- A rare cobalt(III) paramagnetic derivative incorporating 1-alkyl-2-[(o-thioalkyl)phenylazo]imidazole (SMeaaiNEt): EPR, redox and magnetic interpretation
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The condensation of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazole (SMeaaiNEt), Co(ClO4)2, 6H2O and NaN3 in methanol affords a rare Co(III) paramagnetic complex [Co(SMeaaiNEt)(N3)3] (1). Single crystal X-ray diffraction study of complex 1 reveals that the Co(III) possesses a distorted octahedral environment. The EPR study interprets an unusual high-spin Co(III) species with configuration t2g4eg2 and S?=?2. The temperature dependent magnetic interpretation agrees with the existence of intermolecular antiferromagnetic coupling on the paramagnetic Co(III) center. A cyclic voltammetry study displays for complex 1 two quasi-reversible and one irreversible responses at the negative direction which may be assigned to different reduction systems. DFT computation using optimized geometry is governed to explain the electronic nature of cobalt derivative which is in accordance with the experimental evidence.
- Nandi, Soumendranath,Das, Kuheli,Datta, Amitabha,Roy, Suman,Garribba, Eugenio,Akitsu, Takashiro,Sinha, Chittaranjan
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Read Online
- Synthesis method of benzo[b] naphtho [2,3-d] thiophene
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The present invention discloses a method for synthesizing benzo [b] naphthio [2,3-d] thiophene, comprising the following steps: 2-aminobenzo [d] thiazole as a raw material, under the action of alkali and haloalkanes, to prepare 2- (methylthio) aniline; using 2- (methylthio) aniline to prepare (2-iophenyl) (methyl) thiane preparation of 1-iodo-2-(methylsulfonyl) benzene; using 1-iodo-2-(methylsulfonyl) benzene; using 1-iodo-2-(methylsulfonyl) Benzene and compound S5 were prepared to obtain 1-(2-(methyl sulfoxide phenyl)) naphthalene, and 1-(2-(methyl sulfoxidephenyl)) naphthalene was used to obtain benzo[b]naphthalene [2,3-d]thiophene. The present invention employs a green route to obtain high yield, high quality benzo [b] naphthalene [2,3-d] thiophene.
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Paragraph 0056-0062; 0103-0106
(2022/03/27)
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- A Mild Heteroatom (O -, N -, and S -) Methylation Protocol Using Trimethyl Phosphate (TMP)-Ca(OH) 2Combination
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A mild heteroatom methylation protocol using trimethyl phosphate (TMP)-Ca(OH)2combination has been developed, which proceeds in DMF, or water, or under neat conditions, at 80 °C or at room temperature. A series of O-, N-, and S-nucleophiles, including phenols, sulfonamides, N-heterocycles, such as 9H-carbazole, indole derivatives, and 1,8-naphthalimide, and aryl/alkyl thiols, are suitable substrates for this protocol. The high efficiency, operational simplicity, scalability, cost-efficiency, and environmentally friendly nature of this protocol make it an attractive alternative to the conventional base-promoted heteroatom methylation procedures.
- Tang, Yu,Yu, Biao
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- Facile syntheses of 3-trifluoromethylthio substituted thioflavones and benzothiophenes via the radical cyclization
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3-CF3S substituted thioflavones and benzothiophenes were achieved via the reactions of AgSCF3 with methylthiolated alkynones and alkynylthioanisoles, respectively, promoted by persulfate. This protocol possesses good functional group tolerance and high yields. Mechanistic studies suggested that a classic two-step radical process was involved, which includes addition of CF3S radical to triple bond and cyclization with SMe moiety.
- Wang, Lu,Wang, Huaiyu,Meng, Weidong,Xu, Xiu-Hua,Huang, Yangen
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supporting information
p. 389 - 392
(2020/03/04)
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- Ionic Reactivity of 2-Isocyanoaryl Thioethers: Access to 2-Halo and 2-Aminobenzothia/Selenazoles
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An ionic cascade insertion/cyclization reaction of thia-/selena-functionalized arylisocyanides has been successfully developed for the efficient and practical synthesis of 2-halobenzothiazole/benzoselenazole derivatives. This synthetic protocol, incorporating a halogen atom when forming the five-membered ring of benzothia/selenazoles, is different from the existing ones, where halogenation of the preformed benzothia/selenazole precursors happens. Additionally, a facile access to 2-aminobenzothiazoles is also achieved by the one-pot cascade reaction of 2-isocyanoaryl thioethers, iodine, and amines.
