108211-22-9Relevant academic research and scientific papers
An umpolung approach to the hydroboration of pyridines: A novel and efficient synthesis of: N -H 1,4-dihydropyridines
Yang, Huan,Zhang, Li,Zhou, Fei-Yu,Jiao, Lei
, p. 742 - 747 (2020)
The first inverse hydroboration of pyridine with a diboron(4) compound and a proton source has been realized under simple basic and catalyst-free conditions. This process consists of a formal boryl anion addition to pyridine, which produces an N-boryl pyridyl anion complex, and the subsequent protonation of the anion complex. This process enables a simple and efficient method for the synthesis of multi-substituted N-H 1,4-dihydropyridine (1,4-DHP) derivatives that are difficult to prepare using established methods. Furthermore, this method allows for facile preparation of 4-deuterated 1,4-DHPs from an easily accessible deuterium ion source. This inverse hydroboration reaction represents a new mode for pyridine functionalization.
Highly enantioselective asymmetric isomerization of primary allylic alcohols with an iridium-N,P complex
Li, Jia-Qi,Peters, Byron,Andersson, Pher G.
, p. 11143 - 11145 (2011)
Access to chiral aldehydes: The asymmetric isomerization of primary allylic alcohols was studied with a bicyclic phosphine-oxazoline iridium catalyst. This method displays a broad substrate scope and leads to the desired chiral aldehydes with excellent enantioselectivities (see scheme; R1, R 2=Ar or alkyl). Copyright
EFFECT DE SOLVANT REMARQUABLE DANS L'ADDITION DIASTEREOSELECTIVE D'ORGANOCUPRATES SUR UNE OXAZOLIDINE CHIRALE α,β INSATUREE
Besace, Y.,Berlan, J.,Pourcelot, G.,Huche, M.
, p. C11 - C13 (1983)
In diastereoselective addition of methylcopper and dimethylcuprate to a chiral α-β-ethylenic oxazolidine in Et2O or THF, 3-(S)-phenylbutanal is formed with (ee) in the range of 30 to 50percent.Use of apolar solvents like hexane gives an inversion of configuration and an increase of the enantiomeric excess up to 80percent.
ADDITION DIASTEREOSELECTIVE D'ORGANOCUPRATES A UNE OXAZOLIDINE CHIRALE α,Β INSATUREE: EFFET DE SOLVANT ET APPLICATION DES RESULTATS DE LA RMN 1H A LA DETERMINATION DE LA CONFIGURATION ABSOLUE ET DE LA PURETE OPTIQUE D'ARYL-3-ALKANALS
Berlan, J.,Besace, Y.,Prat, D.,Pourcelot, G.
, p. 399 - 408 (1984)
Addition of lithium dimethylcuprate to the chiral oxazolidine (1) in ether or in hexane leads to 3-phenylbutanals having the S or R configuration, respectively, with high optical yield in the latter case (e.e. = ca. 80percent).The 1H NMR study of the intermediate oxazolidine allows accurate determination of the optical yield and could be applied to the determination of the absolute configuration and optical purity of other 3-arylalkanals.
Optimized iminium-catalysed 1,4-reductions inside the resorcinarene capsule: achieving >90% ee with proline as catalyst
Sokolova, Daria,Tiefenbacher, Konrad
, p. 24607 - 24612 (2021/07/29)
In previous work, we demonstrated that iminium-catalysed 1,4-reductions inside the supramolecular resorcinarene capsule display increased enantioselectivities as compared to their regular solution counterparts. Utilizing proline as the chiral catalyst, enantioselectivities remained below 80% ee. In this study, the reaction conditions were optimized by determining the optimal capsule loading and HCl content. Additionally, it was found that alcohol additives increase the enantioselectivity of the capsule-catalysed reaction. As a result, we report enantioselectivities of up to 92% ee for iminium-catalysed 1,4-reductions relying on proline as the sole chiral source. This is of high interest, as proline is unable to deliver high enantioselectivities for 1,4-reductions in a regular solution setting. Investigations into the role of the alcohol additive revealed a dual role: it not only slowed down the background reaction but also increased the capsule-catalysed reaction rate.
