- Amino Acids: Nontoxic and Cheap Alternatives for Amines for the Synthesis of Benzoxazoles through the Oxidative Functionalization of Catechols
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The nano magnetic Fe3O4 (NM?Fe3O4) was applied for the synthesis of benzoxazoles via a C(aryl)?OH functionalization of catechol derivatives and amines in ethanol at room temperature. In the next step, amino acids have been applied as nontoxic and cheap alternatives for amines. The obtained products were similar with the regular amines case. This is the first report about the application of amino acids as alternatives for primary amines in organic synthesis. Furthermore, the presented method was successfully applied toward the synthesis of desired products in large scales. (Figure presented.).
- Aberi, Mahdi,Aboonajmi, Jasem,Sharghi, Hashem,Shekouhy, Mohsen
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p. 1064 - 1083
(2020/01/24)
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- METHODS AND COMPOSITIONS FOR MODULATING SPLICING
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Described herein are small molecule splicing modulator compounds that modulate splicing of mRNA, such as pre-mRNA, encoded by genes, and methods of use of the small molecule splicing modulator compounds for modulating splicing and treating diseases and conditions.
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Paragraph 0620; 0655
(2020/08/22)
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- Pd-Catalyzed Cross-Coupling Reactions Promoted by Biaryl Phosphorinane Ligands
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We report the use of biaryl phosphorinanes as ligands for Pd-catalyzed cross-coupling reactions. A modular synthesis was developed that employs a double conjugate addition of primary biaryl phosphines into 1,1,5,5-tetraalkyl penta-1,4-diene-3-ones. Notably, this synthesis does not require the use of copper, a known contaminant in structurally related biaryl phosphane ligands. Using the synthetic strategy described above, we synthesized a library of biaryl phosphorinanes, varying their substitution about phosphorus and the steric and electronic nature of the biaryl motif. We then benchmarked their performance as ligands in Pd-catalyzed cross coupling reactions such as aryl sulfonamidation, aryl alkoxylation, and aryl amination in the presence of soluble organic bases. In each reaction studied, many ligands outperformed biaryl phosphanes known to promote the given transformation. Detailed substrate scopes were determined using high-throughput screening technology. Several biaryl phosphorinanes and their corresponding Pd(II) oxidative-addition complexes were extensively characterized using NMR spectroscopy and X-ray crystallography. General observations support that biaryl phosphorinanes promote reductive elimination and form robust catalysts with palladium. In many cases the use of these biaryl phosphorinanes may be advantageous over the use of biaryl phosphanes with respect to lower catalyst loadings, shorter reaction times, and robustness.
- Laffoon, Joshua D.,Chan, Vincent S.,Fickes, Michael G.,Kotecki, Brian,Ickes, Andrew R.,Henle, Jeremy,Napolitano, José G.,Franczyk, Thaddeus S.,Dunn, Travis B.,Barnes, David M.,Haight, Anthony R.,Henry, Rodger F.,Shekhar, Shashank
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p. 11691 - 11708
(2019/12/02)
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- Utility of Nitrogen Extrusion of Azido Complexes for the Synthesis of Nitriles, Benzoxazoles, and Benzisoxazoles
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The utility of the nitrogen extrusion reaction of azido complexes, generated in situ from the corresponding aldehydes or ketones with TMSN3 in the presence of ZrCl4 or TfOH, has been described. These azido complexes could undergo three different pathways, depending on the substrates. First, azido methanolate complexes or imine diazonium ions could lead to benzisoxazole products via an intramolecular nucleophilic substitution. Second, imine diazonium ions could also undergo either the elimination of proton to provide nitrile products in good to excellent yields or an aryl migration, followed by an intramolecular nucleophilic addition, to give benzoxazole products in good yields.
- Nimnual, Phongprapan,Tummatorn, Jumreang,Thongsornkleeb, Charnsak,Ruchirawat, Somsak
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p. 8657 - 8667
(2015/09/15)
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- Synthesis of benzoxazoles from 2-aminophenols and β-diketones using a combined catalyst of br?nsted acid and copper iodide
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Cyclization reactions of 2-aminophenols with β-diketones catalyzed by a combination of Br?nsted acid and CuI are presented. Various 2-substituted benzoxazoles were obtained through these reactions. Different substituents such as methyl, chloro, bromo, nitro, and methoxy on 2-aminophenol are tolerated under the optimized reaction conditions.