- Bao, Lan,Dong, Jinhuan,Hu, Junlin,Jia, Mengying,Liu, Xiaoli,Sun, Shaoguang,Xu, Xianxiu
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- Preparation method of o-aminothiophenol
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The invention provides a preparation method of o-aminothiophenol. The preparation method comprises the following steps: putting o-chloronitrobenzene into sodium methyl mercaptide, and performing heating under the action of a catalyst to carry out a methyl vulcanization reaction so as to prepare o-nitrophenyl dimethyl sulfide; putting o-nitrophenyl thioether into a solvent, and carrying out hydrogenation reduction to prepare o-aminobenzene thioether; and demethylating the o-aminothiophenol under the action of hydrobromic acid to obtain the o-aminothiophenol. The preparation method of o-aminothiophenol has the advantages of high yield and high product purity.
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Paragraph 0033; 0038; 0040; 0042; 0044; 0046; 0048; 0052
(2020/12/30)
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- Palladium-Catalyzed 2-(Neopentylsulfinyl)aniline Directed C–H Acetoxylation and Alkenylation of Arylacetamides
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The 2-(neopentylsulfinyl)aniline directing group that promotes rapid palladium-catalyzed C–H acetoxylation and alkenylation of arylacetamides has been developed. The acetoxylation reaches completion within only 40 min at 100 °C and leads to the bis-functionalized products. Alternatively, the reaction can be carried out at room temperature, which is beneficial for sensitive substrates. For the alkenylation, we have developed a protocol in which easily available 1-substituted cyclopropanols were employed as equivalents of vinyl ketones.
- Barysevich, Maryia V.,Laktsevich-Iskryk, Marharyta V.,Krech, Anastasiya V.,Zhabinskii, Vladimir N.,Khripach, Vladimir A.,Hurski, Alaksiej L.
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supporting information
p. 937 - 943
(2020/02/25)
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- Unusually Distorted Pseudo-Octahedral Coordination Environment around CoII from Thioether Schiff Base Ligands in Dinuclear [CoLn] (Ln = La, Gd, Tb, Dy, Ho) Complexes: Synthesis, Structure, and Understanding of Magnetic Behavior
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The synthesis, structural characterization, and magnetic behavior of a new family of binuclear CoII-LnIII complexes of formula [LnIIICoIIL2(NO3)3]·H2O (Ln = La, 1; Gd, 2; Tb, 3; Dy, 4; Ho, 5; HL = 3-methoxy-N-(2-(methylsulfanyl)phenyl)salicylaldimine) have been reported. The chosen ligand system HL has adjacent soft ONS and hard OO binding pockets ideal for selective coordination of CoII and 4f metal ions. All the complexes 1-5 exhibit a CoII center in a highly distorted octahedral geometry with the LnIII centers in bicapped square-antiprism geometry. The unique distortion about the CoII center is introduced by the coordination of 4f metal ions in the hard OO coordination site. The distortion is further supported by the presence of -SMe groups giving an S donor atom which owing to its larger size can support large bond distances and angles. The geometry around the CoII centers is intermediate between meridional and facial geometric isomers. The magnetic properties of these complexes have been investigated by a "full model" approach using CONDON with the experimental magnetochemical analysis revealing ferromagnetic Co-Ln coupling in compounds 2-5. Ab initio calculations on the X-ray crystal structures of 1-5 paint a semiquatitative picture about the contribution of the individual anisotropic centers toward the overall magnetic properties of the compounds. Theoretical analysis predicts 1 and 2 as weak single-ion magnet (SIM) and single-molecule magnet (SMM) respectively with CoII being solely responsible for the complex anisotropy. In 2, JCoGd plays a crucial role in preserving the anisotropy contribution of Co by channelizing relaxation via a higher excited exchange doublet. Because of the inefficiency of JCoTb, JCoDy, and JCoHo in quenching single-ion Ln fragment transverse anisotropy and preserving CoII high axial anisotropy (favoring rhombicity), 3-5 lack SMM behavior.
- Basak, Dipmalya,Leusen, Jan Van,Gupta, Tulika,K?gerler, Paul,Bertolasi, Valerio,Ray, Debashis
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p. 2387 - 2405
(2020/03/05)
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- Copper-Catalyzed Methylthiolation of Aryl Iodides and Bromides with Dimethyl Disulfide in Water
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An efficient route to aryl methyl sulfides through the copper-catalyzed coupling reaction of aryl iodides or bromides with dimethyl disulfide in water is described. Electron-donating and electron-withdrawing functional groups in the substrates were tolerated, and the corresponding products were obtained in moderate to good yields.
