- Functionalization of photochromic dithienylmaleimides
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Photochromic dithienylmaleimides are well known molecular switches, but for applications the suitable functionalization of the photochromic scaffold is required. We report here synthetic routes to dithienylmaleimides, which are functionalized at three different positions: at each of the thiophene moieties and the maleimide nitrogen. A Perkin-type condensation of two thiophene precursors is used as the key step to assemble the maleimide core, which allows the synthesis of non-symmetrically substituted dithienylmaleimides, such as photochromic amino acids. A different approach to the maleimide core is provided by the reaction of a dithienylmaleic anhydride with amines or hydrazides leading to maleimide protected dithienylmaleimides and photochromic labeled natural amino acids. The photochromic properties of the new photoswitches were investigated showing reversible photochromism in polar organic solvents. This journal is
- Wutz,Falenczyk,Kuzmanovic,K?nig
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p. 18075 - 18086
(2015/03/04)
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- Iron nitrate/TEMPO: A superior homogeneous catalyst for oxidation of primary alcohols to nitriles in air
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A highly practical, one-step, facile synthesis of aromatic, heteroaromatic, allylic and aliphatic nitriles from primary alcohols catalyzed by ferric nitrate [Fe(NO3)3·9H2O] in the presence of TEMPO, aqueous ammonia and air at room temperature is described.
- Dighe, Shashikant U.,Chowdhury, Deepan,Batra, Sanjay
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p. 3892 - 3896
(2015/01/09)
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- Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes
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Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium [(P{(NC 5H10)(C6H11)2}) 2PdCl2] (1) is a highly active and generally applicable C-C cross-coupling catalyst. Apart from its high catalytic activity in Suzuki, Heck, and Negishi reactions, compound 1 also efficiently converted various electronically activated, nonactivated, and deactivated aryl bromides, which may contain fluoride atoms, trifluoromethane groups, nitriles, acetals, ketones, aldehydes, ethers, esters, amides, as well as heterocyclic aryl bromides, such as pyridines and their derivatives, or thiophenes into their respective aromatic nitriles with K4[Fe(CN)6] as a cyanating agent within 24 h in NMP at 140 °C in the presence of only 0.05 mol % catalyst. Catalyst-deactivation processes showed that excess cyanide efficiently affected the molecular mechanisms as well as inhibited the catalysis when nanoparticles were involved, owing to the formation of inactive cyanide complexes, such as [Pd(CN)4]2-, [(CN)3Pd(H)]2-, and [(CN)3Pd(Ar)]2-. Thus, the choice of cyanating agent is crucial for the success of the reaction because there is a sharp balance between the rate of cyanide production, efficient product formation, and catalyst poisoning. For example, whereas no product formation was obtained when cyanation reactions were examined with Zn(CN)2 as the cyanating agent, aromatic nitriles were smoothly formed when hexacyanoferrate(II) was used instead. The reason for this striking difference in reactivity was due to the higher stability of hexacyanoferrate(II), which led to a lower rate of cyanide production, and hence, prevented catalyst-deactivation processes. This pathway was confirmed by the colorimetric detection of cyanides: whereas the conversion of β-solvato-α-cyanocobyrinic acid heptamethyl ester into dicyanocobyrinic acid heptamethyl ester indicated that the cyanide production of Zn(CN)2 proceeded at 25 °C in NMP, reaction temperatures of >100 °C were required for cyanide production with K4[Fe(CN) 6]. Mechanistic investigations demonstrate that palladium nanoparticles were the catalytically active form of compound 1. A balancing act: Compound 1 (see scheme) is a highly active cyanation catalyst. Furthermore, a sharp balance between the rates of cyanide generation, efficient product formation, and catalyst deactivation owing to excess cyanide was observed in deactivation processes. Copyright
- Gerber, Roman,Oberholzer, Miriam,Frech, Christian M.
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supporting information; experimental part
p. 2978 - 2986
(2012/04/04)
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- Hypervalent iodine(III): selective and efficient single-electron-transfer (SET) oxidizing agent
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In 1994, we first determined the single-electron-transfer (SET) oxidation ability of phenyliodine(III) bis(trifluoroacetate) (PIFA) toward phenyl ethers, affording the corresponding aromatic cation radicals. Since then, hypervalent iodine(III) has been utilized as a selective and efficient SET oxidizing agent that enables a variety of direct C-H functionalizations of aromatic rings in electron-rich arenes under mild conditions. We have now extended the original method to work in a series of heteroaromatic compounds such as thiophenes, pyrroles, and indoles. The investigations and results obtained since the start of this century are summarized in this article.
