13171-59-0Relevant academic research and scientific papers
IMPROVED STABILITY OLED MATERIALS AND DEVICES
-
Page/Page column 89, (2008/12/05)
Organic light emitting materials and devices comprising phosphorescent metal complexes comprising ligands comprising aryl or heteroaryl groups substituted at both ortho positions are described. An organic light emitting device, comprising: an anode; a hole transport layer; an organic emissive layer comprising an emissive layer host and an emissive dopant; an electron impeding layer; an electron transport layer; and a cathode disposed, in that order, over a substrate.
STABILITY OLED MATERIALS AND DEVICES WITH IMPROVED STABILITY
-
Page/Page column 82, (2010/11/24)
Organic light emitting materials and devices comprising phosphorescent metal complexes comprising ligands comprising aryl or heteroaryl groups substituted at both ortho positions are described. An organic light emitting device, comprising: an anode; a hole transport layer; an organic emissive layer comprising an emissive layer host and an emissive dopant; an electron impeding layer; an electron transport layer; and a cathode disposed, in that order, over a substrate.
Endothelin antagonists: Substituted mesitylcarboxamides with high potency and selectivity for ET(A) receptors
Wu, Chengde,Decker, E. Radford,Blok, Natalie,Bui, Huong,Chen, Qi,Raju,Bourgoyne, Andree R.,Knowles, Vippra,Biediger, Ronald J.,Market, Robert V.,Lin, Shuqun,Dupré, Brian,Kogan, Timothy P.,Holland, George W.,Brock, Tommy A.,Dixon, Richard A. F.
, p. 4485 - 4499 (2007/10/03)
We have previously disclosed the discovery of 2,4-disubstituted anilinothiophenesulfonamides with potent ET(A)-selective endothelin receptor antagonism and the subsequent identification of sitaxsentan (TBC11251, 1) as a clinical development compound (Wu et al. J. Med. Chem. 1997, 40, 1682 and 1690). The orally active 1 has demonstrated efficacy in a phase II clinical trial of congestive heart failure (Givertz et al. Circulation 1998, 98, