- Amino Group Functionalized Hf-Based Metal-Organic Framework for Knoevenagel-Doebner Condensation
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A Hf(IV) metal-organic framework (MOF) with di-amino functionalized linker was obtained as a crystalline solid with UiO-67 topology under solvothermal reaction conditions. The guest free form of Hf(IV) MOF (1′) was efficiently employed as a heterogeneous catalyst to synthesize cinnamic acid derivatives via Knoevenagel-Doebner reaction for the first time. The catalyst (1′) was efficiently active to directly achieve cinnamic acid from benzaldehyde and malonic acid. The solid retained its activity up to 6th cycle with no decay in its activity. The noticeable advantages of the catalyst are its milder reaction conditions, high yield, high stability, recyclable nature towards catalysis and wide substrate scope as well as shape-selective behaviour. The possible mechanism of the reaction was also studied thoroughly with suitable control experiments.
- Das, Aniruddha,Anbu, Nagaraj,Gogoi, Chiranjib,Dhakshinamoorthy, Amarajothi,Biswas, Shyam
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p. 3396 - 3403
(2021/08/20)
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- Knoevenagel-Doebner condensation promoted by chitosan as a reusable solid base catalyst
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The development of green and sustainable processes using naturally occurring biopolymers is becoming one of the suitable remedies to replace the conventional catalytic systems that generate large amount of byproducts with high risk factors. In this context, although Knoevenagel-Doebner condensation reaction has been reported with many organocatalysts including proline, no attempts were made to develop heterogeneous catalysts with environmental concerns. Considering these factors in mind, the title reaction is studied with chitosan as a heterogeneous solid base catalyst for the synthesis of α,β-unsaturated carboxylic acids through the condensation followed by decarboxylation reactions. Chitosan offers many advantages including high stability as evidenced by leaching, reusability tests, wide substrate scope and providing higher yields of the desired products with high purity. Powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscope (SEM) and elemental analysis revealed that there are no major changes in the structural integrity and morphology of chitosan before and after catalysis under the optimized reaction conditions.
- Anbu, Nagaraj,Hariharan, Surendran,Dhakshinamoorthy, Amarajothi
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- Coenzyme A-Conjugated Cinnamic Acids – Enzymatic Synthesis of a CoA-Ester Library and Application in Biocatalytic Cascades to Vanillin Derivatives
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We present a bioorthogonal method for the ligation of coenzyme A (CoA) with cinnamic acids. The reaction, which is the initial step in the biosynthesis of a multitude of bioactive secondary metabolites, is catalyzed by a promiscuous plant ligase and yields CoA conjugates with different functionalization in high purity and without formation of by-products. Its applicability in biosynthetic cascades is shown for the direct transformation of cinnamic acids into natural benzaldehydes (like vanillin) or artificial derivatives (e. g. ethylvanillin). (Figure presented.).
- Dippe, Martin,Bauer, Anne-Katrin,Porzel, Andrea,Funke, Evelyn,Müller, Anna O.,Schmidt, Jürgen,Beier, Maria,Wessjohann, Ludger A.
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p. 5346 - 5350
(2019/11/29)
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- Synthesis, Crystallization Studies, and in vitro Characterization of Cinnamic Acid Derivatives as SmHDAC8 Inhibitors for the Treatment of Schistosomiasis
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Schistosomiasis is a neglected parasitic disease that affects more than 265 million people worldwide and for which the control strategy relies on mass treatment with only one drug: praziquantel. Based on the 3-chlorobenzothiophene-2-hydroxamic acid J1075, a series of hydroxamic acids with different scaffolds were prepared as potential inhibitors of Schistosoma mansoni histone deacetylase 8 (SmHDAC8). The crystal structures of SmHDAC8 with four inhibitors provided insight into the binding mode and orientation of molecules in the binding pocket as well as the orientation of its flexible amino acid residues. The compounds were evaluated in screens for inhibitory activity against schistosome and human HDACs. The most promising compounds were further investigated for their activity toward the major human HDAC isotypes. The most potent inhibitors were additionally screened for lethality against the schistosome larval stage using a fluorescence-based assay. Two of the compounds showed significant, dose-dependent killing of the schistosome larvae and markedly impaired egg laying of adult worm pairs maintained in culture.
