- Molecular chameleons . Design and synthesis of C-4-substituted imidazole fleximers
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(Chemical Equation Presented) The synthesis of two flexible nucleosides is presented. The fleximers feature the purine ring system split into its imidazole and pyrimidine components. This modification serves to introduce flexibility to the nucleoside while still retaining the elements essential for molecular recognition. As a result, these structurally innovative nucleosides can more readily adapt to capricious binding sites and, as such, should find use for investigating enzyme-coenzyme as well as nucleic acid-protein interactions.
- Seley, Katherine L.,Salim, Samer,Zhang, Liang
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- Iodonitrene in Action: Direct Transformation of Amino Acids into Terminal Diazirines and 15N2-Diazirines and Their Application as Hyperpolarized Markers
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A one-pot metal-free conversion of unprotected amino acids to terminal diazirines has been developed using phenyliodonium diacetate (PIDA) and ammonia. This PIDA-mediated transformation occurs via three consecutive reactions and involves an iodonitrene intermediate. This method is tolerant to most functional groups found on the lateral chain of amino acids, it is operationally simple, and it can be scaled up to provide multigram quantities of diazirine. Interestingly, we also demonstrated that this transformation could be applied to dipeptides without racemization. Furthermore, 14N2 and 15N2 isotopomers can be obtained, emphasizing a key trans-imination step when using 15NH3. In addition, we report the first experimental observation of 14N/15N isotopomers directly creating an asymmetric carbon. Finally, the 15N2-diazirine from l-tyrosine was hyperpolarized by a parahydrogen-based method (SABRE-SHEATH), demonstrating the products' utility as hyperpolarized molecular tag.
- Colell, Johannes F. P.,Franck, Xavier,Glachet, Thomas,Marzag, Hamid,Reboul, Vincent,Saraiva Rosa, Nathalie,Theis, Thomas,Warren, Warren S.,Zhang, Guannan
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- Synthesis of α-aminonitriles using aliphatic nitriles, α-amino acids, and hexacyanoferrate as universally applicable non-toxic cyanide sources
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In cyanation reactions, the cyanide source is often directly added to the reaction mixture, which restricts the choice of conditions. The spatial separation of cyanide release and consumption offers higher flexibility instead. Such a setting was used for the cyanation of iminium ions with a variety of different easy-to-handle HCN sources such as hexacyanoferrate, acetonitrile or α-amino acids. The latter substrates were first converted to their corresponding nitriles through oxidative decarboxylation. While glycine directly furnishes HCN in the oxidation step, the aliphatic nitriles derived from α-substituted amino acids can be further converted into the corresponding cyanohydrins in an oxidative C-H functionalization. Mn(OAc)2 was found to catalyze the efficient release of HCN from these cyanohydrins or from acetone cyanohydrin under acidic conditions and, in combination with the two previous transformations, permits the use of protein biomass as a non-toxic source of HCN.
- Nauth, Alexander M.,Konrad, Tim,Papadopulu, Zaneta,Vierengel, Nina,Lipp, Benjamin,Opatz, Till
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supporting information
p. 4217 - 4223
(2018/09/29)
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- Corresponding amine nitrile and method of manufacturing thereof
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The invention relates to a manufacturing method of nitrile. Compared with the prior art, the manufacturing method has the characteristics of significantly reduced using amount of an ammonia source, low environmental pressure, low energy consumption, low production cost, high purity and yield of a nitrile product and the like, and nitrile with a more complex structure can be obtained. The invention also relates to a method for manufacturing corresponding amine from nitrile.
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Paragraph 0153; 0154; 0155; 0166; 0167
(2018/05/07)
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- Synthetic method of histamine dichloride
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The invention discloses a synthetic method of histamine dichloride, and belongs to the field of drug synthesis. The synthetic method comprises the following steps: preparing a cyano methylimidazole intermediate through oxidization of TCCA (Trichloroisocyanuric Acid) under an alkaline condition by taking L-histidine as an original raw material, and then preparing medicinal histamine dichloride through catalytic hydrogenation and one-step salifying process. In the histamine dichloride compounded through the synthetic method, the content of related substances is less than 0.5 percent, the content of a single impurity is less than 0.1 percent, and the histamine dichloride accords with medicinal level. A reagent adopted by the technology is cheap and of low-toxicity, the reaction is safe and reliable, an alcohol solvent can be recycled, after-treatment operation is simple and convenient, and the technology is environment-friendly and is beneficial for large-scale industrial production.
