- Internal conversion in 4-substituted 1-naphthylamines. Influence of the electron donor/acceptor substituent character
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The thermally activated internal conversion (IC) taking place in 4- substituted 1-(dimethylamino)naphthalenes (14DMX) and 1-aminonaphthalenes (14ANX) with X = CN, Cl, H, CH3 and OCH3 was investigated in three solvents spanning the polarity scale, hexane, diethyl ether and acetonitrile. In both series 14DMX and 14ANX, the efficiency of the IC reaction decreases substantially when X changes from CN to OCH3, the order in which the electron donor character of the 4-substituent increases. Considerably larger IC reaction rate constants are obtained for the first group of compounds. This difference is connected with the ground state structure of the amino group, which is more strongly twisted for 14DMX (ca. 60°) than for 14ANX (ca. 20°), whereas both sets of 1-naphthylamines are planarised in the S1 excited state. The IC process slows down with increasing solvent polarity for each of the 14DMX and 14ANX molecules. The substituent X and the solvent polarity mainly affect the IC activation energy E(IC). With 14DMX in hexane, E(IC) increases from 10 kJ mol-1 for X = CN to 34 kJ mol-1 for X = OCH3, whereas with, e.g., 14DMCL a solvent polarity dependent increase of E(IC) from 16 kJ mol-1 in hexane to 28 kJ mol-1 in acetonitrile is observed. The height of the barrier E(IC) is governed by the energy gap ΔE(S1,S2) between the two lowest excited singlet states. The influence of δE(S1,S2) on E(IC) is attributed to vibronic coupling caused by the proximity of the S1 and S2 states, which flattens the S1 potential energy surface and thereby lowers the IC barrier when ΔE(S1,S2) becomes smaller. It is assumed that the IC reaction of the 1-naphthylamines passes through a conical intersection, which exists as a consequence of the relative displacement of the S1 and S0 surfaces caused by the different amino twist angles in the two states.
- Suzuki, Kengo,Demeter, Attila,Kuehnle, Wolfgang,Tauer, Erich,Zachariasse, Klaas A.,Tobita, Seiji,Shizuka, Haruo
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Read Online
- Cobalt-Catalyzed Direct Carbonylative Synthesis of Free (NH)-Benzo[ cd]indol-2(1 H)-ones from Naphthylamides
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A cobalt-catalyzed C-H carbonylation of naphthylamides for the synthesis of benzo[cd]indol-2(1H)-one scaffolds has been developed. The reaction employs a traceless directing group and uses benzene-1,3,5-triyl triormate as the CO source, affording various free (NH)-benzo[cd]indol-2(1H)-ones in moderate to high yields (up to 88%). Using this protocol, the total synthesis of BET bromodomain inhibitors A and B was accomplished as well.
- Ying, Jun,Fu, Lu-Yang,Zhong, Guoqiang,Wu, Xiao-Feng
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p. 5694 - 5698
(2019/07/08)
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- A Facile Synthesis of Benzo[h]quinolines via Silica-TsOH-P2O5 Promoted Condensation of 1-Naphthylamines with 1,3-Diketones under Solvent Free Conditions
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A facile synthesis of benzo[h]quinolines has been developed via improved Combes reaction. A combination of silica gel, p-toluenesulfonic acid and phosphorus pentoxide was utilized to promote the condensation of 1-naphthylamines with 1,3-diketones under solvent free conditions. In this case, silica gel was used as reaction media, p-toluenesulfonic acid and phosphorus pentoxide were acted as catalyst and dehydrating agent, respectively.
- Zhu, Chuanlei,Guo, Ruiqiang,Sheng, Zhe,Li, Yanzhe,Chu, Changhu
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supporting information
p. 1595 - 1600
(2017/10/06)
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- Co(II)-Catalyzed Regioselective Cross-Dehydrogenative Coupling of Aryl C-H Bonds with Carboxylic Acids
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A cobalt(II)-catalyzed regioselective aryl C-H bond oxygenation between arenes and aryl or aliphatic carboxylic acids under bidendate-chelation assistance is developed. This method provides an efficient approach to acyoxy-substituted arenes with a broad range of functional group tolerance. Furthermore, this reaction system could be further applied to the preparation of polyfunctional naphthylenes.