- Mayo, Muhammad Shareef,Yu, Xiaoqiang,Zhou, Xiaoyu,Feng, Xiujuan,Yamamoto, Yoshinori,Bao, Ming
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p. 6310 - 6314
(2014/07/21)
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- Iridium-catalyzed C-H borylation of heteroarenes: Scope, regioselectivity, application to late-stage functionalization, and mechanism
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A study on the iridium-catalyzed C-H borylation of heteroarenes is reported. Several heteroarenes containing multiple heteroatoms were found to be amenable to C-H borylation catalyzed by the combination of an iridium(I) precursor and tetramethylphenanthroline. The investigations of the scope of the reaction led to the development of powerful rules for predicting the regioselectivity of borylation, foremost of which is that borylation occurs distal to nitrogen atoms. One-pot functionalizations are reported of the heteroaryl boronate esters formed in situ, demonstrating the usefulness of the reported methodology for the synthesis of complex heteroaryl structures. Application of this methodology to the synthesis and late-stage functionalization of biologically active compounds is also demonstrated. Mechanistic studies show that basic heteroarenes can bind to the catalyst and alter the resting state from the olefin-bound complex observed during arene borylation to a species containing a bound heteroarene, leading to catalyst deactivation. Studies on the origins of the observed regioselectivity show that borylation occurs distal to N-H bonds due to rapid N-H borylation, creating an unfavorable steric environment for borylation adjacent to these bonds. Computational studies and mechanistic studies show that the lack of observable borylation of C-H bonds adjacent to basic nitrogen is not the result of coordination to a bulky Lewis acid prior to C-H activation, but the combination of a higher-energy pathway for the borylation of these bonds relative to other C-H bonds and the instability of the products formed from borylation adjacent to basic nitrogen.
- Larsen, Matthew A.,Hartwig, John F.
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supporting information
p. 4287 - 4299
(2014/04/03)
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- Mild and general palladium-catalyzed synthesis of methyl aryl ethers enabled by the use of a palladacycle precatalyst
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A general method for the Pd-catalyzed coupling of methanol with (hetero)aryl halides is described. The reactions proceed under mild conditions with a wide range of aryl and heteroaryl halides to give methyl aryl ethers in high yield.
- Cheung, Chi Wai,Buchwald, Stephen L.
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supporting information
p. 3998 - 4001
(2013/09/02)
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- Synthesis of substituted 2-heteroarylbenzazol-5-ol derivatives as potential ligands for estrogen receptors
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Exposure to estrogen is associated with increased risk of breast and other types of human cancer. One therapeutic goal would be the creation of new molecules that would retain hormonal potency while incorporating features to retard or prevent quinone toxicity. Hence, new structures closely related to ERB-041, a known ERβ selective agonist, were synthesized whereas the phenol ring is substituted with non-quinone forming rings such as pyrazole, 2-pyrimidine-2(1H)-one or pyridine-2(1H)-one. 2-Methyl-5-methoxy-1,3- benzoxazoles (or 1,3-benzothiazole) are key intermediates for the production of the pyrazole and pyrimidine-2(1H)-one analogs. The required 1,3-benzoxazoles were synthesized starting from reduction of 2-nitro-4-methoxyphenols, followed by condensation with trimethyl orthoacetate. Then, the diiminium perchlorate intermediates were prepared from the latter compounds by Vilsmeier-Haack reaction. The reaction of the resulting intermediates with hydrazine hydrate and guanidium chloride afforded the title pyrazole and pyrimidine-2(1H)-ones, respectively. The pyridine analogs were synthesized starting from the reaction of 2-amino-4-methoxyphenols with 6-bromopyridine-3-carboxaldehyde followed by oxidation with DDQ to afford bromopyridines. These compounds were next treated with benzyl alcohol in the presence of potassium tert-butoxide to afford 2-benzyloxypyridine, which in subsequent dealkylation with boron tribromide produced the title pyridine-2-(1H)-ones.
- Rezazadeh, Sina,Navidpour, Latifeh,Shafiee, Abbas
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p. 6076 - 6082
(2013/07/19)
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- A divergent and selective synthesis of isomeric benzoxazoles from a single N-Cl imine
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A divergent and regioselective synthesis of either 3-substituted benzisoxazoles or 2-substituted benzoxazoles from readily accessible ortho-hydroxyaryl N-H ketimines is described. The reaction proceeds in two distinct pathways through a common N-Cl imine intermediate: (a) N-O bond formation to form benzisoxazole under anhydrous conditions and (b) NaOCl mediated Beckmann-type rearrangement to form benzoxazole, respectively. The reaction path also depends on the electronic nature of the aromatic ring, with the electron-rich aromatic rings favoring the rearrangement and the electron-deficient rings favoring the N-O bond formation. A Beckmann-type rearrangement mechanism via net [1,2]-aryl migration for the formation of 2-substituted benzoxazole is proposed.
