- Palladium-Catalyzed Three-Component Coupling Reaction of o-Bromobenzaldehyde, N-Tosylhydrazone, and Methanol
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A ligand-controlled palladium-catalyzed three-component reaction of o-bromobenzaldehyde, N-tosylhydrazone, and methanol is described. This reaction uses readily available compounds as starting materials while displaying a broad substrate scope and good functional group compatibility.
- Zhu, Lei,Ren, Xiaojian,Yu, Yinghua,Ou, Pengcheng,Wang, Zhi-Xiang,Huang, Xueliang
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p. 2087 - 2092
(2020/03/04)
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- Strategic Approach to the Metamorphosis of γ-Lactones to NH γ-Lactams via Reductive Cleavage and C-H Amidation
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A new approach has elaborated on the conversion of γ-lactones to the corresponding NH γ-lactams that can serve as γ-lactone bioisosteres. This approach consists of reductive C-O cleavage and an Ir-catalyzed C-H amidation, offering a powerful synthetic tool for accessing a wide range of valuable NH γ-lactam building blocks starting from γ-lactones. The synthetic utility was further demonstrated by the late-stage transformation of complex bioactive molecules and the asymmetric transformation.
- Jung, Hoi-Yun,Chang, Sukbok,Hong, Sungwoo
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supporting information
p. 7099 - 7103
(2019/09/07)
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- Controlled photo-flow oxidative reaction (UV-FOR) platform for ultra-fast phthalide and API synthesis
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An integrated photo-flow oxidative reaction (UV-FOR) platform approach is presented for the synthesis of phthalides. The current protocol is catalyst-free, and uses economical and abundant hydro-carbons and hydrocarbon derivatives such as benzoic acid, benzene, and xylene, as starting materials. The reaction is performed using oxygen as a green oxidant in a time- and labour-efficient manner. This integrated approach has been shown to be successful in making a UV-FOR platform suitable for the on-demand synthesis of phthalides and their further syntheses to 2-arylmethylbenzoic acids and arylogous Michael addition products under relatively mild conditions. The current protocol was further extended to the gram scale synthesis of an ischemic stroke-relevant active pharmaceutical ingredient (API), 3-N-butylphthalide (NBP), in a continuous flow process.
- Aand, Dnyaneshwar,Karekar, Sanjeev,Mahajan, Bhushan,Pawar, Amit B.,Singh, Ajay K.
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p. 4584 - 4590
(2018/10/23)
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- Eosin Y as a Redox Catalyst and Photosensitizer for Sequential Benzylic C?H Amination and Oxidation
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A new synergistic multicatalytic activation mode of eosin Y has been discovered by exploiting the redox potential of its ground state and excited state. This catalytic strategy proves to be an enabling tool for visible-light-driven sequential benzylic C?H amination and oxidation of o-benzyl-N-methoxyl-benzamides when using Selectfluor as a hydrogen atom transfer (HAT) reagent and O2 as oxidant. Efficient synthesis of a range of diversely functionalized 3-hydroxyisoindolinones can thus be achieved with good yields and selectivity at mild reaction conditions. Preliminary mechanistic studies and DFT calculations suggest that eosin Y works as a redox catalyst and photosensitizer.
- Yan, Dong-Mei,Zhao, Quan-Qing,Rao, Li,Chen, Jia-Rong,Xiao, Wen-Jing
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p. 16895 - 16901
(2018/10/26)
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- Pd-Catalyzed debenzylation and deallylation of ethers and esters with sodium hydride
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Herein we demonstrate simply that the addition of Pd(OAc)2 as a promotor switches the reactivity of a commonly used base NaH to a nucleophilic reductant. The reactivity is engineered into a palladium-catalyzed reductive debenzylation and deallylation of aryl ethers and esters. This operationally simple, mild protocol displays a broad substrate scope and a broad spectrum of functional group tolerance (>50 examples) and high chemoselectivity toward aryl ethers over aliphatic structures. Moreover, the dual reactivity of NaH as a base and a reductant is demonstrated in efficient synthetic elaboration.
- Mao, Yujian,Liu, Ye,Hu, Yanwei,Wang, Liang,Zhang, Shilei,Wang, Wei
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p. 3016 - 3020
(2018/04/14)
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- Preparation method of carboxylic acid compound
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The invention provides a preparation method of a carboxylic acid compound. The preparation method comprises the following step of taking a lactone component to react with hydrogen in the presence of a compound catalyst to obtain the carboxylic acid compound. The compound catalyst comprises a hydrogenation catalyst and Lewis acid. In the presence of the compound catalyst comprising the hydrogenation catalyst and the Lewis acid, the lactone component is subjected to hydrogenation ring-opening reaction to obtain the carboxylic acid compound. The preparation method has the advantages of moderate reaction conditions and high yield; compared with a traditional method, less byproducts are generated, green and chemical requirements are met and the industrial value is better.
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Paragraph 0113; 0216-0218
(2017/08/29)
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- A Comprehensive Study on Metal Triflate-Promoted Hydrogenolysis of Lactones to Carboxylic Acids: From Synthetic and Mechanistic Perspectives
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Direct hydrogenolysis of lactone to carboxylic acid (i.e., hydrogenolysis of the Calkoxy-O bond with the carbonyl group untouched) is generally difficult, as the current strategies employing Br?nsted acids as the catalyst usually require harsh conditions such as a high temperature and a high H2 pressure. Herein, we report a developed solvent-free catalytic transformation, in which W(OTf)6 is believed to promote the hydrogenolysis process. This strategy could efficiently hydrogenate lactones to carboxylic acids under extra mild conditions (e.g., a reaction temperature of 2) and showed a broad substrate scope. In addition, the catalytic protocol can be further applied to the hydrogenolysis of polyhydroxyalkanoate, as a renewable polymer, to the corresponding straight-chain carboxylic acids. An extensive mechanistic study was subsequently performed, and the density functional theory calculations revealed a reaction pattern, including the complete cleavage of the C=O bond with the assistance of the W(OTf)6 catalyst. Moreover, the key intermediate created in the mechanism, as an oxonium with an OTf moiety, was successfully detected by electrospray ionization mass spectra. Through a comparison with the Br?nsted acid-catalyzed system, the study confirmed that the existence of the OTf moiety can significantly lower the barriers associated with the rearrangement and elimination processes. Meanwhile, emphasis was placed on the critical role that the anion plays, as well as the fact that the anion effect is directly related to the chemoselectivity.
- Zhu, Rui,Jiang, Ju-Long,Li, Xing-Long,Deng, Jin,Fu, Yao
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p. 7520 - 7528
(2017/11/10)
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- Synthesis of annulated arenes and heteroarenes by hydriodic acid and red phosphorus mediated reductive cyclization of 2-(Hetero)aroylbenzoic acids or 3-(Hetero)arylphthalides
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Annulated arenes and hetarenes were prepared in good to very good yields by hydriodic acid/red phosphorus mediated reductive cyclization of 3-(hetero)aryl phthalides. The reductive cyclization also proceeded successfully with 2-aroylbenzoic acids and 2-aroylnaphthoic acids.
- Rafiq, Settu Muhamad,Mohanakrishnan, Arasambattu K.
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supporting information
p. 362 - 370
(2017/02/10)
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- Two-chamber hydrogen generation and application: Access to pressurized deuterium gas
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Hydrogen and deuterium gas were produced and directly applied in a two-chamber system. These gaseous reagents were generated by the simple reaction of metallic zinc with HCl in water for H2 and DCl in deuterated water for D2. The setup proved efficient in classical Pd-catalyzed reductions of ketones, alkynes, alkenes, etc. in near-quantitative yields. The method was extended to the synthesis and isotope labeling of quinoline and 1,2,3,4-tetrahydroquinoline derivatives. Finally, CX-546 and Olaparib underwent efficient Ir-catalyzed hydrogen isotope exchange reactions.
- Modvig, Amalie,Andersen, Thomas L.,Taaning, Rolf H.,Lindhardt, Anders T.,Skrydstrup, Troels
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p. 5861 - 5868
(2014/07/08)
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- Copper-catalyzed benzylic C-H oxygenation under an oxygen atmosphere via N-H imines as an intramolecular directing group
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Copper-catalyzed benzylic C-H oxygenation under an oxygen atmosphere was developed starting from carbonitriles and Grignard reagents via N-H imine intermediates. The present process is characterized by the following two-step sequence in a one-pot manner: (1) addition of Grignard reagents to carbonitriles to form N-H imines and (2) benzylic C-H oxygenation (C=O bond formation) triggered by 1,5-hydrogen atom transfer with transient iminyl copper species.
- Zhang, Line,Ang, Gim Yean,Chiba, Shunsuke
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supporting information; body text
p. 1622 - 1625
(2011/05/05)
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- Muscarinic Receptor Antagonists
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Provided are muscarinic receptor antagonists, which can be useful in treating various diseases of the respiratory, urinary or gastrointestinal system mediated through muscarinic receptors. Also provided are processes for preparing compounds described herein, pharmaceutical compositions comprising compounds described herein, and methods for treating diseases mediated through muscarinic receptors.
