.,Tsygankov, Alexey A.
, p. 404 - 409 (2022/01/13)
Catalytic reductive reactions are essential for laboratory and industrial-scale organic synthesis. However, the nowadays trend is the development of new, progressively more complicated reducing systems, which hinders the application of such highly efficie
Chiral N-heterocyclic carbene-iridium complexes for asymmetric reduction of prochiral ketimines
Kathuria, Lakshay,Samuelson, Ashoka G.
supporting information, (2020/12/28)
Enantioselective reduction of imines to the corresponding chiral secondary amines has been studied using a series of chiral half-sandwich iridium complexes. Chiral N-heterocyclic carbene (NHC) ligands in these complexes were synthesized from readily available, naturally occurring amino acids. Inexpensive phenylsilane was used as a convenient hydrogen donor. Under the optimized conditions, Ir-NHC complexes could reduce ketimines in good yields, albeit with moderate enantiomeric excess (ee). The phenylglycine derived chiral NHC was shown to give the best Ir catalyst and it also gave the maximum ee compared to catalysts prepared from other NHCs in this series. The opposite enantiomer of the reduction product was always obtained while using the Ir complex bearing a valine based NHC. The yields were consistently high with a variety of imine substrates having different steric and electronic demands.
Chan-Lam Amination of Secondary and Tertiary Benzylic Boronic Esters
Dennis, Francesca M.,Grayson, James D.,Partridge, Benjamin M.,Robertson, Craig C.
, p. 9883 - 9897 (2021/07/20)
We report a Chan-Lam coupling reaction of benzylic and allylic boronic esters with primary and secondary anilines to form valuable alkyl amine products. Both secondary and tertiary boronic esters can be used as coupling partners, with mono-alkylation of the aniline occurring selectively. This is a rare example of a transition-metal-mediated transformation of a tertiary alkylboron reagent. Initial investigation into the reaction mechanism suggests that transmetalation from B to Cu occurs through a single-electron, rather than a two-electron process.
Chiral bipyridine-annulated bicyclo[3.3.1]nonane N-oxide organocatalysts for stereoselective allylation and hydrosilylation reactions
?eimyt?, Simona,Ston?ius, Sigitas
supporting information, (2020/12/21)
The synthesis of chiral C2-symmetric bis(bipyridine N,N′-dioxide) and bis(bipyridine N-monooxide) derivatives featuring bipyridine-annulated bicyclo[3.3.1]nonane framework is reported. The new Lewis basic bipyridine N,N′-dioxides exhibited good
Implication of a Silyl Cobalt Dihydride Complex as a Useful Catalyst for the Hydrosilylation of Imines
Barbazanges, Marion,Bories, Cassandre C.,Derat, Etienne,Petit, Marc
, p. 14262 - 14273 (2021/11/27)
Here, we describe the formation and use of silyl cobalt (III) dihydride complexes as powerful catalysts for the hydrosilylation of a variety of imines starting from a low-valent well-defined cobalt (I) complex. The reaction is efficient at low catalyst loadings with a diverse range of imines bearing various protecting groups, as well as aliphatic ketimines and quinoline. Kinetics, DFT calculations, NMR spectroscopic studies, deuteration experiments, and X-ray diffraction analyses allowed us to propose a catalytic cycle based on silyl dihydrocobalt (III) complexes performing a hydrocobaltation.
Rhodium catalysts with cofactor mimics for the biomimetic reduction of CN bonds
Chen, Fushan,Deng, Li,Dong, Wenjin,Tang, Jie,Xian, Mo
, p. 5564 - 5569 (2021/08/25)
A strategy based on the cooperation between metal and bonded cofactor mimics was applied to the transfer hydrogenation of CN bonds. We designed and synthesized a rhodium complex containing a 1,3-dimethylbenzoimidazole moiety, which could transfer hydride from a rhodium center to imine substrates in a biomimetic way. Under both transfer hydrogenation and reductive amination reaction conditions, the catalyst exhibited good selectivity towards CN bonds. With the catalyst, 34 imines were transfer hydrogenated to corresponding amines and a key intermediate of retigabine was prepared via reductive amination in a greener way. According to the NMR observations and isotope experiments, a plausible mechanism for this biomimetic reduction of CN bonds were proposed.