Iridium-Catalyzed Asymmetric Isomerization of Primary Allylic Alcohols Using MaxPHOX Ligands: Experimental and Theoretical Study
Cabré, Albert,Gar?on, Martí,Gallen, Albert,Grisoni, Lorenzo,Grabulosa, Arnald,Verdaguer, Xavier,Riera, Antoni
, p. 4112 - 4120 (2020/07/04)
The asymmetric isomerization of primary allylic alcohols to chiral aldehydes using iridium-catalysts bearing P,N-MaxPHOX ligands has been studied. These catalysts can be fine-tuned as they present three different stereogenic centers to modulate both the reactivity and enantioselectivity of a family of different substrates. The experimental part is supported by a DFT study of the reaction mechanism, which provides new insights into the key steps of this transformation.
1, 4-dihydropyridine bifunctional chiral catalyst and preparation method and application thereof
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Paragraph 0085-0088, (2019/06/30)
The invention belongs to the field of organic catalysis, and discloses a novel 1, 4-dihydropyridine bifunctional chiral catalyst and a preparation method and application thereof. The general chemicalstructure formula of the chiral catalyst is shown in formula (I) as shown in specification. According to the invention, a 1, 4-dihydropyridine derivative and a chiral tetrahydropyrrole derivative areused as raw materials, and finally, the novel 1, 4-dihydropyridine bifunctional chiral catalyst is synthesized. The method has mild synthesis reaction conditions and high yield. The operation steps are simple, safe and reliable; the catalyst is environment-friendly, and can be applied to the fields of asymmetric catalytic transfer hydrogenation, chiral fine chemical synthesis, chiral drug or drugintermediate synthesis, chiral new materials, chiral functional molecule synthesis and the like; and the application prospect is wide.
Design and application of hybrid phosphorus ligands for enantioselective Rh-Catalyzed anti-markovnikov hydroformylation of unfunctionalized 1,1-disubstituted Alkenes
You, Cai,Li, Shuailong,Li, Xiuxiu,Lan, Jialing,Yang, Yuhong,Chung, Lung Wa,Lv, Hui,Zhang, Xumu
supporting information, p. 4977 - 4981 (2018/04/24)
A series of novel hybrid phosphorus ligands were designed and applied to the Rh-catalyzed enantioselective anti-Markovnikov hydroformylation of unfunctionalized 1,1-disubstituted alkenes. By employing the new catalyst, linear aldehydes with β-chirality can be prepared with high yields and enantioselectivities under mild conditions. Furthermore, catalyst loading as low as 0.05 mol % furnished the desired product in good yield and undiminished selectivity, demonstrating the efficiency of this transformation in large-scale synthesis.
CuH-Catalyzed Asymmetric Reduction of α,β-Unsaturated Carboxylic Acids to β-Chiral Aldehydes
Zhou, Yujing,Bandar, Jeffrey S.,Liu, Richard Y.,Buchwald, Stephen L.
supporting information, p. 606 - 609 (2018/01/26)
The copper hydride (CuH)-catalyzed enantioselective reduction of α,β-unsaturated carboxylic acids to saturated aldehydes is reported. This protocol provides a new method to access a variety of β-chiral aldehydes in good yields, with high levels of enantioselectivity and broad functional group tolerance. A reaction pathway involving a ketene intermediate is proposed based on preliminary mechanistic studies and density functional theory calculations.
Iminium Catalysis inside a Self-Assembled Supramolecular Capsule: Scope and Mechanistic Studies
Br?uer, Thomas M.,Zhang, Qi,Tiefenbacher, Konrad
, p. 17500 - 17507 (2017/12/15)
Although iminium catalysis has become an important tool in organic chemistry, its combination with supramolecular host systems has remained largely unexplored. We report the detailed investigations into the first example of iminium catalysis inside a supramolecular host. In the case of 1,4-reductions of α,β-unsaturated aldehydes, catalytic amounts of host are able to increase the enantiomeric excess of the products formed. Several control experiments were performed and provided strong evidence that the modulation of enantiomeric excess of the reaction product indeed stems from a reaction on the inside of the capsule. The origin of the increased enantioselectivity in the capsule was investigated. Furthermore, the substrate and nucleophile scope were studied. Kinetic investigations as well as the kinetic isotope effect measured confirmed that the hydride delivery to the substrate is the rate-determining step inside the capsule. The exploration of benzothiazolidines as alternative hydride sources revealed an unexpected substitution effect of the hydride source itself. The results presented confirm that the noncovalent combination of supramolecular hosts with iminium catalysis is opening up new exciting possibilities to increase enantioselectivity in challenging reactions.