- Wang, Ying-Yu,Wu, Xiang-Mei,Yang, Ming-Hua
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supporting information
(2020/07/20)
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- Identification of MsrA homologues for the preparation of (R)-sulfoxides at high substrate concentrations
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Here we report a methionine sulfoxide reductase A (MsrA) homologue with extremely high substrate tolerance and a wide substrate scope for the biocatalytic preparation of enantiopure sulfoxides. This MsrA homologue which was obtained from Pseudomonas alcaliphila (named paMsrA) showed good activity and enantioselectivity towards a series of aryl methyl/ethyl sulfoxides 1a-1k, with electron-withdrawing or electron-donating substituents at the aromatic ring. Chiral sulfoxides in the R configuration were prepared with approximately 50% of yield and up to 99% enantiomeric excess through the asymmetric reductive resolution of racemic sulfoxide catalyzed by the recombinant paMsrA protein. More importantly, kinetic resolution has been successfully accomplished with high enantioselectivity (E > 200) at initial substrate concentrations up to 320 mM (approximately 45 g L-1), which represents a great improvement in the aspect of the substrate concentration for the biocatalytic preparation of chiral sulfoxides.
- Yang, Jiawei,Wen, Yuanmei,Peng, Liaotian,Chan, Yu,Cheng, Xiaoling,Chen, Yongzheng
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p. 3381 - 3388
(2019/04/01)
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- Dual role of ethyl bromodifluoroacetate in the formation of fluorine-containing heteroaromatic compounds
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An efficient one-pot cascade process via unprecedented quadruple cleavage of BrCF2COOEt with primary amines to afford valuable fluorine-containing heterocycles is described, in which BrCF2COOEt plays a dual role as a C1 synthon and a difluoroalkylating reagent for the first time. Mechanistic studies supported by DFT calculations suggest that a base plays an active role in the formation of the key intermediate isocyanides generated in situ from primary amines and difluorocarbene.
- Ma, Xingxing,Mai, Shaoyu,Zhou, Yao,Cheng, Gui-Juan,Song, Qiuling
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supporting information
p. 8960 - 8963
(2018/08/21)
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- Biocatalytic Preparation of Chiral Sulfoxides through Asymmetric Reductive Resolution by Methionine Sulfoxide Reductase A
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Here we report an environmentally friendly method for the preparation of chiral sulfoxides under high substrate concentration using recombinant methionine sulfoxide reductase A from Pseudomonas monteilii (pmMsrA) as a biocatalyst. Our results show that this enzyme can effectively accomplish the preparation of (R)-sulfoxides with approximately 50 % yield and 94–99 % enantiomeric excess through asymmetric reductive resolution of racemic sulfoxide. With the establishment of the enzyme regeneration system, the initial substrate concentration could be increased 40–100 times compared to our original report. The (R)-sulfoxides were obtained with high enantioselectivity under the substrate concentration up to 200 mm (approximately 32 g L?1), representing a quite high substrate concentration in biocatalytic preparation of chiral sulfoxides. Moreover, this system showed fairly good activity and enantioselectivity towards a series of ortho- and para-substituted phenyl methyl sulfoxides under high substrate concentration.
- Peng, Liaotian,Wen, Yuanmei,Chen, Yu,Yuan, Zhimei,Zhou, Yang,Cheng, Xiaoling,Chen, Yongzheng,Yang, Jiawei
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p. 3284 - 3290
(2018/06/04)
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- Iron-Catalyzed Synthesis of Sulfur-Containing Heterocycles
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An iron-catalyzed synthesis of sulfur- and sulfone-containing heterocycles is reported. The method is based on the cyclization of readily available substrates and proceeded with high efficiency and diastereoselectivity. A variety of sulfur-containing heterocycles bearing moieties suitable for subsequent functionalization are prepared. Illustrative examples of such postcyclization modifications are also presented.
