- Synthesis and oxidation-induced DNA cross-linking capabilities of bis(catechol) quaternary ammonium derivatives
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A study was conducted to demonstrate the synthesis of a number of DNA crosslinking agents, such as bis(catechol) quaternary ammonium derives. It was found that these agents can crosslink DNA through an o-quinone intermediate, induced by oxidation. It was also found that these compounds are composed of two catechol monomers, acting as DNA cross-linking units and are joined by different linkers that act as DNA binding units. Positive charged linkers and quaternary ammonium derivatives were used in the study, to achieve high affinity to DNA. Aliphatic and aromatic chains were investigated, to determine their ability in performing favorable cross-linking reactions and to determine the relationship between agent flexibility and DNA cross-linking abilities.
- Song, Zhibin,Weng, Xiaocheng,Weng, Liwei,Huang, Jing,Wang, Xiaolin,Bai, Minghui,Zhou, Yangyang,Yang, Guangfu,Zhou, Xiang
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- Palladium-Catalyzed Reductive Aminocarbonylation of Benzylammonium Triflates with o-Nitrobenzaldehydes for the Synthesis of 3-Arylquinolin-2(1 H)-ones
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A palladium-catalyzed straightforward procedure for the synthesis of 3-arylquinolin-2(1H)-ones has been developed. The synthesis proceeds through a palladium-catalyzed reductive aminocarbonylation reaction of benzylic ammonium triflates with o-nitrobenzaldehydes, and a wide range of 3-arylquinolin-2(1H)-ones was obtained in moderate to good yields with very good functional group compatibility.
- Liu, Yongzhu,Qi, Xinxin,Wu, Xiao-Feng
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p. 13824 - 13832
(2021/10/12)
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- Simplified preparation of a graphene-co-shelled Ni/NiO@C nano-catalyst and its application in theN-dimethylation synthesis of amines under mild conditions
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The development of Earth-abundant, reusable and non-toxic heterogeneous catalysts to be applied in the pharmaceutical industry for bio-active relevant compound synthesis remains an important goal of general chemical research.N-methylated compounds, as one of the most essential bioactive compounds, have been widely used in the fine and bulk chemical industries for the production of high-value chemicals. Herein, an environmentally friendly and simplified method for the preparation of graphene encapsulated Ni/NiO nanoalloy catalysts (Ni/NiO@C) was developed for the first time, for the highly selective synthesis ofN-methylated compounds using various functional amines and aldehydes under easy to handle, and industrially applicable conditions. A large number of primary and secondary amines (more than 70 examples) could be converted to the correspondingN,N-dimethylamines with the participation of different functional aldehydes, with an average yield of over 95%. A gram-scale synthesis also demonstrated a similar yield when compared with the benchmark test. In addition, it was further proved that the catalyst could easily be recycled because of its intrinsic magnetism and reused up to 10 times without losing its activity and selectivity. Also, for the first time, the tandem synthesis ofN,N-dimethylamine products in a one-pot process, using only a single earth-abundant metal catalyst, whose activity and selectivity were more than 99% and 94%, respectively, for all tested substrates, was developed. Overall, the advantages of this newly developed method include operational simplicity, high stability, easy recyclability, cost-effectiveness of the catalyst, and good functional group compatibility for the synthesis ofN-methylation products as well as the industrially applicable tandem synthesis process.
- Liu, Jianguo,Ma, Longlong,Song, Yanpei,Zhang, Mingyue,Zhuang, Xiuzheng
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supporting information
p. 4604 - 4617
(2021/06/30)
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- Synthesis and Structure-Activity Relationships of 3-Arylisoquinolone Analogues as Highly Specific hCES2A Inhibitors
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Mammalian carboxylesterases (CES) are key enzymes that participate in the hydrolytic metabolism of various endogenous and exogenous substrates. Human carboxylesterase 2A (hCES2A), mainly distributed in the small intestine and colon, plays a significant ro
- Zhao, Yitian,Xiong, Yuan,Dong, Sanfeng,Guan, Xiaoqing,Song, Yunqing,Yang, Yanqing,Zou, Kun,Li, Zhao,Zhang, Yong,Fang, Shengquan,Li, Bo,Zhu, Weiliang,Chen, Kaixian,Jia, Qi,Ge, Guangbo
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p. 388 - 398
(2020/10/26)
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- Discovery of dihydrooxazolo[2,3-: A] isoquinoliniums as highly specific inhibitors of hCE2
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Human carboxylesterase 2 (hCE2) is one of the most abundant esterases distributed in human small intestine and colon, which participates in the hydrolysis of a variety of ester-bearing drugs and thereby affects the efficacy of these drugs. Herein, a new c
- Ding, Lixia,Wang, Lu,Zou, Kun,Li, Bo,Song, Yunqing,Zhang, Qihua,Zhao, Yitian,Xu, Zhijian,Ge, Guangbo,Zhao, Bo,Zhu, Weiliang
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p. 35904 - 35912
(2019/11/16)
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- Synthesis of protoberberines using a silyl-directed Pictet-Spengler cyclization
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Five naturally-occurring protoberberines have been synthesized in enantioenriched form by alkylation by two different 2-trimethylsilylbenzyl chlorides of four tetrahydroisoquinolines, derivatized with Meyers' formamidine valinol methyl ether chiral auxiliary. Silyl-directed Pictet-Spengler cyclization of the ensuing 3,4-dimethoxy-2-trimethylsilylbenzyl tetrahydroisoquinolines leads to four of the target protoberberines in excellent yield and complete regioselectivity. In the fifth case, the 3,4-methylenedioxy analog gives a mixture of protoberberine and a product of ring closure at C6 of the benzyl moiety in a 3:4 ratio.
