19926-90-0Relevant academic research and scientific papers
Triruthenium carbonyl clusters derived from chiral aminooxazolines: Synthesis and catalytic activity
Cabeza, Javier A.,Da Silva, Ivan,Del Rio, Ignacio,Gossage, Robert A.,Miguel, Daniel,Suarez, Marta
, p. 2450 - 2455 (2006)
Treatment of [Ru3(CO)12] with the chiral aminooxazolines (+)-2-amino-(4R)-phenyl-2-oxazoline (H2amphox), (+)-2-amino-(4R,5S)-indanyl-2-oxazoline (H2aminox) and (+)-2-(2′-anilinyl)-(4R,5S)-indanyl-2-oxazoline (H2aninox) in THF at reflux temperature, affords the complexes [Ru3(-H)( 3-κ2-Hox-N,N)(CO)9] (H2ox = H2amphox, 1; H2aminox, 2) and [Ru3(-H)(- κ2-Haninox-N,N)(CO)9] (3). In all cases, the activation of an N-H bond has occurred and the resulting amido fragment spans an edge of the metal triangle, while the N atom of the oxazoline ring is attached to the remaining metal atom (as in 1 and 2), or to one of the metal atoms of the bridged edge (as in 3). The use of 1-3 as catalyst precursors in the asymmetric hydrogen-transfer reduction of acetophenone and in the asymmetric cycloaddition of cyclopentadiene and acroleine is reported. The Royal Society of Chemistry 2006.
Method for preparing single-configuration C-2-position-monosubstituted norbornene derivative
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, (2021/07/01)
The invention discloses a method for preparing a single-configuration C-2-position-monosubstituted norbornene derivative. The method comprises the following steps of: firstly, preparing exo-isomer enriched exo-isomer mixed 5-norbornene-2-carboxylic ester by taking commercial exo-isomer/endoisomer mixed 5-norbornene-2-carboxylic acid and large-steric-hindrance monohydric alcohol as raw materials; separating 5-norbornene-2-carboxylate with a single configuration through common column chromatography separation or fractionation; and finally, preparing the C-2-position-monosubstituted norbornene derivative with the single configuration from the separated 5-norbornene-2-carboxylate with the single configuration. The raw materials used in the invention are easy to obtain, the preparation process is simple, and the C-2-position-monosubstituted norbornene derivative with high purity (greater than 98%) and single configuration can be obtained.
Bis-selenonium Cations as Bidentate Chalcogen Bond Donors in Catalysis
He, Xinxin,Wang, Xinyan,Tse, Ying-Lung Steve,Ke, Zhihai,Yeung, Ying-Yeung
, p. 12632 - 12642 (2021/10/21)
Lewis acids are frequently employed in catalysis but they often suffer from high moisture sensitivity. In many reactions, catalysts are deactivated because of the problem that strong Lewis acids also bond to the products. In this research, hydrolytically stable bidentate Lewis acid catalysts derived from selenonium dicationic centers have been developed. The bis-selenonium catalysts are employed in the activation of imine and carbonyl groups in various transformations with good yields and selectivity. Lewis acidity of the bis-selenonium salts was found to be stronger than that of the monoselenonium systems, attributed to the synergistic effect of the two cationic selenonium centers. In addition, the bis-selenonium catalysts are not inhibited by strong bases or moisture.
NOVEL BENZOIMIDAZOLES AS SELECTIVE INHIBITORS OF INDOLEAMINE 2, 3-DIOXYGENASES
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Paragraph 0556; 0557, (2019/06/11)
Disclosed herein are novel benzoimidazoles and pharmaceutical compositions comprising at least one such novel benzoimidazoles, processes for the preparation thereof, and the method for using the same in therapy. In particular, disclosed herein are certain novel benzoimidazoles that are useful for inhibiting indoleamine 2, 3-dioxygenase and for treating diseases or disorders mediated thereby.
Oxidative Dehomologation of Aldehydes with Oxygen as a Terminal Oxidant
Shipilovskikh, Sergei A.,Rubtsov, Aleksandr E.,Malkov, Andrei V.
, p. 6760 - 6762 (2017/12/26)
A mild, efficient protocol for oxidative cleavage of C-C bonds in aldehydes has been developed that employs alkali metal hydrides as reagents and oxygen from air as a terminal oxidant. The method is applicable to a broad substrate range.