- Bosset, Cyril,Lefebvre, Gauthier,Angibaud, Patrick,Stansfield, Ian,Meerpoel, Lieven,Berthelot, Didier,Guérinot, Amandine,Cossy, Janine
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p. 4020 - 4036
(2017/04/27)
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- Developing potential agents against atherosclerosis: Design, synthesis and pharmacological evaluation of novel dual inhibitors of oxidative stress and Squalene Synthase activity
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For the treatment of multifactorial and complex diseases, it has become increasingly apparent that compounds acting at multiple targets often deliver superior efficacy compared to compounds with high specificity for only a single target. Based on previous studies demonstrating the important antioxidant and anti-hyperlipidemic effect of morpholine and 1,4-benzo(x/thi)azine derivatives (A-E), we hereby present the design, synthesis and pharmacological evaluation of novel dual-acting molecules as a therapeutic approach for atherosclerosis. Analogues 1–10 were rationally designed through structural modifications of their parent compounds (A-E) in order for structure-activity relationship studies to be carried out. Most compounds showed a significant inhibition against Squalene Synthase activity exhibiting at the same time a very potent multimodal antioxidant (against lipid peroxidation and as free-radical scavengers) effect, thus bringing to light the 2-aryl-1,4-benzo(x/thia)zin-2-ol scaffold as an outstanding pharmacophore for the design of potent antioxidants. Finally, the replacement of the octahydro-1,4-benzoxazine moiety of lead compound D with its respective 1,4-benzothiazine (compound 4), although conserved (anti-hypercholesterolemic) or even improved (anti-hyperlipidemic) activity, did not preserve the anti-diabetic effect of D.
- Katselou, Maria G.,Matralis, Alexios N.,Kourounakis, Angeliki P.
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p. 748 - 760
(2017/07/22)
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- Investigation of the scope and mechanism of copper catalyzed regioselective methylthiolation of aryl halides Dedicated to Professor Dr. Irina Beletskaya
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Methylthiolation of structurally diverse aryl halides was accomplished under fluoride free conditions using catalytic amounts of CuI, and DMSO as the methylthiolation source. Optimization studies unveiled several varieties of promoters among which Zn(OAc)2 was found ideal. The analogous reaction with DMSO-d6 afforded corresponding deuterated aryl methyl thioether with 99% purity. Mechanistic studies revealed CuSMe as the active methylthiolation agent.
- Joseph, P.J. Amal,Priyadarshini,Kantam, M. Lakshmi,Sreedhar
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p. 8276 - 8283
(2013/09/02)
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- Palladium(II) complexes of terdentate azo ligands with an O,N,S donor set: Synthesis, spectroscopic characterization, X-ray structure and TD-DFT calculations
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The reaction of 2-hydroxy-1-(2′-alkylthiophenylazo)naphthalenes (HL1-HL5) and 1-hydroxy-2-(2′-alkylthiophenylazo) naphthalenes (HL6-HL10) with sodium tetrachloropalladate in ethanol medium at room temperature leads to the formation of a new series of complexes of the type [Pd(L)Cl]. All the palladium compounds have been isolated in their pure form and characterized by spectral and elemental analysis data. The crystal structures of [PdL3Cl] (3) and [PdL6Cl] (6) have been determined by single crystal X-ray diffraction as representative cases. The crystal structures show that both complexes have distorted square-planar structures in which he palladium(II) centers are bonded to O1 of the naphtholato function, N2 of the diazene group and S1 at the 2′ position of the phenyl fragment. Therefore, the ligands bind palladium(II) in a tridentate monoanionic [O, N, S] fashion, which give rise to five- and six-membered chelate rings in each case. The fourth coordination site is occupied by a chloride ion. These complexes show intense absorption bands in the visible and UV region. The nature of the electronic transitions has been examined using (TD-DFT) formalism.
- Acharya, Suvra,Kejriwal, Ambica,Biswas, Achintesh Narayan,Das, Purak,Neogi, Debatra Narayan,Bandyopadhyay, Pinaki
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scheme or table
p. 50 - 57
(2012/07/02)
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- Visible light photocatalytic synthesis of benzothiophenes
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The photocatalytic reaction of o-methylthio-arenediazonium salts with alkynes yields substituted benzothiophenes regioselectively through a radical annulation process. Green light irradiation of eosin Y initiates the photoredox catalysis. The scope of the reaction was investigated by using various substituted diazonium salts and different alkynes.
- Hari, Durga Prasad,Hering, Thea,Koenig, Burkhard
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p. 5334 - 5337,4
(2012/12/12)
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- FeF3/i2-catalyzed synthesis of 4-chalcogen- substituted arylamines by direct thiolation of an arene C-H bond
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An efficient regioselective synthesis of 4-chalcogen-substituted-arylamines by FeF3-catalyzed sulfenylation and selenation of arylamines has been developed. In the presence of FeF3and I2, a variety of arylamines underwent the reaction with disulfides or diselenides to afford the corresponding 4-sulfenyl-or 4-selenenyl-arylamines in moderate to good yields. Georg Thieme Verlag Stuttgart.
- Fang, Xiao-Li,Tang, Ri-Yuan,Zhang, Xing-Guo,Li, Jin-Heng
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experimental part
p. 1099 - 1105
(2011/05/14)
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- Structures, redox behavior, antibacterial activity and correlation with electronic structure of the complexes of nickel triad with 3-(2-(alkylthio) phenylazo)-2,4-pentanedione
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3-(2-(Alkylthio)phenylazo)-2,4-pentanedione (HL), an O, N, S donor ligand, is used for the synthesis of Ni(II), Pd(II) and Pt(II) complexes. The spectroscopic (IR, UV-Vis, and NMR) data determine the structure. The single crystal X-ray diffraction measurement of [Ni(L)2] and [Pt(L)Cl] has confirmed the structures. Coulometric oxidation of [Ni(L)2] and EPR spectra thereof show formation of Ni(III) state. DFT computation has calculated the electronic configuration and has explained the spectral and redox properties of the complexes. The compounds are screened for their in vitro anti-bacterial activity using Gram-positive and Gram-negative bacteria (Bacillus subtilis UC564, Escherichia coli TG1, Staphylococcus aureus Bang25, Pseudomonas aeruginosa C/1/7, Salmonella typhi NCTC62, Salmonella paratyphi NCTC A2, Shigella dysenteriae 8NCTC599/52, Streptococcus faecalis S2, Vibrio cholerae DN7 and Mricococcus luteus AGD1). The minimum inhibitory concentration is determined for the compounds. The effect of the structure of the investigated compounds on the antibacterial activity is discussed.
- Paira, Mrinal Kanti,Mondal, Tapan Kumar,Ojha, Durbadal,Slawin, Alexandra M.Z.,Tiekink, Edward R.T.,Samanta, Amalesh,Sinha, Chittaranjan
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experimental part
p. 175 - 186
(2011/06/24)
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- Copper(II) complexes of thioarylazo-pentanedione: Structures, magnetism, redox properties and correlation with DFT calculations
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Copper(II) complexes of 3-((2-(alkylthio)phenylazo)-2,4-pentanedione, tridentate O, N, S donor ligands, are described in this work. Chloride bridged copper(II) polymers (1) and thiocyanato bridged copper(II) dimmers (2) are characterized by a single crystal X-ray diffraction study. The complexes show antiferromagnetic interactions, with J = -0.5 ± 0.1 cm-1 (1a) and -25.8 ± 0.5 cm-1 (2b), which implies stronger coupling in the -SCN-bridging compound. The spectra, redox and magnetism are explained by DFT studies.
- Paira, Mrinal Kanti,Mondal, Tapan Kumar,López-Torres, Elena,Ribas, Joan,Sinha, Chittaranjan
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experimental part
p. 3147 - 3156
(2011/02/18)
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- An expeditious copper-catalyzed access to 3-aminoquinolinones, 3-aminocoumarins and anilines using sodium azide
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An efficient copper-catalyzedin in situ C-(sp2)-NH2 bond formation to provide a range of 3-aminoquinolin-2(1H)-ones and 3-aminocoumarins from 3-bromoquinolinones and 3-bromocoumarins, respectively, has been achieved. The reaction conditions involve the use of copper powder as the catalyst, eco-friendly ethanol as the solvent in the pres ence of pipecolinic acid as the ligand and ascorbic acid as the additive. The efficiency of this practical method was demonstrated in the synthesis of various anilines.