- Bayer, Theresa,Chakrabarti, Alokta,Lancelot, Julien,Shaik, Tajith B.,Hausmann, Kristin,Melesina, Jelena,Schmidtkunz, Karin,Marek, Martin,Erdmann, Frank,Schmidt, Matthias,Robaa, Dina,Romier, Christophe,Pierce, Raymond J.,Jung, Manfred,Sippl, Wolfgang
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p. 1517 - 1529
(2018/08/01)
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- Regioselective enzymatic β-carboxylation of para-hydroxy-styrene derivatives catalyzed by phenolic acid decarboxylases
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Abstract We report on a 'green' method for the utilization of carbon dioxide as C1 unit for the regioselective synthesis of (E)-cinnamic acids via regioselective enzymatic carboxylation of para-hydroxystyrenes. Phenolic acid decarboxylases from bacterial sources catalyzed the β-carboxylation of para-hydroxystyrene derivatives with excellent regio- and (E/Z)-stereoselectivity by exclusively acting at the β-carbon atom of the C=C side chain to furnish the corresponding (E)-cinnamic acid derivatives in up to 40% conversion at the expense of bicarbonate as carbon dioxide source. Studies on the substrate scope of this strategy are presented and a catalytic mechanism is proposed based on molecular modelling studies supported by mutagenesis of amino acid residues in the active site.
- Wuensch, Christiane,Pavkov-Keller, Tea,Steinkellner, Georg,Gross, Johannes,Fuchs, Michael,Hromic, Altijana,Lyskowski, Andrzej,Fauland, Kerstin,Gruber, Karl,Glueck, Silvia M.,Faber, Kurt
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p. 1909 - 1918
(2015/06/02)
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- Synthesis of non-prenyl analogues of baccharin as selective and potent inhibitors for aldo-keto reductase 1C3
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Inhibitors of a human member (AKR1C3) of the aldo-keto reductase superfamily are regarded as promising therapeutics for the treatment of prostatic and breast cancers. Baccharin [3-prenyl-4-(dihydrocinnamoyloxy)cinnamic acid], a component of propolis, was shown to be both potent (Ki56 nM) and highly isoform-selective inhibitor of AKR1C3. In this study, a series of derivatives of baccharin were synthesized by replacing the 3-prenyl moiety with aryl and alkyl ether moieties, and their inhibitory activities for the enzyme were evaluated. Among them, two benzyl ether derivatives, 6m and 6n, showed an equivalent inhibitory potency to baccharin. The molecular docking of 6m in AKR1C3 has allowed the design and synthesis of (E)-3-{3-[(3-hydroxybenzyl)oxy]-4-[(3-phenylpropanoyl)oxy]phenyl}acrylic acid (14) with improved potency (Ki6.4 nM) and selectivity comparable to baccharin. Additionally, 14 significantly decreased the cellular metabolism of androsterone and cytotoxic 4-oxo-2-nonenal by AKR1C3 at much lower concentrations than baccharin.
- Endo, Satoshi,Hu, Dawei,Matsunaga, Toshiyuki,Otsuji, Yoko,El-Kabbani, Ossama,Kandeel, Mahmoud,Ikari, Akira,Hara, Akira,Kitade, Yukio,Toyooka, Naoki
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p. 5220 - 5233
(2014/12/10)
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- Chondroprotective agents
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A chondroprotective agent comprising a carboxylic acid compound of the general formula (I): STR1 wherein R1 and R2 are, independently, a hydrogen atom or an alkyl group of 1 to 6 carbon atoms, or a cis- or trans-isomer thereof, or a pharmaceutically acceptable salt or ester thereof, and a pharmaceutically acceptable carrier is disclosed. The above compound strongly inhibits proteoglycan depletion from the chondrocyte matrix and exhibits a function to protect cartilage, and thus, is extremely effective for the treatment of arthropathy.
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