61403-68-7Relevant academic research and scientific papers
OXA-SPIRODIPHOSPHINE LIGAND AND METHOD FOR ASYMMETRIC HYDROGENATION OF alpha, beta-UNSATURATED CARBOXYLIC ACIDS
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Paragraph 0028; 0033, (2021/11/05)
The present invention provides an oxa-spirodiphosphine ligand having a structure of general Formula (I) below: wherein in general Formula (I), R1, R2, R3 and R4 are the same, and are alkyl, alkoxy, aryl, aryloxy
Cobalt-Catalyzed Asymmetric Hydrogenation of α,β-Unsaturated Carboxylic Acids by Homolytic H2 Cleavage
Chirik, Paul J.,Shevlin, Michael,Zhong, Hongyu
supporting information, (2020/03/13)
The asymmetric hydrogenation of α,β-unsaturated carboxylic acids using readily prepared bis(phosphine) cobalt(0) 1,5-cyclooctadiene precatalysts is described. Di-, tri-, and tetra-substituted acrylic acid derivatives with various substitution patterns as well as dehydro-α-amino acid derivatives were hydrogenated with high yields and enantioselectivities, affording chiral carboxylic acids including Naproxen, (S)-Flurbiprofen, and a d-DOPA precursor. Turnover numbers of up to 200 were routinely obtained. Compatibility with common organic functional groups was observed with the reduced cobalt(0) precatalysts, and protic solvents such as methanol and isopropanol were identified as optimal. A series of bis(phosphine) cobalt(II) bis(pivalate) complexes, which bear structural similarity to state-of-the-art ruthenium(II) catalysts, were synthesized, characterized, and proved catalytically competent. X-band EPR experiments revealed bis(phosphine)cobalt(II) bis(carboxylate)s were generated in catalytic reactions and were identified as catalyst resting states. Isolation and characterization of a cobalt(II)-substrate complex from a stoichiometric reaction suggests that alkene insertion into the cobalt hydride occurred in the presence of free carboxylic acid, producing the same alkane enantiomer as that from the catalytic reaction. Deuterium labeling studies established homolytic H2 (or D2) activation by Co(0) and cis addition of H2 (or D2) across alkene double bonds, reminiscent of rhodium(I) catalysts but distinct from ruthenium(II) and nickel(II) carboxylates that operate by heterolytic H2 cleavage pathways.
Oxa-spiral diphosphine ligand and application thereof in alpha, beta-unsaturated carboxylic acid asymmetric hydrogenation
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Paragraph 0039; 0047, (2019/04/04)
The invention provides an oxa-spiral diphosphine ligand. The oxa-spiral diphosphine ligand has a structure shown by a general formula (I) as shown in description, wherein R1, R2, R3 and R4 in the general formula (I) are same and are alkyl, alkoxy, aryl, aroxyl, or hydrogen atoms; R1, R2, R3 and R4 comprise forms of ring formation, non-ring formation, any two ring formation or multiple-ring formation between pairs; R5 and R6 are alkyl, aryl or hydrogen atoms; and R7 and R8 are alkyl or benzyl or aryl. The invention further provides application of the oxa-spiral diphosphine ligand O-SDP in the alpha, beta-unsaturated carboxylic acid asymmetric hydrogenation. A complex of the oxa-spiral diphosphine ligand O-SDP and ruthenium has excellent activity and enantioselectivity in the asymmetric hydrogenation of the alpha, beta-unsaturated carboxylic acid in multiple types, and a chiral carboxylic acid product is obtained with the enantioselectivity being up to 99%. The synthesis method can be applied to the construction of a core skeleton of chemical molecules with important activity, wherein the chemical molecules comprise Paroxetine, Femoxetine, nipecotic acid and Sacubitril.
Stereodivergence in the Ireland-Claisen Rearrangement of α-Alkoxy Esters
Podunavac, Ma?a,Lacharity, Jacob J.,Jones, Kerry E.,Zakarian, Armen
, p. 4867 - 4870 (2018/08/24)
A systematic investigation into the Ireland-Claisen rearrangement of α-alkoxy esters is reported. In all cases, the use of KN(SiMe3)2 in toluene gave rearrangement products corresponding to a Z-enolate intermediate with excellent diastereoselectivity, presumably because of chelation control. On the other hand, chelation-controlled enolate formation could be overcome for most substrates through the use of lithium diisopropylamide (LDA) in tetrahydrofuran (THF).
Highly enantioselective hydrogenation of α-oxy functionalized α,β-unsaturated acids catalyzed by a ChenPhos-Rh complex in CF3CH2OH
Yao, Lin,Wen, Jialin,Liu, Shaodong,Tan, Renchang,Wood, Noel Marie,Chen, Weiping,Zhang, Shengyong,Zhang, Xumu
supporting information, p. 2273 - 2276 (2016/02/18)
Rhodium complexes coordinated by Chenphos are very effective catalysts for the enantioselective hydrogenation of α-aryloxy- and α-alkoxy-substituted α,β-unsaturated carboxylic acids under mild conditions in CF3CH2OH. The catalytic system could be successfully employed in building the core structure of a new FDA approved drug LCZ 696.