- Messaoudi, Samir,Brion, Jean-Daniel,Alami, Mouad
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experimental part
p. 1677 - 1687
(2010/10/01)
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- A general and efficient approach to aryl thiols: Cul-catalyzed coupling of aryl iodides with sulfur and subsequent reduction
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A Cul-catalyzed coupling reaction of aryl iodides and sulfur powder takes place in the presence of K2CO3 at 90 °C. The coupling mixture is directly treated with NaBH4 or triphenylphosphine to afford aryl thiols in good to
- Jiang, Yongwen,Qin, Yuxia,Xie, Siwei,Zhang, Xiaojing,Dong, Jinhua,Ma, Dawei
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supporting information; scheme or table
p. 5250 - 5253
(2009/12/28)
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- Mono-N-methylation of functionalized anilines with alkyl methyl carbonates over NaY faujasites. 4. Kinetics and selectivity
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(Chemical Equation Presented) In the presence of NaY faujasite as the catalyst, the reaction of bifunctional anilines (1-4: XC6H 4-NH2; X = OH, CO2H, CH2OH, and CONH2) with methyl alkyl carbonates [MeOCO2R′: R′ = Me or MeO(CH2)2O(CH2)2] proceeds with a very high mono-N-methyl selectivity (XC6H 4NHMe up to 99%), and chemoselectivity as well, with other nucleophilic functions (OH, CO2H, CH2OH, CONH2) fully preserved from alkylation and/or transesterification reactions. Aromatic substituents, however, modify the relative reactivity of amines 1-4: good evidence suggests that, not only steric and electronic effects, but, importantly, direct acid-base interactions between substituents and the catalyst are involved. Weakly acidic groups (OH, CH2OH, CONH2, pKa ≥ 10) may help the reaction, while aminobenzoic acids (pK a of 4-5) are the least reactive substrates. The solvent polarity also affects the reaction, which is faster in xylene than in the more polar diglyme. The mono-N-methyl selectivity is explained by the adsorption pattern of reagents within the zeolite pores: a BAl2 displacement of the amine on methyl alkyl carbonate should occur aided by the geometric features of the NaY supercavities. Different factors account for the reaction chemoselectivity. Evidence proves that the polarizability of the two nucleophilic terms (NH 2 and X groups) of anilines is relevant, although adsorption and confinement phenomena of reagents promoted by the zeolite should also be considered.
- Selva, Maurizio,Tundo, Pietro,Foccardi, Tommaso
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p. 2476 - 2485
(2007/10/03)
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- KF-alumina immobilized in ionic liquids: A novel heterogeneous base for heterocyclization of alkylsulfanylphenylamines into 1,4-benzothiazine
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A rapid and convenient synthetic methodology for the cyclocondensative transformation of various alkylsulfanylphenylamines with bromoacetyl bromide by supporting on KF-alumina in ionic liquids [bmim] [Br] and [bmim][BF 4] has been developed to obtain 3-oxo-1,4-benzothiazine in good yields. The product is easily obtained by extraction with ethyl acetate and concentrating under vacuum. Easy recovery of ionic liquid and use in consecutive reactions is also reported.
- Chhikara, Bhupender S.,Mishra, Anil K.,Tandon, Vibha
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p. 1057 - 1065
(2007/10/03)
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- SUBSTITUTED QUINAZOLINE DERIVATIVES AND THEIR USE AS INHIBITORS
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The use of a compound of formula (I) 1 or a salt, ester or amide thereof; where X is O, or S, S(O) or S(O)2, or NR6 where R6 is hydrogen or C1-6 alkyl,; R5 is an optionally substituted 5-membered heteroaromatic ring, R1, R2 ,R3, R4 are independently selected from various specified moieties, in the preparation of a medicament for use in the inhibition of aurora 2 kinase. Certain compounds are novel and these, together with pharmaceutical compositions containing them are also described and claimed
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- The unexpected formation of a 2,2′-DI(N-ethyl-acetamino)substituted diphenyl disulfane on oxidation of 3-ethyl-2-methylbenzothiazolium tetrafluoroborate
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Attempts at the oxidation of 3-ethyl-2-methylbenzothiazolium salt 2 with a variety of oxidizing reagents did not lead to the desired isochiral S-oxide 3 or achiral S,S-dioxide 4, in some cases, however, unexpectedly to the ring-opened dimeric 2,2′-di(N-ethyl-acetamino)substituted diphenyl disulfane 5, the molecular structure of which was confirmed by x-ray analysis. The synthesis of 2-methylbenzothiazole-S,S-dioxide 14, reported by Zincke et al. in 1915, turned out to be not reproducible.
- Reichardt, Christian,Erfurt, Hans-Peter,Harms, Klaus
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p. 1081 - 1092
(2007/10/03)
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- A new approach to reductive deprotection of thioethers with a low-valent titanium reagent
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Low-valent titanium mediated cleavage of carbon-sulphur bond is reported. This has resulted in an efficient and mild protocol for the deprotection of allyl/benzyl thioethers under reductive condition and with good yields. Deprotection can be performed regio- and chemo-selectively in the presence of acid, ester and N-benzyl/allyl functionalities and is general for aliphatic and aromatic precursors.