- Cutter, Paul S,Miller, R.Bryan,Schore, Neil E
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p. 1471 - 1478
(2007/10/03)
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- Total synthesis of (-)-tetrahydropalmatine via chiral formamidine carbanions: Unexpected behavior with certain ortho-substituted electrophiles
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A method has been developed by alkylation of chiral lithioformamidines to construct protoberberine alkaloids with a C(9) and C(10) D-ring substitution pattern. This ring pattern was established using an ortho-substituted hydroxymethylbenzene electrophile protected as a silyl ether to ultimately provide (-)-tetrahydropalmatine in 88% ee. Additionally, we have discovered limitations with ortho-substituted electrophiles in the asymmetric formamidine alkylation. These electrophiles have the potential to disrupt the lithium formamidine chelate and cause the selectivity in the alkylation to be uncharacteristically low. The total synthesis of (±)-canadine and (-)-tetrahydropalmatine along with the limitations to the formamidine alkylation technology are delineated herein.
- Matulenko, Mark A.,Meyers
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p. 573 - 580
(2007/10/03)
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- Thermodynamics, kinetics, and mechanism of exchange of cyclopalladated ligands
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The exchange between cyclopalladated complexes and free ligands has been studied in acetic acid. An equilibrium study of the system based on N,N-dimethylbenzylamine derivatives [PdX(YZC6H2CH2NMe2)]2 + 2C6D5CD2NMe2 ? [PdX-(C6D4CD2NMe2)]2 + 2YZC6H2DCH2NMe2 (K1) has revealed that Pd(II) binds preferably with the electron-poorest ligand at equilibrium; K1 is 114, 0.59, 0.125, 0.008, and 0.0034 for 4-Y (5-Z) = MeO (MeO), H (Me), H (H), H (Cl), and H (NO2), respectively, at 55°C in D3CCOOD/CDCl3, X = MeCO2-. A procedure for regioselective ortho palladation of bifunctional derivatives such as 1-(3,4-dimethoxyphenyl)-2-methyl-3-(4-nitrophenyl)-2-azapropane (7) is put forward. In aprotic chloroform, Pd(II) acetate metalates the electron-rich ring of 7 to yield 8a, but the electron-poor ring is ortho palladated in acetic acid to yield 9a. A dissociative exchange mechanism is proposed on the basis of a kinetic study of reactions between [PdX-(YZC6H2CH2NMe2)]2 and 2-phenylpyridine or azobenzene to afford the corresponding cyclopalladated complexes. Preequilibrium measurements have indicated that in the former case the reactive species are monomers formed via acetate-bridge cleavage by 2-phenylpyridine but in the latter case the complexes react as dimers. Despite this, all of the reactions are first order in complex and zero order in entering ligand. The rate constants of the 2-phenylpyridine case at 75°C are (104k) 12.6, 3.9, 2.35, 2.6, 0.44, and 0.0225 s-1 for 4-Y (5-Z) = MeO (MeO), H (Me), H (H), H (MeO), H (Cl), and H (NO2), respectively. On the basis of substituent and solvent kinetics isotope effects, values of activation parameters, and data obtained previously, it has been suggested that cleavage of the Pd-N bond of the leaving ligand occurs first, followed by acidolysis of the Pd-C bond. Both steps can contribute to the overall rate. The two are followed by the rapid activation of the C-H bond of the incoming ligand. Reasons for the pseudonucleophilic behavior of Pd(II) toward C-H bonds of benzylamines in acetic acid have been evaluated on the basis of the proposed mechanism.
- Ryabov, Alexander D.
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p. 1252 - 1260
(2008/10/08)
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