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Page/Page column 17-18
(2009/01/23)
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- Tricyclic alkylamides as melatonin receptor ligands with antagonist or inverse agonist activity
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This work reports the design and synthesis of novel alkylamides, characterized by a dibenzo[a,d] cycloheptene nucleus, as melatonin (MLT) receptor ligands. The tricyclic scaffold was chosen on the basis of previous quantitative structure-activity studies on MT1 and MT2 antagonists, relating selective MT2 antagonism to the presence of an aromatic substituent out of the plane of the MLT indole ring. Some dibenzo seven-membered structures were thus selected because of the noncoplanar arrangement of their benzene rings, and an alkylamide chain was introduced to fit the requirements for MLT receptor binding, namely, dibenzocycloheptenes with an acylaminoalkyl side chain at position 10 and dibenzoazepines with this side chain originating from the nitrogen atom bridging the two phenyl rings. Binding affinity at human cloned MT1 and MT2 receptors was measured by 2[125I] iodomelatonin displacement assay and intrinsic activity by the GTPγS test. The majority of the compounds were characterized by higher affinity at the MT2 than at the MT 1 receptor and by very low intrinsic activity values, thus confirming the importance of the noncoplanar arrangement of the two aromatic rings for selective MT2 antagonism. Dibenzocycloheptenes generally displayed higher MT1 and MT2 affinity than dibenzoazepines. N-(8-Methoxy-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-10-ylmethyl)propionamide (4c) and -butyramide (4d) were the most selective MT2 receptor antagonists of the series, with MT2 receptor affinity comparable to that of melatonin and as such among the highest reported in the literature for MLT receptor antagonists. The acetamide derivative 4b produced a noticeable reduction of GTPγS binding at MT2 receptor, thus being among the few inverse agonists described.
- Lucini, Valeria,Pannacci, Marilou,Scaglione, Francesco,Fraschini, Franco,Rivara, Sivia,Mor, Marco,Bordi, Fabrizio,Plazzi, Pier Vincenzo,Spadoni, Gilberto,Bedini, Annalida,Piersanti, Giovanni,Diamantini, Giuseppe,Tarzia, Giorgio
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p. 4202 - 4212
(2007/10/03)
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- Direct Synthesis of γ-Substituted Phthalides Via ortho-Aryl Benzoic Acid Mediated Benzyl Radical Cyclization
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Direct synthesis of γ-substituted phthalids from related ortho-aryl benzoic acids with 48-85% yield are covered. The direct oxidation in the presence of peroxydisulphate-copper (II) chloride in aqueous medium was applied. The reaction is highly regioselective and leads exclusively to γ-butyrolactone, through very stable benzylic radical intermediate.
- Mahmoodi,Salehpour
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p. 875 - 878
(2007/10/03)
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- Direct synthesis of γ-substituted phthalides by cyclization of benzyl radicals generated from o-(arylmethyl)benzoic acids
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Direct oxidation of o-(arylmethyl)benzoic acids with sodium peroxysulfate-copper(II) chloride in water yields γ-substituted phthalides. The reaction is highly regioselective, and the corresponding γ-butyro-lactones are the only products formed through intermediate stable arylmethyl radicals.
- Mahmoodi,Salehpour
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p. 1760 - 1763
(2007/10/03)
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- Reductive cleavage of phthalides with iodotrimethylsilane
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A convenient reductive cleavage of 3-arylphthalides 1 into corresponding 2-benzylbenzoic acids and 2-(2-thienylmethyl)benzoic acid 2 by using iodotrimethylsilane is described.
- Sabitha, Gowravaram,Yadav
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p. 3065 - 3071
(2007/10/03)
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- Chemistry and stereochemistry of benzyl-benzyl interactions in MH+ ions of dibenzyl esters upon chemical ionization and collision-induced dissociation conditions
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Isobutane chemical ionization mass spectra of dibenzyl esters of a wide variety of aliphatic, olefinic, alicyclic and aromatic dicarboxylic acids exhibit abundant m/z 181 C14H13+ ions, indicating a highly general rearrangement process involving the formation of a new bond between the two benzyl groups. An extensive collision-induced dissociation and deuterium labeling study suggested that these ions are an almost equimolar mixture of isomeric α-o-tolylbenzyl, α-p-tolylbenzyl and p-benzylbenzyl cation structures, and this composition is identical for all the diesters examined. This structural assignment of the C14H13 ions suggests a mechanistic pathway for their generation, based on the formation of the new bond between the benzyl methylene group of the protonated benzoxycarbonyl and the phenyl ring of the other ester moiety via π- (and/or ion-neutral) and α-complexes. Stereoisomeric diesters show an unusual steric effect: trans-isomers give rise to much more abundant C14H13+ ions than the cis counterparts. This behavior is explained by stabilized proton-bridged structures of the MH+ ions of the cis-isomers.
- Edelson-Averbukh,Mandelbaum
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p. 515 - 524
(2007/10/03)
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- Reductive Cyclization of Keto Acids to Polycyclic Aromatic Hydrocarbons by Hydroiodic Acid-Red Phosphorus
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Hydroiodic acid-red phosphorus in acetic acid causes ring closure of o-naphthoylbenzoic acids and of o-naphthoylnaphthoic acids to yield benzanthracene and dibenzanthracenes
- Platt, Karl L.,Oesch, Franz
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p. 2601 - 2603
(2007/10/02)
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- 3-Substituted-4-aryl isoquinolines
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3-Substituted-4-aryl isoquinolines, e.g. 3-tertiary butyl-4-phenyl-1,2,3,4-tetrahydroisoquinoline, prepared from corresponding isoquinoline intermediates, are useful as anti-diabetic agents.
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