- Selective formation of a two-dimensional coordination polymer based on a tridentate phospholane ligand and gold(i)
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The tridentate phosphine ligand 1,3,5-tris[(E)-(4-phospholano-2,6-diethyl)styryl]benzene (1) reacts with [AuCl(tht)] (tht = tetrahydrothiophene) independent of the stoichiometry employed with selective formation of a two-dimensional coordination polymer (
- Hoy, Reinhard,L?nnecke, Peter,Hey-Hawkins, Evamarie
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- Selective formation of a supramolecular coordination complex in the nanometre scale with a ferrocene-based phospholane ligand
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A straightforward synthesis of the tetradentate phospholane ligand 1 is reported. The 2?:?1 [M?:?L] reaction of 1 with [AuCl(tht)] (tht = tetrahydrothiophene) resulted in the 4?:?2 [M?:?L] supramolecular coordination complex 2 where two ligands 1 are brid
- Grell, Toni,Hey-Hawkins, Evamarie,Hoy, Reinhard,L?nnecke, Peter
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- Chiral nickel(II) and palladium(II) catalysts bearing strong electron-withdrawing fluorine groups: Synthesis, characterization and their application in catalytic polymerization for ethylene and styrene
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A series of new chiral and achiral nickel(II) and palladium(II) complexes, {bis[N,N-(2,6-diethyl-4-naphthylphenyl)imino]-1,2-dimethylethane}dibromonickel 3a, {bis[N,N-(4-fluoro-2-methyl-6-sec-phenethylphenyl)imino]-1,2-dimethylethane} dibromonickel rac-(RS)-3b, {bis[N,N-(4-fluoro-6-sec-phenethylphenyl)imino]-1,2- dimethylethane}dibromonickel rac-(RR/SS)-3c and {bis[N,N-(4-fluoro-6-sec- phenethylphenyl)imino]-1,2-dimethylethane}dichloropalladium rac-(RR/SS)-3d were successfully synthesized and characterized. The molecular structures of representative ligand rac-(RS)-2b, nickel complex 3a, rac-(RR/SS)-3c and palladium complex rac-(RR/SS)-3d were determined by X-ray crystallography. The structures of complexes 3a and rac-(RR/SS)-3c have pseudo-tetrahedral geometry about the nickel center, showing C2 molecular symmetry. However, the structure of palladium complex rac-(RR/SS)-3d has pseudo-square planar geometry about the palladium center, showing C2 molecular symmetry. Complex 3e {bis[N,N-(2,6-dimethylphenyl)imino]-1,2-dimethylethane}dibromonickel was also synthesized for comparison. Nickel complex rac-(RS)-3b bearing strong electron-withdrawing fluorine group in the para-aryl position and a chiral sec-phenethyl group in the ortho-aryl position of the ligand (one methyl group in the ortho-aryl position) displays the highest catalytic activity for ethylene and styrene polymerization, and produced highly branched polyethylene and syndiotactic-rich polystyrene. However, palladium complex rac-(RR/SS)-3d shows low catalytic activity for ethylene and styrene polymerization due to the poor leaving group, Cl, attached to palladium and the unfavorable molecular structure. Copyright
- Yuan, Jianchao,Zhao, Jie,Song, Fengying,Xu, Weibing,Mu, Yanqiong,Chen, Jingjing,Zhang, Zhenghua
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- Synthesis of N-heterocyclic carbene ligands for site-selective C-H alkylation by cooperative nickel/aluminum catalysis
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We report synthesis of N-heterocyclic carbenes (NHCs), N,N'-bis{2,6-bis(3,5-dialkylphenyl)methy-4-methoxyphenyl}imidazol-2-ylidenes {alkyl = ethyl (L2) or n-propyl (L3)} and their applications to nickel-catalyzed C-H alkylation reactions of arenes. They s
- Okumura, Shogo,Ebara, Tomohiro,Semba, Kazuhiko,Nakao, Yoshiaki
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p. 1128 - 1144
(2019/08/01)
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- Fast and efficient bromination of aromatic compounds with ammonium bromide and Oxone
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A highly efficient, rapid and regioselective protocol was developed for the ring bromination of aromatic compounds under mild conditions with ammonium bromide as a source of bromine source and Oxone (potassium peroxysulfate) as an oxidant. No metal catalyst or acidic additive is required. A variety of aromatic compounds, including methoxy, hydroxy, amino, and alkyl arenes, reacted smoothly to give the corresponding monobrominated products in good to excellent yields in very short reaction times. Moreover, dibromination of deactivated anilines to give the corresponding dibromides proceeded in high yields. Interestingly, 1-(2-naphthyl)ethanone provided a ring-brominated product. Georg Thieme Verlag Stuttgart . New York.
- Naresh, Mameda,Arun Kumar, Macharla,Mahender Reddy, Marri,Swamy, Peraka,Nanubolu, Jagadeesh Babu,Narender, Nama
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p. 1497 - 1504
(2013/06/27)
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- PHOSPHORESCENT EMITTERS AND HOST MATERIALS WITH IMPROVED STABILITY
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Devices containing a particular combination of organic compounds are provided. In particular, the devices contain twisted aryl compounds having extended conjugation (i.e., the twisted aryl is substituted with an additional aryl group) in combination with dibenzothiophene or dibenzofuran containing host materials. The organic light emitting devices may provide improved stability color, lifetime and manufacturing. Compounds containing a twisted aryl having extended conjugation are also provided.
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- Transformation of mutagenic aromatic amines into non-mutagenic species by alkyl substituents: Part I. Alkylation ortho to the amino function
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Alkyl-substituted derivatives of 2-aminonaphthalene (2-AN) 1, 2-aminofluorene (2-AF) 6 and 4-aminobiphenyl (4-ABP) 11 were synthesized and the mutagenic activity of these compounds determined in Salmonella typhimurium strains TA98 and TA100 with and without S9 mix. In the case of the ortho-substituted 4-aminobiphenyls 12-15 (3-alkyl = ethyl, iso-propyl, n-butyl, tert-butyl) the substituent with the strongest steric demand (3-tert-butyl) shows the strongest influence on the decrease of mutagenicity if compared with the parent compound. In the series of the bis-ortho-disubstituted compounds 16-18 (3,5-dimethyl-, 3,5-diethyl- and 3,5-diisopropyl-4-aminobiphenyl) generation of non-mutagenic species occurs already with the introduction of two ethyl groups. For the 4-aminobiphenyl derivatives 12-15 and 16-18, as well as for the 1-alkylated 2-aminofluorenes 7-10 and the 1-alkylated 2-aminonaphthalenes 2-5 a smaller mutagenicity was observed if compared with predicted mutagenicities as calculated by the QSAR equations of Debnath et al. (Environ. Mol. Mutagen. 19 (1992) 37). The largest differences resulted in the cases of the tert-butyl substituted compounds. Only with smaller alkyl groups like ethyl the QSAR predictions and the experimentally determined mutagenicities come close to each other. Thus, these results show that appropriate alkyl substitution reduces (eliminates) mutagenicity, secondly, it is necessary to introduce steric parameters to predict the mutagenicity of such compounds correctly.
- Glende, Carsten,Schmitt, Heimo,Erdinger, Lothar,Engelhardt, Guenter,Boche, Gernot
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- Endothelin antagonists
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A compound of the formula (I): or a pharmaceutically acceptable salt thereof is disclosed, as well as processes for and intermediates in the preparation thereof, and a method of antagonizing endothelin.
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- Pyrrolidine-3-carboxylic acids as endothelin antagonists. 4. Side chain conformational restriction leads to ET(B) selectivity
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When the dialkylacetamide side chain of the ETA-selective antagonist ABT-627 is replaced with a 2,6-dialkylacetanilide, the resultant analogues show a complete reversal of receptor selectivity, preferring ETB over ETA. By optimizing the aniline substitution pattern, as well as the alkoxy group on the 2-aryl substituent, it is possible to prepare antagonists with subnanomolar affinity for ETB and with selectivities in excess of 4000-fold. A number of these compounds also show promising pharmacokinetic profiles; a useful balance of properties is found in A-192621 (38). Pharmacology studies with A-192621 serve to reveal the role of the ETB receptor in modulating blood pressure; the observed hypertensive response to persistent ETB blockade is consistent with previous postulates and indicates that ETB-selective antagonists may not be suitable as agents for long-term systemic therapy.
- Von Geldern, Thomas W.,Tasker, Andrew S.,Sorensen, Bryan K.,Winn, Martin,Szczepankiewicz, Bruce G.,Dixon, Douglas B.,Chiou, William J.,Wang, Liming,Wessale, Jerry L.,Adler, Andy,Marsh, Kennan C.,Nguyen, Bach,Opgenorth, Terry J.
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p. 3668 - 3678
(2007/10/03)
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- Revisitation of Formaldehyde Aniline Condensation. VIII. - Monomeric N-Methylene Anilines
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A convenient, high yield "dry" method of synthesis of monomeric N-methyleneanilines (6a-i) and the characterization of the products by m.s., 1H- and 13C-n.m.r. and i.r. are reported, improving previous procedures and describing new compounds.It appeared that the existence of monomeric N-methyleneanilines is stricly related to the presence of enough steric hindrance to oligomerization by substituents in ortho positions.Moreover, some addition products of formaldehyde to an amine and its corresponding imines are tentatively identified on the basis of the observed mass spectrum of the whole reaction mixture.The reaction products of formaldehyde with 2,6-dimethylaniline (1a) provided an example of a mobile equilibrium between monomeric and trimeric imine.
- Giumanini, Angelo G.,Verardo, Giancarlo,Polana, Marco
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p. 161 - 174
(2007/10/02)
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- PROTECTION OF A 2,6-DIALKYLANILINE: SYNTHESIS OF 4-DIMETHYLMETHOXYSILYL-2,6-DIETHYLANILINE
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The synthesis of 4-dimethylmethoxysilyl-2,6-diethylaniline (1) from 2,6-diethylaniline (2) is described.An intermediate in the process, disilazane 5, appears to be the first 2,6-dialkylaniline to be protected with 1,1,5,5-tetramethyl-1,4-dichlorodisilethy
- Weisenfeld, R. B.,Miller, M. D.
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p. 809 - 818
(2007/10/02)
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