- Dohi, Toshifumi,Ito, Motoki,Yamaoka, Nobutaka,Morimoto, Koji,Fujioka, Hiromichi,Kita, Yasuyuki
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experimental part
p. 10797 - 10815
(2010/03/01)
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- Direct cyanation of heteroaromatic compounds mediated by hypervalent iodine(III) reagents: In situ generation of PhI(III)-CN species and their cyano transfer
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Hypervalent iodine(III) reagents mediate the direct cyanating reaction of a wide range of electron-rich heteroaromatic compounds such as pyrroles 1, thiophenes 3, and indoles 5 under mild conditions (ambient temperature), without the need for any prefunctionalization. Commercially available trimethylsilylcyanide is usable as a stable and effective cyanide source, and the reaction proceeds in a homogeneous system. The N-substituent of pyrroles is crucial to avoid the undesired oxidative bipyrrole coupling process, and thus a cyano group was introduced selectively at the 2-position of N-tosylpyrroles 1 in good yields using the combination of phenyliodine bis(trifluoroacetate) (PIFA), TMSCN, and BF3·Et2O at room temperature. In the reaction mechanism, cation radical intermediates of heteroaromatic compounds are involved as a result of single electron oxidation, and the key to successful transformations seems to depend on the oxidation potential of the substrates used. Thus, the reaction was also successfully extended to other heteroaromatic compounds having oxidation potentials similar to that of N-tosylpyrroles such as thiophenes 3 and indoles 5. However, regioisomeric mixtures of the products derived from the reaction at the 2- and 3-positions were obtained in the case of N-tosylindole 5a. Further investigation performed in our laboratory provided insights into the real active iodine(III) species during the reaction; the reaction is induced by an active hypervalent iodine(III) species having a cyano ligand in situ generated by ligand exchange reaction at the iodine(III) center between trifluoroacetoxy group in PIFA and TMSCN, and effective cyanide introduction into heteroaromatic compounds is achieved by means of the high cyano transfer ability of the hypervalent iodine(III)-cyano intermediates. In fact, the reaction of N-tosylpyrrole 1a with a hypervalent iodine(III)-cyano compound (e.g., (dicyano)iodobenzene 8), in the absence of TMSCN, took place to afford the 2-cyanated product 2a in good yield, and an effective preparation of the intermediates is of importance for successful transformation. 1,3,5,7-Tetrakis[4-{bis(trifluoroacetoxy)-iodo}phenyl]adamantane 12, a recyclable hypervalent iodine(III) reagent, was also comparable in the cyanating reactions as a valuable alternative to PIFA, affording a high yield of the heteroaromatic cyanide by facilitating isolation of the cyanated products with a simple workup. Accordingly, after preparing the active hypervalent iodine(III)-CN species by premixing of a recyclable reagent 12, TMSCN, and BF3· Et2U for 30 min in dichloromethane, reaction of a variety of pyrroles 1 and thiophenes 3 provided the desired cyanated products 2 and 4 in high yields. The iodine compound 13, recovered by filtration after replacement of the reaction solvent to MeOH, could be reused without any loss of activity (the oxidant 12 can be obtained nearly quantitatively by reoxidation of 13 using m-CPBA).
- Dohi, Toshifumi,Morimoto, Koji,Takenaga, Naoko,Goto, Akihiro,Maruyama, Akinobu,Kiyono, Yorito,Tohma, Hirofumi,Kita, Yasuyuki
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p. 109 - 116
(2007/10/03)
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- A facile and clean direct cyanation of heteroaromatic compounds using a recyclable hypervalent iodine(III) reagent
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The facile and clean direct cyanating reaction of pyrroles and thiophenes has been achieved using a recyclable hypervalent iodine(III) reagent 1b by a simple solid-liquid separation of the products and the reagent.
- Dohi, Toshifumi,Morimoto, Koji,Takenaga, Naoko,Maruyama, Akinobu,Kita, Yasuyuki
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p. 1608 - 1610
(2007/10/03)
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- PROCESS FOR PRODUCING AROMATIC NITRILE COMPOUND
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A novel process for industrially producing an aromatic nitrile compound represented by the following general formula (3):characterized in that one of an aromatic hydroxymethyl compound, an aromatic alkoxymethyl compound and an aromatic aldehyde compound, all represented by the following general formula (1): or a mixture thereof is reacted with an oxidized bromine compound represented by the general formula (2)MBrOm in the presence of an acid catalyst and either ammonia or an ammonium sat.
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Page/Page column 23-24
(2008/06/13)
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- Efficacious and orally bioavailable thrombin inhibitors based on a 2,5-thienylamidine at the P1 position: Discovery of N-carboxymethyl-D-diphenylalanyl-L-prolyl[(5-amidino-2- thienyl)methyllamide
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Thrombin, a crucial enzyme in the blood coagulation, has been a target for antithrombotic therapy. Orally active thrombin inhibitors would provide effective and safe prophylaxis for venous and arterial thrombosis. We conducted optimization of a highly efficacious benzamidine-based thrombin inhibitor LB30812 (3, Ki = 3 pM) to improve oral bioavailability. Of a variety of arylamidines investigated at the P1 position, 2,5-thienylamidine effectively replaced the benzamidine without compromising the thrombin inhibitory potency and oral absorption. The sulfamide and sulfonamide derivatization at the N-terminal position in general afforded highly potent thrombin inhibitors but with moderate oral absorption, while the well-absorbable N-carbamate derivatives exhibited limited metabolic stability in S9 fractions. The present work culminated in the discovery of the N-carboxymethyl- and 2,5-thienylamidine-containing compound 22 that exhibits the most favorable profiles of anticoagulant and antithrombotic activities as well as oral bioavilability (Ki = 15 pM; F = 43%, 42%, and 15% in rats, dogs, and monkeys, respectively). This compound on a gravimetric basis was shown to be more effective than a low molecular weight heparin, enoxaparin, in the venous thrombosis models of rat and rabbit. Compound 22 (LB30870) was therefore selected for further preclinical and clinical development.