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Paragraph 0008; 0012
(2017/03/24)
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- Discovery of α-Substituted Imidazole-4-acetic Acid Analogues as a Novel Class of ρ1γ-Aminobutyric Acid Type A Receptor Antagonists with Effect on Retinal Vascular Tone
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The ρ-containing γ-aminobutyric acid type A receptors (GABAARs) play an important role in controlling visual signaling. Therefore, ligands that selectively target these GABAARs are of interest. In this study, we demonstrate that the partial GABAAR agonist imidazole-4-acetic acid (IAA) is able to penetrate the blood–brain barrier in vivo; we prepared a series of α- and N-alkylated, as well as bicyclic analogues of IAA to explore the structure–activity relationship of this scaffold focusing on the acetic acid side chain of IAA. The compounds were prepared via IAA from l-histidine by an efficient minimal-step synthesis, and their pharmacological properties were characterized at native rat GABAARs in a [3H]muscimol binding assay and at recombinant human α1β2γ2Sand ρ1GABAARs using the FLIPR membrane potential assay. The (+)-α-methyl- and α-cyclopropyl-substituted IAA analogues ((+)-6 a and 6 c, respectively) were identified as fairly potent antagonists of the ρ1GABAAR that also displayed significant selectivity for this receptor over the α1β2γ2SGABAAR. Both 6 a and 6 c were shown to inhibit GABA-induced relaxation of retinal arterioles from porcine eyes.
- Krall, Jacob,Brygger, Benjamin M.,Sigureardóttir, Sara B.,Ng, Clarissa K. L.,Bundgaard, Christoffer,Kehler, Jan,Nielsen, Birgitte,Bek, Toke,Jensen, Anders A.,Fr?lund, Bente
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p. 2299 - 2310
(2016/10/25)
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- Highly potent geminal bisphosphonates. From pamidronate disodium (Aredia) to zoledronic acid (Zometa)
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Bisphosphonates (BPs) are pyrophosphate analogues in which the oxygen in P-O-P has been replaced by a carbon, resulting in a metabolically stable P-C-P structure. Pamidronate (1b, Novartis), a second-generation BP, was the starting point for extensive SAR studies. Small changes of the structure of pamidronate lead to marked improvements of the inhibition of osteoclastic resorption potency. Alendronate (1c, MSD), with an extra methylene group in the N-alkyl chain, and olpadronate (1h, Gador), the N,N-dimethyl analogue, are about 10 times more potent than pamidronate. Extending one of the N-methyl groups of olpadronate to a pentyl substituent leads to ibandronate (1k, Roche, Boehringer-Mannheim), which is the most potent close analogue of pamidronate. Even slightly better antiresorptive potency is achieved with derivatives having a phenyl group linked via a short aliphatic tether of three to four atoms to nitrogen, the second substituent being preferentially a methyl group (e.g., 4g, 4j, 5d, or 5r). The most potent BPs are found in the series containing a heteroaromatic moiety (with at least one nitrogen atom), which is linked via a single methylene group to the geminal bisphosphonate unit. Zoledronic acid (6i), the most potent derivative, has an ED50 of 0.07 mg/kg in the TPTX in vivo assay after sc administration. It not only shows by far the highest therapeutic ratio when comparing resorption inhibition with undesired inhibition of bone mineralization but also exhibits superior renal tolerability. Zoledronic acid (6i) has thus been selected for clinical development under the registered trade name Zometa. The results of the clinical trials indicate that low doses are both efficacious and safe for the treatment of tumor-induced hypercalcemia, Paget's disease of bone, osteolytic metastases, and postmenopausal osteoporosis.
- Widler, Leo,Jaeggi, Knut A.,Glatt, Markus,Müller, Klaus,Bachmann, Rolf,Bisping, Michael,Born, Anne-Ruth,Cortesi, Reto,Guiglia, Gabriela,Jeker, Heidi,Klein, Rémy,Ramseier, Ueli,Schmid, Johann,Schreiber, Gerard,Seltenmeyer, Yves,Green, Jonathan R.