Asymmetric hydrogenation method of alpha-oxo-alpha, beta-unsaturated carboxylic acid
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Paragraph 0023; 0024; 0025; 0026, (2016/10/09)
The invention relates to an asymmetric hydrogenation method of alpha-oxo-alpha, beta-unsaturated carboxylic acid. A metal complex containing ChenPhos chiral ligand is a catalyst high in conversion efficiency, and particularly, the catalyst can be used for
Enantioselective hydrogenation of α-aryloxy and α-alkoxy α,β-unsaturated carboxylic acids catalyzed by chiral spiro iridium/phosphino-oxazoline complexes
Li, Shen,Zhu, Shou-Fei,Xie, Jian-Hua,Song, Song,Zhang, Can-Ming,Zhou, Qi-Lin
supporting information; experimental part, p. 1172 - 1179 (2010/04/01)
The iridium-catalyzed highly enantioselective hydrogenation of α-aryloxy and α-alkoxy-substituted α,β-unsaturated carboxylic acids was developed. By using chiral spiro phosphino-oxazoline ligands, the hydrogenation proceeded smoothly to produce various α-aryloxy- and α-alkoxy-substituted carboxylic acids with extremely high enantioselectivities (ee up to 99.8%) and reactivities (TON up to 10 000) under mild conditions. The hydrogenation of R-benzyloxy-substituted α,β-unsaturated acids provided an efficient alternative for the synthesis of chiral R-hydroxy acids after an easy deprotection. A mechanism involving a catalytic cycle between IrI and IrIII was proposed on the basis of the coordination model of the unsaturated acids with the iridium metal center. The rationality of the catalytic cycle, with an olefin dihydride complex as the key intermediate, was supported by the deuterium-labeling studies. The X-ray diffraction analysis of the single crystal of catalyst revealed that the rigid and sterically hindered chiral environment created by the spiro phosphino-oxazoline ligands is the essential factor that permits the catalyst to obtain excellent chiral discrimination. A chiral induction model was suggested on the basis of the catalyst structure and the product configuration.
Design and synthesis of 2- and 3-substituted-3-phenylpropyl analogs of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine and 1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine: Role of amino, fluoro, hydroxyl, methoxyl, methyl, methylene, and oxo substituents on affinity for the dopamine and serotonin transporters
Hsin, Ling-Wei,Chang, Li-Te,Rothman, Richard B.,Dersch, Christina M.,Jacobson, Arthur E.,Rice, Kenner C.
, p. 2795 - 2806 (2008/12/22)
Novel derivatives of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3- phenylpropyl)piperazine (GBR 12909, 1) and 1-[2-(diphenylmethoxy)ethyl]-4-(3- phenylpropyl)piperazine (GBR 12935, 2) with various substituents in positions C2 and C3 of the phenylpropyl side chain were synthesized and evaluated for their ability to bind to the dopamine transporter (DAT) and the serotonin transporter (SERT). In the C2 series, the substituent in the S-configuration, with a lone-pair of electrons, significantly enhanced the affinity for DAT, whereas the steric effect of the substituent was detrimental to DAT binding affinity. In the C3 series, neither the lone electron pair nor the steric effect of the substituent seemed to affect DAT binding affinity, while sp2 hybridized substituents had a detrimental effect on affinity for DAT. In the series, the 2-fluoro-substituted (S)-10 had the highest DAT binding affinity and good DAT selectivity, while the 2-amino-substituted (R)-8 showed essentially the same affinity for DAT and SERT. The oxygenated 16 and 18 possessed the best selectivity for DAT.
Asymmetric hydrogenation of α,β-unsaturated carboxylic acids catalyzed by ruthenium(II) complexes of spirobifluorene diphosphine (SFDP) ligands
Cheng, Xu,Xie, Jian-Hua,Li, Sheng,Zhou, Qi-Lin
, p. 1271 - 1276 (2007/10/03)
The ruthenium diacetate complexes ligated by chiral spirobifluorene diphosphines (SFDP) were very effective catalysts for the asymmetric hydrogenation of tiglic acid derivatives and α-methylcinnamic acid derivatives with high activities and excellent enantioselectivities (up to 98% ee). The α-aryloxybutenoic acids can also be hydrogenated by these catalysts to provide the corresponding saturated α-aryloxybutanoic acids in high yields (89-93%) and enantioselectivities (up to 95% ee). In this reaction, the SFDP ligand with para-methyl groups on the P-phenyl rings gave the best results.