- Lee, Koo,Park, Cheol Won,Jung, Won-Hyuk,Park, Hee Dong,Lee, Sun Hwa,Chung, Kyung Ha,Park, Su Kyung,Kwon, O. Hwan,Kang, Myunggyun,Park, Doo-Hee,Lee, Sang Koo,Kim, Eunice E.,Yoon, Suk Kyoon,Kim, Aeri
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p. 3612 - 3622
(2007/10/03)
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- Thrombin inhibitors having a lactam at P3
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The present invention provides compounds having a lactam ring at P3 and at P1 have a six-membered heterocyclic ring having two ring nitrogen ring atoms and the remainder of the ring atoms carbon atoms. These compounds have biological activity as active and potent inhibitors of thrombin. Their pharmaceutically acceptable salts, pharmaceutical compositions thereof and methods of using these compounds and pharmaceutical compositions comprising these compounds as therapeutic agents for treatment of disease states in mammals which are characterized by abnormal thrombosis are also described.
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- Non-covalent inhibitors of urokinase and blood vessel formation
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Novel compounds having activity as non-covalent inhibitors of urokinase and having activity in reducing or inhibiting blood vessel formation are provided. These compounds have P1 a group having an amidino or guanidino moiety or derivative thereof. These compounds are useful in vitro for monitoring plasminogen activator levels and in vivo in treatment of conditions which are ameliorated by inhibition of or decreased activity of urokinase and in treating pathologic conditions wherein blood vessel formation is related to a pathologic condition.
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- FUROISOQUINOLINE DERIVATIVES, PROCESS FOR PRODUCING THE SAME AND USE THEREOF
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A compound having a partial structure represented by Formula: or a salt thereof has an excellent phosphodiesterase (PDE) IV-inhibiting effect, and is useful as a prophylactic or therapeutic agent against inflammatory diseases, for example, bronchial asthma, chronic obstructive pulmonary disease (COPD), rheumatoid arthritis, autoimmune disease, diabetes and the like.
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- Novel, potent non-covalent thrombin inhibitors incorporating P3-lactam scaffolds
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Evolution of P1-argininal inhibitor prototypes led to a series of non-covalent P3-7-membered lactam inhibitors 1a-w, featuring novel peptidomimetic units that probe each of the S1, S2, and S3 specificity pockets of thrombin. Rigid P1-arginine surrogates possessing a wide range of basicity (calcd pKa's～neutral-14) were surveyed. The design, synthesis, and biological activity of these targets are presented.
- Ho, Jonathan Z.,Gibson, Tony S.,Semple
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p. 743 - 748
(2007/10/03)
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- Noncovalent tripeptidic thrombin inhibitors incorporating amidrazone, amine and amidine functions at P1
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A series of noncovalent tripeptidic thrombin inhibitors incorporating amidrazone, amine and amidine functions at P1 was investigated. While the amidrazone and the amine series displayed limited oral absorption, the amidine series demonstrated generally good oral absorption and strong antithrombotic activity; the single-digit picomolar Ki achieved from this series is among the best yet reported. The present work highlights the benzamidine compound 11f (LB30812) that exhibits excellent overall profiles of potency, oral absorption and antithrombotic efficacy.
- Lee, Koo,Jung, Won-Hyuk,Park, Cheol Won,Park, Hee Dong,Lee, Sun Hwa,Kwon, O Hwan
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p. 1017 - 1022
(2007/10/03)
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- Non-covalent inhibitors of urokinase and blood vessel formation
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Novel compounds having activity as non-covalent inhibitors of urokinase and having activity in reducing or inhibiting blood vessel formation are provided. These compounds have Pi a group having an amidino or guanidino moiety or derivative thereof. These compounds are useful in vitro for monitoring plasminogen activator levels and in vivo in treatment of conditions which are ameliorated by inhibition of or decreased activity of urokinase and in treating pathologic conditions wherein blood vessel formation is related to a pathologic condition.
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- Potent and efficacious thienylamidine-incorporated thrombin inhibitors
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Novel thrombin inhibitors incorporating thienylamidine at the P1 position were designed and synthesized. These compounds are potent, trypsin- selective and efficacious in the rat model of venous thrombosis. The proposed P1 binding mode in the thrombin active site was confirmed by X-ray crystallographic analysis.
- Lee, Koo,Hwang, Sang Yeul,Yun, Mikyung,Kim, Dong Soo
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p. 1683 - 1686
(2007/10/03)
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