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p. 3721 - 3738
(2007/10/03)
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- KINETICS OF OXIDATION OF AMINO ACIDS BY QUINOLINIUM DICHROMATE
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The kinetics of oxidation of amino acids (lysine, arginine and histidine) by quinolinium dichromate, in acid medium, at constant ionic strength, has been investigated.The reactions were first order each in substrate, oxidant and acid concentrations.Under the experimental conditions used, the reaction proceeded by the way of the cationic form of the amino acids.The absence of a kinetic isotope effect indicated that there was no cleavage of the carbon-hydrogen bond in the rate determining step.
- Karim, E.,Mahanti, M. K.
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p. 1471 - 1476
(2007/10/02)
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- Kinetics of Oxidation of Histidine by N-Chlorobenzamide in Aqueous Methanol
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Oxidation of histidine by N-chlorobenzamide (NCB) in methanol-water mixture (20percent, v/v) in the presence of HClO4 and NaCl is first order each in , and .The order in is always zero.Salt and solvent effects are only marginal.Added benzamide has only a little retarding influence.Based on these observations a suitable mechanism has been proposed.
- Anjali Lal,Agrawal, M. C.
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p. 696 - 697
(2007/10/02)
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- Chloraminometric Reactions: Kinetics and Mechanisms of Oxidations of Amino-acids by Sodium N-Chlorotoluene-p-sulphonamide in Acid and Alkaline Media
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Available data on the kinetics of oxidations of amino-acids by sodium N-chloro toluene-p-sulphonamide (chloramine T) in acid and alkaline media have been critically examined.General mechanisms have been proposed for both acid and alkaline medium oxidations.The oxidation process in acid media has been shown to proceed via two paths, one involving the direct interaction of N-chlorotoluene-p-sulphonamide (RNHCl) with the neutral amino-acid in a slow step leading to the formation of the monochloroamino-acid which subsequently interacts with another molecule of RNHCl, in a fast step, to give the NN-dichloroamino-acid which in turn undergoes molecular rearrangement and elimination to yield the products, and the other involving the interaction of Cl2 or H2OCl(1+), produced from the disproportionation of RNHCl in the presence or absence of Cl(1-), with the substrate to give the products.In the alkaline medium mechanisms involving the interaction of RNHCl, HOCl, RNCl(1-), and OCl(1-) with the substrate are proposed.The mechanisms proposed and the derived rate lows are consistent with the observed kinetics.The rate constants predicted by the derived rate laws, as the concentrations of substrate and Cl(1-) ion change, are in excellent agreement with the observed rate constants thus further verifying the rate laws and hence the proposed mechanisms.
- Gowda, Basavalinganadoddy Thimme,Mahadevappa, Darndinasivara S.
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p. 323 - 334
(2007/10/02)
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- Kinetic and Mechanistic Studies of Oxidation of Arginine and Histidine by Sodium N-Chloro-4-methylbenzenesulphonamide (Chloramine T) in Hydrochloric Acid Medium
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Kinetics of oxidation of arginine and histidine by chloramine T (CAT) in HCl medium has been studied at 30 deg C.At low acid concentrations (0.04-0.12M), simultaneous catalysis by H(+) and Cl(-) ions is noted conforming to mixed rate laws (i) and (ii). .Ionic strength and addition of the product p-toluenesulphonamide has no effect on the rate.Addition of methanol decreases the rate.Activation parameters have been evaluated. -d/dt = k'' + k'''0.6 ..(i), -d/dt = k'' + k'''0.6 ..(ii).Ionic strength and addition of the reaction product p-toluenesulphonamide has no effect on the rate.Addition of methanol decreases the rate.Activation parameters have been evaluated.At higher (>/= 0.12M), the rate law for both the amino acids becomes, -d/dt = k0.6.A positive methanol effect is noticed.Mechanisms consistent with the observed rate laws have been proposed.
- Mahadevappa, D. S.,Rangappa, K. S.,Gowda, N. M. M.
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p. 263 - 268
(2007/10/02)
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