938-79-4Relevant academic research and scientific papers
Lumutinines A-D, linearly fused macroline-macroline and macroline-sarpagine bisindoles from Alstonia macrophylla
Lim, Siew-Huah,Tan, Shin-Jowl,Low, Yun-Yee,Kam, Toh-Seok
, p. 2556 - 2562 (2011)
Four new linearly fused bisindole alkaloids, lumutinines A-D (1-4), were isolated from the stem-bark extract of Alstonia macrophylla. Lumutinines A (1) and B (2) represent the first examples of linear, ring A/F-fused macroline-macroline-type bisindoles, w
Lawsozaheer, a new chromone produced by an endophytic fungus Paecilomyces variotii isolated from Lawsonia Alba Lam. inhibits the growth of Staphylococcus aureus
Abbas, Zaheer,Siddiqui, Bina Shaheen,Shahzad, Saleem,Sattar, Samia,Begum, Sabira,Batool, Anum,Choudhary, Mohammad Iqbal
, p. 4448 - 4453 (2021)
One new chromone, lawsozaheer (1), and five known compounds 4-(2-hydroxyethyl) phenol (2), viriditoxin (3), stigmasta-4,6,8(14),22-tetraen-3-one (4), β-sitosterol (5) and stigmasterol (6) were isolated from the fungal broth of Paecilomyces variotii. Their
Macroline, akuammiline, sarpagine, and ajmaline alkaloids from Alstonia macrophylla
Lim, Siew-Huah,Low, Yun-Yee,Sinniah, Saravana Kumar,Yong, Kien-Thai,Sim, Kae-Shin,Kam, Toh-Seok
, p. 204 - 215 (2014)
A total of seventeen alkaloids, comprising six macroline (including alstofolinine A, a macroline indole incorporating a butyrolactone ring-E), two ajmaline, one sarpagine, and eight akuammiline alkaloids, were isolated from the stem-bark and leaf extracts
Novel iridium complex of spirophosphine-carboxylic acid, preparation method and application thereof
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Paragraph 0081-0085, (2017/05/20)
The invention relates to an iridium complex of spirophosphine-carboxylic acid, a preparation method and application thereof. The iridium complex of spirophosphine-carboxylic acid is a compound with a structure shown as formula (I), wherein n=0-3; and the values of R1, R2, R3, R4, R5, R6 and R7 are defined as claim 1. Substituted 7-carboxyl-7'-diarylphosphino-1, 1'-spirobiindane is taken as the ligand to from carboxylic acid anion under the action of alkali, and then complexation with an iridium precursor is carried out to obtain different iridium/spirophosphine-carboxylic acid complexes. The iridium complex of spirophosphine-carboxylic acid provided by the invention can catalyze the asymmetric hydrogenation reaction of a variety of unsaturated carboxylic acids, and show high activity and enantioselectivity, thus having good industrialization prospects. (formula (I)).
Neutral iridium catalysts with chiral phosphine-carboxy ligands for asymmetric hydrogenation of unsaturated carboxylic acids
Yang, Shuang,Che, Wen,Wu, Hui-Ling,Zhu, Shou-Fei,Zhou, Qi-Lin
, p. 1977 - 1980 (2017/03/09)
We developed neutral iridium catalysts with chiral spiro phosphine-carboxy ligands (SpiroCAP) for asymmetric hydrogenation of unsaturated carboxylic acids. Different from the cationic Crabtree-type catalysts, the iridium catalysts with chiral spiro phosphine-carboxy ligands are neutral and do not require the use of a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF?) counterion, which is necessary for stabilizing cationic Crabtree-type catalysts. Another advantage of the neutral iridium catalysts is that they have high stability and have a long lifetime in air. The new iridium catalysts with chiral spiro phosphine-carboxy ligands exhibit unprecedented high enantioselectivity (up to 99.4% ee) in the asymmetric hydrogenations of various unsaturated carboxylic acids, particularly for 3-alkyl-3-methylenepropionic acids, which are challenging substrates for other chiral catalysts.
Entrapment of a chiral cobalt complex within silver: A novel heterogeneous catalyst for asymmetric carboxylation of benzyl bromides with CO2
Yang, Heng-Pan,Yue, Ying-Na,Sun, Qi-Long,Feng, Qiu,Wang, Huan,Lu, Jia-Xing
supporting information, p. 12216 - 12219 (2015/07/27)
A novel way to accommodate heterogeneous catalysis, CO2 fixation and asymmetric synthesis on one catalyst is reported. The [Co]@Ag composite was prepared for the first time and used for asymmetric carboxylation of benzyl bromides with CO2. All the procedures were performed under mild conditions. Moreover, the [Co]@Ag composite has terrific stability and reusability.
Substrate evaluation of rhodococcus erythropolis SET1, a nitrile hydrolysing bacterium, demonstrating dual activity strongly dependent on nitrile sub-structure
Coady, Tracey M.,Coffey, Lee V.,O'Reilly, Catherine,Lennon, Claire M.
supporting information, p. 1108 - 1116 (2015/02/19)
Assessment of Rhodococcus erythropolis SET1, a novel nitrile hydrolysing bacterial isolate, has been undertaken with 34 nitriles, 33 chiral and 1 prochiral. These substrates consist primarily of β-hydroxy nitriles with varying alkyl and aryl groups at the β position and containing in several compounds different substituents α to the nitrile. In the case of β-hydroxy nitriles without substitution at the α position, acids were the major products obtained, along with recovered nitrile after biotransformation, as a result of suspected nitrilase activity of the isolate. Unexpectedly, amides were found to be the major hydrolysis product when the β-hydroxy nitriles possessed a vinyl group at this position. To probe this behaviour further, additional related substrates were evaluated containing electron-withdrawing groups at the α position, and amide was also observed upon biotransformation in the presence of SET1. Therefore this novel isolate has also demonstrated NHase activity with nitriles that appears to be substrate-dependent.
Effect of the concentration of organic modifier in an aqueous-ethanol mobile phase on the chromatographic retention and thermodynamic characteristics of the adsorption of enantiomers of α-phenylcarboxylic acids on silica gel with immobilized eremomycin antibiotic
Blinov,Reshetova
, p. 1778 - 1784 (2014/11/08)
Regularities of the chromatographic retention and thermodynamics of the adsorption of enantiomers of α-phenylcarboxylic acids on a chiral stationary phase with immobilized macrocyclic antibiotic eremomycin under conditions of reversed-phase liquid chromatography with aqueous-ethanol mobile phases are studied. Relationships between the retention characteristics of the acids, the enantioselectivity of their separation, and the concentration of organic modifier in the mobile phase are found. It is shown that the sterical structure of substituents on the chiral atoms of the acids affect the mechanism of retention. The compensation effect in the studied systems is considered.
Laboratory evolution of enantiocomplementary Candida antarctica lipase B mutants with broad substrate scope
Wu, Qi,Soni, Pankaj,Reetz, Manfred T.
supporting information, p. 1872 - 1881 (2013/08/24)
Candida antarctica lipase B (CALB) is a robust and easily expressed enzyme used widely in academic and industrial laboratories with many different kinds of applications. In fine chemicals production, examples include acylating kinetic resolution of racemic secondary alcohols and amines as well as desymmetrization of prochiral diols (or the reverse hydrolytic reactions). However, in the case of hydrolytic kinetic resolution of esters or esterifying kinetic resolution of acids in which chirality resides in the carboxylic acid part of the substrate, rate and stereoselectivity are generally poor. In the present study, directed evolution based on iterative saturation mutagenesis was applied to solve the latter problem. Mutants with highly improved activity and enantioselectivity relative to wild-type CALB were evolved for the hydrolytic kinetic resolution of p-nitrophenyl 2-phenylpropanoate, with the selectivity factor increasing from E = 1.2 (S) to E = 72 (S) or reverting to E = 42 (R) on an optional basis. Surprisingly, point mutations both in the acyl and alcohol pockets of CALB proved to be necessary. Some of the evolved CALB mutants are also efficient biocatalysts in the kinetic resolution of other chiral esters without performing new mutagenesis experiments. Another noteworthy result concerns the finding that enantiocomplementary CALB mutants for α-substituted carboxylic acid esters also show stereocomplementarity in the hydrolytic kinetic resolution of esters derived from chiral secondary alcohols. Insight into the source of stereoselectivity was gained by molecular dynamics simulations and docking experiments.
Enantioselective hydrogenation of α-substituted acrylic acids catalyzed by iridium complexes with chiral spiro aminophosphine ligands
Zhu, Shou-Fei,Yu, Yan-Bo,Li, Shen,Wang, Li-Xin,Zhou, Qi-Lin
supporting information; experimental part, p. 8872 - 8875 (2012/10/08)
Highly active: Iridium complexes with chiral spiro aminophosphine ligands were synthesized and applied as catalysts for the asymmetric hydrogenation of α-substituted acrylic acids (see scheme). The complexes were highly active catalysts, showing turnover frequencies of up to 6000 h-1, and catalyst loadings could be reduced to 0.01 mol %. Copyright
