- Enantioselective Aminohydroxylation of Styrenyl Olefins Catalyzed by an Engineered Hemoprotein
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Chiral 1,2-amino alcohols are widely represented in biologically active compounds from neurotransmitters to antivirals. While many synthetic methods have been developed for accessing amino alcohols, the direct aminohydroxylation of alkenes to unprotected, enantioenriched amino alcohols remains a challenge. Using directed evolution, we have engineered a hemoprotein biocatalyst based on a thermostable cytochrome c that directly transforms alkenes to amino alcohols with high enantioselectivity (up to 2500 TTN and 90 % ee) under anaerobic conditions with O-pivaloylhydroxylamine as an aminating reagent. The reaction is proposed to proceed via a reactive iron-nitrogen species generated in the enzyme active site, enabling tuning of the catalyst's activity and selectivity by protein engineering.
- Cho, Inha,Prier, Christopher K.,Jia, Zhi-Jun,Zhang, Ruijie K.,G?rbe, Tamás,Arnold, Frances H.
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supporting information
p. 3138 - 3142
(2019/02/01)
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- Norepinephrine alkaloids as antiplasmodial agents: Synthesis of syncarpamide and insight into the structure-activity relationships of its analogues as antiplasmodial agents
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Syncarpamide 1, a norepinephrine alkaloid isolated from the leaves of Zanthoxylum syncarpum (Rutaceae) exhibited promising antiplasmodial activities against Plasmodium falciparum with reported IC50 values of 2.04 μM (D6 clone), 3.06 μM (W2 clone) and observed by us 3.90 μM (3D7 clone) and 2.56 μM (K1 clone). In continuation of our work on naturally occurring antimalarial compounds, synthesis of syncarpamide 1 and its enantiomer, (R)-2 using Sharpless asymmetric dihydroxylation as a key step has been accomplished. In order to study structure-activity-relationship (SAR) in detail, a library of 55 compounds (3–57), which are analogues/homologues of syncarpamide 1 were synthesized by varying the substituents on the aromatic ring, by changing the stereocentre at the C-7 and/or by varying the acid groups in the ester and/or amide side chain based on the natural product lead molecule and further assayed in vitro against 3D7 and K1 strains of P. falciparum to evaluate their antiplasmodial activities. In order to study the effect of position of functional groups on antiplasmodial activity profile, a regioisomer (S)-58 of syncarpamide 1 was synthesized however, it turned out to be inactive against both the strains. Two compounds, (S)-41 and its enantiomer, (R)-42 having 3,4,5-trimethoxy cinnamoyl groups as side chains showed better antiplasmodial activity with IC50 values of 3.16, 2.28 μM (3D7) and 1.78, 2.07 μM (K1), respectively than the natural product, syncarpamide 1. Three compounds (S)-13, (S)-17, (S)-21 exhibited antiplasmodial activities with IC50 values of 6.39, 6.82, 6.41 μM against 3D7 strain, 4.27, 7.26, 2.71 μM against K1 strain and with CC50 values of 147.72, 153.0, >200 μM respectively. The in vitro antiplasmodial activity data of synthesized library suggests that the electron density and possibility of resonance in both the ester and amide side chains increases the antiplasmodial activity as compared to the parent natural product 1. The natural product syncarpamide 1 and four analogues/homologues out of the synthesized library of 55, (S)-41, (R)-42, (S)-55 and (S)-57 were assayed in vivo assay against chloroquine-resistant P. yoelii (N-67) strain of Plasmodium. However, none of the five molecules, 1, (S)-41, (R)-42, (S)-55 and (S)-57 exhibited any promising in vivo antimalarial activity against P. yoelii (N-67) strain. Compounds 4, 6, 7 and 11 showed high cytotoxicities with CC50 values of 5.87, 5.08, 6.44 and 14.04 μM, respectively. Compound 6 was found to be the most cytotoxic as compared to the standard drug, podophyllotoxin whereas compounds 4 and 7 showed comparable cytotoxicities to podophyllotoxin.
- Aratikatla, Eswar K.,Valkute, Tushar R.,Puri, Sunil K.,Srivastava, Kumkum,Bhattacharya, Asish K.
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p. 1089 - 1105
(2017/08/03)
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- One-pot combination of enzyme and Pd nanoparticle catalysis for the synthesis of enantiomerically pure 1,2-amino alcohols
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One-pot combinations of sequential catalytic reactions can offer practical and ecological advantages over classical multi-step synthesis schemes. In this context, the integration of enzymatic and chemo-catalytic transformations holds particular potential for efficient and selective reaction sequences that would not be possible using either method alone. Here, we report the one-pot combination of alcohol dehydrogenase-catalysed asymmetric reduction of 2-azido ketones and Pd nanoparticle-catalysed hydrogenation of the resulting azido alcohols, which gives access to both enantiomers of aromatic 1,2-amino alcohols in high yields and excellent optical purity (ee >99%). Furthermore, we demonstrate the incorporation of an upstream azidolysis and a downstream acylation step into the one-pot system, thus establishing a highly integrated synthesis of the antiviral natural product (S)-tembamide in 73% yield (ee >99%) over 4 steps. Avoiding the purification and isolation of intermediates in this synthetic sequence leads to an unprecedentedly low ecological footprint, as quantified by the E-factor and solvent demand.