Phosphine ligands in the ruthenium-catalyzed reductive amination without an external hydrogen source
Makarova, Maria,Afanasyev, Oleg I.,Kliuev, Fedor,Nelyubina, Yulia V.,Godovikova, Maria,Chusov, Denis
, (2021/04/15)
A systematic study of the phosphine additives influence on the activity of a ruthenium catalyst in reductive amination without an external hydrogen source was carried out. [CymeneRuCl2]2 was used as a reference catalyst, and a broad set of phosphines including Alk3P, Alk2ArP, Ar3P and X3P was screened. Three complexes of general formula (Cymene)RuCl2PR3 were isolated in a pure form, and their catalytic activity was compared with the in situ generated complexes. Nonhindered triarylphosphines with electron acceptor groups were found to be the most perspective activating agents, increasing the activity of the catalyst approx. six times, Alk2ArP ligands have less noticeable influence, while trialkylphosphines strongly deactivate the ruthenium catalyst.
Carbon monoxide-driven osmium catalyzed reductive amination harvesting WGSR power
Afanasyev, Oleg I.,Biriukov, Klim O.,Chusov, Denis,Godovikova, Maria,Loginov, Dmitry A.,Nelyubina, Yulia V.,Tsygankov, Alexey A.,Vasilyev, Dmitry V.,Vinogradov, Mikhail M.
, p. 4922 - 4930 (2021/07/26)
Herein, we present the first example of Os-catalyzed efficient reductive amination under water-gas shift reaction conditions. The developed catalytic systems are formedin situin aqueous solutions, employ as small as 0.0625 mol% osmium and are capable of delivering reductive amination products for a broad range of aliphatic and aromatic carbonyl compounds and amines. The scope of the reaction, active catalytic systems, possible limitations of the method and DFT-supported mechanistic considerations are discussed in detail in the manuscript.
Chiral Arylated Amines via C?N Coupling of Chiral Amines with Aryl Bromides Promoted by Light
Cao, Rui,Li, Jing-Sheng,Song, Geyang,Tang, Wei-Jun,Wang, Chao,Xiao, Jianliang,Xue, Dong,Yang, Liu,Zhang, Wei
supporting information, p. 21536 - 21542 (2021/08/23)
The Buchwald-Hartwig C-N coupling reaction has found widespread applications in organic synthesis. Over the past two decades or so, many improved catalysts have been introduced, allowing various amines and aryl electrophiles to be readily used nowadays. However, there lacks a protocol that could be used to couple a wide range of chiral amines and aryl halides, without erosion of the enantiomeric excess (ee). Reported in this article is a method based on molecular Ni catalysis driven by light, which enables stereoretentive C-N coupling of optically active amines, amino alcohols, and amino acid esters with aryl bromides, with no need for any external photosensitizer. The method is effective for a wide variety of coupling partners, including those bearing functional groups sensitive to bases and nucleophiles, thus providing a viable alternative to accessing synthetically important chiral N-aryl amines, amino alcohols, and amino acids esters. Its viability is demonstrated by 92 examples with up to 99 % ee.
Chiral cyclometalated iridium complexes for asymmetric reduction reactions
Smith, Jennifer,Kacmaz, Aysecik,Wang, Chao,Villa-Marcos, Barbara,Xiao, Jianliang
supporting information, p. 279 - 284 (2021/01/18)
A series of chiral cyclometalated iridium complexes have been synthesised by cyclometalating chiral 2-aryl-oxazoline and imidazoline ligands with [Cp?IrCl2]2. These iridacycles were studied for asymmetric transfer hydrogenation reactions with formic acid as the hydrogen source and were found to display various activities and enantioselectivities, with the most effective ones affording up to 63% ee in the asymmetric reductive amination of ketones and 77% ee in the reduction of pyridinium ions. This journal is