Improving the efficiency of the Diels-Alder process by using flow chemistry and zeolite catalysis
Seghers,Protasova,Mullens,Thybaut,Stevens
supporting information, p. 237 - 248 (2017/08/14)
The industrial application of the Diels-Alder reaction for the atom-efficient synthesis of (hetero)cyclic compounds constitutes an important challenge. Safety and purity concerns, related to the instability of the polymerization prone diene and/or dienophile, limit the scalability of the production capacity of Diels-Alder products in a batch mode. To tackle these problems, the use of a high-pressure continuous microreactor process was considered. In order to increase the yields and the selectivity towards the endo-isomer, commercially available zeolites were used as a heterogeneous catalyst in a microscale packed bed reactor. As a result, a high conversion (≥95%) and endo-selectivity (89:11) were reached for the reaction of cyclopentadiene and methyl acrylate, using a 1:1 stoichiometry. A throughput of 0.87 g h-1 during at least 7 h was reached, corresponding to a 3.5 times higher catalytic productivity and a 14 times higher production of Diels-Alder adducts in comparison to the heterogeneous lab-scale batch process. Catalyst deactivation was hardly observed within this time frame. Moreover, complete regeneration of the zeolite was demonstrated using a straightforward calcination procedure.
NOVEL 5 OR 8-SUBSTITUTED IMIDAZO [1, 5-a] PYRIDINES AS INDOLEAMINE AND/OR TRYPTOPHANE 2, 3-DIOXYGENASES
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Paragraph 0491, (2016/10/31)
Disclosed herein are 5 or 8-substituted imidazo[l,5-a]pyridines and pharmaceutical compositions comprising at least one such 5 or 8-substituted imidazo[l,5-a]pyridines, processes for the preparation thereof, and the use thereof in therapy. Disclosed herein are certain 5 or 8- substituted imidazo[l,5-a]pyridines that can be useful for inhibiting indoleamine 2,3- dioxygenase and/or tryptophane 2,3-dioxygenase and for treating diseases or disorders mediated thereby.
Method for preparing 5-norbornene-2-formaldehyde in microstructure reactor
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Paragraph 0029; 0030, (2017/04/03)
The invention relates to a method for preparing 5-norbornene-2-formaldehyde in a microstructure reactor. 5-Norbornene-2-formaldehyde is generated through a Diels-Alder reaction of acrolein and cyclopentadiene in the microstructure reactor. Present industrial production technologies have the disadvantages of long reaction time and difficult removal of generated polymers adhered to a reaction device. The method for preparing 5-norbornene-2-formaldehyde in the microstructure reactor at a high temperature under a high pressure has the advantages of short reaction time and no generation of solids.
Remote Tris(pentafluorophenyl)borane-Assisted Chiral Phosphoric Acid Catalysts for the Enantioselective Diels-Alder Reaction
Hatano, Manabu,Ishihara, Hideyuki,Goto, Yuta,Ishihara, Kazuaki
, p. 564 - 570 (2016/03/12)
Tris(pentafluorophenyl)borane-assisted chiral supramolecular phosphoric acid catalysts were developed for the model Diels-Alder reaction of α-substituted acroleins with cyclopentadiene. Two remotely coordinated tris(pentafluorophenyl)boranes should help to increase the Bronsted acidity of the active center in the supramolecular catalyst and create effective bulkiness for the chiral cavity. The prepared supramolecular catalysts acted as not only conjugated Bronsted acid-Bronsted base catalysts but also bifunctional Lewis acid-Bronsted base catalysts with the addition of a central achiral Lewis acid source such as catecholborane.
Ruthenium Lewis Acid-Catalyzed Asymmetric Diels–Alder Reactions: Reverse-Face Selectivity for α,β-Unsaturated Aldehydes and Ketones
Thamapipol, Sirinporn,Ludwig, Bettina,Besnard, Céline,Saudan, Christophe,Kündig, E. Peter
, p. 774 - 789 (2016/10/17)
Acrolein, methacrolein, methyl vinyl ketone, ethyl vinyl ketone, 3-methyl-3-en-2-one, and divinyl ketone were coordinated to a cationic cyclopentadienyl ruthenium(II) Lewis acid incorporating the electron-poor bidentate BIPHOP–F ligand. Analysis by NOESY and ROESY NMR techniques allowed the determination of conformations of enals and enones present in solution in CD2Cl2. The results were compared to solid-state structures and to the facial selectivities of catalytic asymmetric Diels–Alder reactions with cyclopentadiene. X-Ray structures of four Ru-enal and Ru-enone complexes show the α,β-unsaturated C=O compounds to adopt an anti-s-trans conformation. In solution, enals assume both anti-s-trans and anti-s-cis conformations. An additional conformation, syn-s-trans, is present in enone complexes. Enantioface selectivity in the cycloaddition reactions differs for enals and enones. Reaction products indicate enals to react exclusively in the anti-s-trans conformation, whereas with enones, the major product results from the syn-s-trans conformation. The alkene in s-cis conformations, while present in solution, is shielded and cannot undergo cycloaddition. A syn-s-trans conformation is found in the solid state of the bulky 6,6-dimethyl cyclohexanone-Ru(II) complex. The X-ray structure of divinyl ketone is unique in that the Ru(II) center binds the enone via a η2bond to one of the alkene moieties. In solution, coordination to Ru–C=O oxygen is adopted. A comparison of facial preference is also made to the corresponding indenyl Lewis acids.