- Schrittwieser, Joerg H.,Coccia, Francesca,Kara, Selin,Grischek, Barbara,Kroutil, Wolfgang,D'Alessandro, Nicola,Hollmann, Frank
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p. 3318 - 3331
(2013/12/04)
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- Asymmetric reduction of α-keto aldoxime o -ethers
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The catalytic asymmetric reduction of -keto aldoxime O-methyl, O-benzyl, and O-trityl ethers, derived from substituted acetophenones, with borane/oxazaborolidines, by transfer hydrogenation, and with yeast, was studied. The reduction with borane/oxazaborolidines produced the corresponding -hydroxy oxime ethers, -hydroxy hydroxylamine ethers, and -amino alcohols in 39-78% yields and up to 77% ee. The carbonyl group was selectively reduced by transfer hydrogenation with formic acid-triethylamine catalyzed by RhCl[(R,R)-TsDPEN](Ce, and also with yeast, producing -hydroxy oxime ethers, up to 75% ee and 93% ee, respectively. Georg Thieme Verlag Stuttgart New York.
- Bosiak, Mariusz J.,Pakulski, Marcin M.
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p. 316 - 324
(2011/03/18)
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- Asymmetric hydrogenation of α-primary and secondary amino ketones: Efficient asymmetric syntheses of (-)-arbutamine and (-)-denopamine
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Two ss-receptor agonists (-)-denopamine and (-)-arbutamine were prepared in good yields and enantioselectivities by asymmetric hydrogenation of unprotected amino ketones for the first time by using Rh catalysts bearing electron-donating phosphine ligands. A series of α-primary and secondary amino ketones were synthesized and hydrogenated to produce various 1,2-amino alcohols in good yields and with good enantioselectivies. This Rh electron-donating phosphine-catalyzed asymmetric hyderogenation repI resents one of the most promising and convenient approaches towards the asymmetric synthesis of chiral amino alcohols.
- Shang, Gao,Liu, Duan,Allen, Scott E.,Yang, Qin,Zhang, Xumu
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p. 7780 - 7784
(2008/04/03)
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- COMPOUNDS AND METHODS FOR TREATMENT OF CANCER AND MODULATION OF PROGRAMMED CELL DEATH FOR MELANOMA AND OTHER CANCER CELLS
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Compounds and related methods for synthesis, and the use of compounds and combination therapies for the treatment of cancer and modulation of apoptosis in cells are disclosed. The generation of synthetic combinatorial libraries and the evaluation of library member compounds regarding induction of apoptosis selectively in cancer cells are disclosed. Compounds, methods of making the compounds, and therapeutic methods with application against breast cancer cells, melanoma cancer cells, colon cancer cells, and other cancer cells are described.
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Page/Page column 39
(2008/06/13)
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- Chemoenzymatic synthesis of (R)- and (S)-tembamide, aegeline and denopamine by a one-pot lipase resolution protocol
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An efficient synthesis of optically active β-azido alcohols from their ketoazides by a one-pot reduction and an in situ lipase resolution protocol is described. The synthetic utility of this procedure has been illustrated by its application in the practic
- Kamal, Ahmed,Shaik, Ahmad Ali,Sandbhor, Mahendra,Malik, M. Shaheer
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p. 3939 - 3944
(2007/10/03)
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- Identification from a Combinatorial Library of a Small Molecule that Selectively Induces Apoptosis in Cancer Cells
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The selective induction of death in cancer cells is a major challenge in modern medicine. In this communication we describe the synthesis of an 88-membered combinatorial library, and the subsequent evaluation of these compounds for their ability to selectively induce apoptosis in cancerous cells. A compound was identified from the library that induces apoptosis in U-937 and HL-60 cell lines. This compound is a remarkably selective pro-apoptotic agent for these cancer cell lines, as it does not induce significant death in noncancerous white blood cells, even at concentrations as high as 1000 μM. Copyright
- Nesterenko, Vitaliy,Putt, Karson S.,Hergenrother, Paul J.
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p. 14672 - 14673
(2007/10/03)
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- Baker's Yeast Reduction of α-(Acylamino)acetophenones and Lipase Catalyzed Resolution of 2-Acylamino-1-arylethanols
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Enzymatic reduction of α-acylaminoacetophenones with fermenting baker's yeast afforded optically active (R)-2-acylamino-1-arylethanols.Furthermore, lipase-catalyzed resolution of the 2-acylamino-1-arylethanols using vinyl acetate as an acyl donor resulted in the formation of (S)-1-acetoxy-2-acylamino-1-arylethanols and (R)-2-acylamino-1-arylethanols.
- Izumi, Taeko,Fukaya, Katsumi
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p. 1216 - 1221
(2007/10/02)
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