- Shadakshari,Talukdar,Chattopadhyay
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p. 1007 - 1010
(2007/10/03)
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- Synthesis, Characterisation and Electrochemistry of Some Stable Ruthenium(II) Complexes of the Bidentate NS Chelating Ligand 1-Amino-2-thiomethylbenzene
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Ruthenium(II) complexes of the bidentate aminothioether ligand, 1-amino-2-thiomethylbenzene (atb), have been synthesised by the direct reaction of atb with different ruthenium-containing starting materials. The complexes are of the type Ru(atb)2X2 [X=Cl (1), X=Br (2)], [Ru(atb)2(PPh3)Cl]Cl (3) and Ru(atb)(bpy)Cl2 (4), and have been characterised by elemental analysis, IR, UV-VIS and NMR spectroscopy. Contrary to the corresponding NiII, PdII, PtII and CuII complexes with the same ligand, these RuII complexes do not suffer demethylation on refluxing in DMF. Their electrochemical behaviour was examined by cyclic voltammetry using a glassy carbon working elctrode and an Ag/AgCl electrode as reference.
- Maji, Milan,Chatterjee, Madhumita,Chattopadhyay, Shyamal Kumar,Ghosh, Saktiprosad
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p. 253 - 257
(2007/10/03)
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- Formation of Sommelet-Hauser-Type Products, 2-Aminoarylmethyl Sulphides, and Nitrenium Ion Products, 2- and 4-Aminoaryl Sulphides, via an N-Arylazasulphonium Salt
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Reactions of a salt (1) formed at -60 deg C from trifluoroacetic anhydride and dimethyl sulphoxide (DMSO) with primary and secondary arylamines gave 2-aminoarylmethyl sulphides (6), (6') and (12) by a Sommelet-Hauser rearrangement of an ylide (5) formed by loss of a methyl proton of an N-arylazasulphonium salt (3) in the absence of base.The use of ethyl methyl sulphoxide instead of DMSO afforded a similar product (19b) by loss of not the ethyl but the methyl proton.However, the use of diethyl sulphoxide merely caused loss of an ethyl group from the N-arylazasulphonium salt to yield ethanesulphenanilide (20).The reaction of (1) with N-phenyl-1-naphthylamine gave mainly aminoaryl sulphides (13) and (14) via an arylnitrenium ion from the N-arylazasulphonium salt.In fact, the reaction of dimethyl sulphide (DMS) with arylnitrenium ions formed in the acid decomposition of aryl azides gave no Sommelet-Hauser-type products but 2- and 4-aminoaryl sulphides (22), (22') and (23).We also discuss the possibility of the N-arylazasulphonium salt being formed by reaction of the arylnitrenium ion with DMS.
- Takeuchi, Hiroshi,Itou, Kazuaki,Murai, Hirotaka,Koyama, Kikuhiko
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p. 3156 - 3188
(2007/10/02)
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- A Convenient and General Synthesis of 2-Aryl- and 2-Pyridyl-3-oxo-3,4-dihydro-2H-1,4-benzothiazines
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The reaction of bis(2-aminophenyl) disulphide 1 with methyl or ethyl aryl- or pyridylacetates and sodium hydride gives the title compounds in good yield and high purity.The reaction is general, the starting materials easily available and the workup is simple and rapid.
- Jacobsen, Niels,Kolind-Andersen, Hans
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p. 911 - 914
(2007/10/02)
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- Alkylation with Oxalic Esters. Scope and Mechanism.
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Alkyl oxalates are well suited for use as standard synthetic reagents in N-, O-, or S-alkylations and often display an interesting regioselectivity.The mechanism seems to be a direct alkylation of the substrate anion.
- Bergman, Jan,Norrby, Per-Ola,Sand, Peter
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p. 6113 - 6124
(2007/10/02)
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- 3-amino-5-methyl-1H-pyrazole-4-carboxylic acids and esters thereof as anticonvulsants, muscle relaxants and anxiolytics
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A novel method of controlling epilepsy, muscle tension, muscular spasticity, and anxiety in living animal bodies by administering compounds of the formula: STR1 wherein: R1 is hydrogen, loweralkyl or a pharmaceutically acceptable cation; R2 and R3, same or different, are hydrogen, loweralkyl, aryl, cycloalkyl, loweralkenyl, 1-adamantyl, heterocyclicaminoalkyl, diloweralkylaminoloweralkyl, or R2 with R3 and adjacent nitrogen may form a heterocyclic ring structure; and the pharmaceutical acceptable acid salts, and tautomeric isomers thereof; and novel pharmaceutical compositions therefor are disclosed.