- Chen, Cheng-Yi,Andreani, Teresa,Li, Hongmei
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supporting information; experimental part
p. 6300 - 6303
(2012/01/05)
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- Indium-mediated one-pot synthesis of benzoxazoles or oxazoles from 2-nitrophenols or 1-aryl-2-nitroethanones
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One-pot reduction-triggered heterocyclizations from 2-nitrophenols to benzoxazoles and from 1-aryl-2-nitroethanones to oxazoles were investigated. In the presence of indium/AcOH in benzene at reflux, 2-nitrophenols and R-C(OMe)3 (R=H, Me, Ph) produced excellent yields of corresponding benzoxazoles within an hour. Similarly, 1-aryl-2-nitroethanones and Ph-C(OMe)3 in the presence of indium/AcOH in acetonitrile transformed into the corresponding oxazoles with good yields.
- Lee, Jung June,Kim, Jihye,Jun, Young Moo,Lee, Byung Min,Kim, Byeong Hyo
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experimental part
p. 8821 - 8831
(2009/12/26)
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- Heteroaryl alkyl piperazine derivatives
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Novel compounds of the general formula: and pharmaceutically acceptable acid addition salts thereof, wherein the compounds are useful in therapy to protect skeletal muscles against damage resulting from trauma or to protect skeletal muscles subsequent to muscle or systemic diseases such as intermittent claudication, to treat shock conditions, to preserve donor tissue and organs used in transplants, in the treatment of diabetes, in the treatment of cardiovascular diseases including atrial and ventricular arrhythmias, Prinzmetal's (variant) angina, stable angina, and exercise induced angina, congestive heart disease, and myocardial infarction.
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- Novel synthesis of benzoxazoles from o-nitrophenols and amines
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o-Nitrophenols and o-nitroaniline were reacted with amines at 210-215°C to produce the corresponding benzoxazoles and benzimidazoles, respectively, in moderate yields. The reactions between o-nitrophenols containing a CO2Me or OMe group on their benzene rings and N,N-diethylaniline were examined to investigate the effects of the position and electronic character of these substituents on the formation of the oxazole ring.
- Nishioka, Hiromi,Ohmori, Yukiko,Iba, Yumiko,Tsuda, Eri,Harayama, Takashi
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p. 193 - 198
(2007/10/03)
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- Heteroaryl alkyl piperazine derivatives
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Novel compounds of the general formula: and pharmaceutically acceptable acid addition salts thereof, wherein the compounds are useful in therapy to protect skeletal muscles against damage resulting from trauma or to protect skeletal muscles subsequent to muscle or systemic diseases such as intermittent claudication, to treat shock conditions, to preserve donor tissue and organs used in transplants, in the treatment of diabetes, in the treatment of cardiovascular diseases including atrial and ventricular arrhythmias, Prinzmetal's (variant) angina, stable angina, and exercise induced angina, congestive heart disease, and myocardial infarction.
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- Heteroaryl alkyl piperazine derivatives
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Novel compounds of the general formula: and pharmaceutically acceptable acid addition salts thereof, wherein the compounds are useful in therapy to protect skeletal muscles against damage resulting from trauma or to protect skeletal muscles subsequent to muscle or systemic diseases such as intermittent claudication, to treat shock conditions, to preserve donor tissue and organs used in transplants, in the treatment of cardiovascular diseases including atrial and ventricular arrhythmias, Prinzmetal's (variant) angina, stable angina, and exercise induced angina, congestive heart disease, and myocardial infarction.
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- Carbon-carbon bond cleavage of diynes through the hydroamination with transition metal catalysts
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The C-C bond cleavage of terminal and internal diynes takes place readily in the presence of catalytic amounts of Ru3(CO)12 or Pd(NO3)2 and of 2-aminophenol, giving the corresponding benzoxazoles and ketones in good to high yields. There are two different modes of the bond cleavage: (a) an alkyne C-C triple bond is cleaved, and (b) the C-C single bond between the two alkyne groups is cleaved. Copyright
- Shimada, Tomohiro,Yamamoto, Yoshinori
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p. 6646 - 6647
(2007/10/03)
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