- Lan, Jianyong,Xie, Haisheng,Lu, Xiaoxia,Deng, Yuanfu,Jiang, Huanfeng,Zeng, Wei
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p. 4279 - 4282
(2017/08/23)
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- Ligand free open air copper(II) mediated aryl formamidation and amination of aryl halides
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A simple synthetic procedure for direct formamidation and amination of aryl halides mediated by copper(II) salts was developed in open air, without an external ligand in formamide with potassium carbonate as a base. This approach is particularly efficient when electron active aryl halides are used as substrates. In these cases almost quantitative formamidation was observed.
- Komati, Rajesh,Jursic, Branko S.
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p. 1523 - 1527
(2014/03/21)
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- Pd-catalyzed Semmler-Wolff reactions for the conversion of substituted cyclohexenone oximes to primary anilines
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Homogeneous Pd catalysts have been identified for the conversion of cyclohexenone and tetralone O-pivaloyl oximes to the corresponding primary anilines and 1-aminonaphthalenes. This method is inspired by the Semmler-Wolff reaction, a classic method that exhibits limited synthetic utility owing to its forcing conditions, narrow scope, and low product yields. The oxime N-O bond undergoes oxidative addition to Pd0(PCy3)2, and the product of this step has been characterized by X-ray crystallography and shown to undergo dehydrogenation to afford the aniline product.
- Hong, Wan Pyo,Iosub, Andrei V.,Stahl, Shannon S.
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supporting information
p. 13664 - 13667
(2013/10/01)
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- Adjusting conformational switching behavior of helical polycarbodiimides through substituent induced polarity effects
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Recent discoveries on the improved versatility of helical polycarbodiimides capable of undergoing low energy reversible conformational changes from realignment of their restricted polyarene pendant groups has led to seven new polycarbodiimides that each present unique information in regards to how the electronics and connectivity of the arene π-system play a crucial role in the behavior of these polymers. In addition to their individual anomalous behavior, this series of functional polymers unlock new answers toward the global understanding of the governing forces behind this complex switching process. Through the incorporation of functional groups covalently attached to the naphthalene pendant, dramatic changes and new application of these systems are realized. Variable temperature polarimetry is used to observe the reversible conformational changes of these chiral polymers.
- Kennemur, Justin G.,Kilgore, Chris A.,Novak, Bruce M.
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experimental part
p. 719 - 728
(2012/01/17)
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- S-TRIAZOLYL α-MERCAPTOACETANILDES AS INHIBITORS OF HIV REVERSE TRANSCRIPTASE
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A series of S-triazolyl α-mercaptoacetanilides having general structure (1) are provided, where Q is CO2H, CONR2, SO3H, or SO2NR2. The compounds inhibit several variants of the reverse transcriptase of HIV, and are useful in the treatment of HIV infections.
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Page/Page column 42
(2010/10/20)
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- Substituent effects on homolytic versus heterolytic photocleavage of (1-naphthylmethyl)trimethylammonium chlorides
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Singlet escited state rate constants have been measured for both the heterolytic and homolytic photocleavage of 3- and 4-methoxy and 3- and 4-cyano (1-naphthylmethyl)trimethylammonium chlorides, 6-10.The results are interpreted in terms of the meta effect or changes in charge distribution upon excitation and the competition between bond cleavage, electron transfer, and hydrogen atom transfer in the contact pairs resulting from the two types of cleavage.
- Foster, B.,Gaillard, B.,Mathur, N.,Pincock, A. L.,Pincock, J. A.,Sehmbey, C.
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p. 1599 - 1607
(2007/10/02)
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