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- Reaction of Phenylnitrenium Ion with Sulphides. A Novel Synthetic Method for Aminophenyl Sulphide Derivatives
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The reaction of phenyl azide with sulphides in the presence of both trifluoroacetic acid and trifluoromethanesulphonic acid to produce 2- and 4-aminophenyl sulphides (2) and (3) was investigated in order to obtain information on the following points: the kinetics of decomposition of phenyl azide, the effect of addition of benzene to reaction systems, the replacement of phenyl azide by 1-phenyl-2-methyl-4,6-diphenylpyridinium salt, and the steric and electronic effect of substituents in the sulphides.The products are formed through an azasulphonium ion by reaction of phenylnitrenium ion with sulphide, followed by rearrangement of the alkyl group in the azasulphonium ion.Sulphides with primary alykl groups larger than propyl result in selective formation of ortho-products (2), the mechanism of which is discussed in detail.
- Takeuchi, Hiroshi,Hirayama, Shinji,Mitani, Michiharu,Koyama, Kikuhiko
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p. 521 - 528
(2007/10/02)
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- DECOMPOSITION OF ARYLAZIDES BY THF/n-BUTYLLITHIUM-II- -ISOLATION OF 1-ARYL-4,5-DIHYDRO-5-HYDROXY-1H-1,2,3-TRIAZOLES
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By reaction of arylazides having no electron-withdrawing groups with the enolate ion of the acetaldehyde (formed by cycloreversion of THF in the presence of n-buthyllithium), 1-aryl-4,5-dihydro-5-hydroxy-1H-1,2,3-triazoles could be isolated and then characterized.Further reaction of such hydroxytriazolines with the same enolate ion afforded substantial amounts of the corresponding N-formylanilines , confirming their intermediacy in the previously reported decomposition of arylazides by THF/n-butyllithium.On the other hand, using alkoxides as bases, the preferred scheme of conversion of the hydroxytriazolines was found to be the known dehydration to 1-aryl-1H-1,2,3-triazoles.
- Nunno, L. Di,Scilimati, A.
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p. 3913 - 3920
(2007/10/02)
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- Pyrolyses of o-Alkoxy- and o-Alkylthio-N-Allylanilines and of Some Related O- and S-Allyl Compounds
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The o-substituted allyl compounds (1)-(12) have been pyrolysed in order to generate aminyl, phenoxyl, and thiophenoxyl radicals with adjacent substituents.In all cases, products are formed by intramolecular hydrogen transfer from the substituent to the radical centre.This process may be followed by rearrangement to give an aldehyde, by heteroatom extrusion to give an alkene, or by ring formation to give five-membered ring heterocycles (Scheme 1, routes A, B1, and B2 respectively.The distribution of products formed by each route is dependent both on the nature of the o-substituent, and on the nature of the initial radical.
- Cadogan, J. I. G.,Hickson, Clare L.,McNab, Hamish
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p. 1885 - 1890
(2007/10/02)
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- DECOMPOSITION OF ARILAZIDES AND P-TOSYLAZIDE BY THF/n-BUTYLLITHIUM. A NEW SOURCE OF DIAZOMETHANE
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Variously substituted arylazides, as well as p-tosylazide, when allowed to react at room temperature with THF previously treated with n-butyllithium, undergo a rapid decomposition affording the corresponding amines and formamides, together with diazomethane.This diazo transfer (with deformylation) reaction is thought to involve the enolate of the acetaldehyde generated by the known cycloreversion of THF in the presence on n-butyllithium.
- Babudri, F.,Di Nunno, L.,Florio, S.,Valzano, S.
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p. 1731 - 1736
(2007/10/02)
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- 4-Amino-3-quinolinecarboxylic acids and esters-antisecretory anti-ulcer compounds
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A method of reducing gastric acidity and treating peptic ulcers and pharmaceutical compositions therefor with certain 4-amino-3-quinolinecarboxylic acids and esters are disclosed. Illustrative of compounds useful in the method which relies on activity as antisecretory activity is the novel compound ethyl 8-methoxy-4-[(2-methylphenyl)amino]-3-quinolinecarboxylate which has the formula: STR1
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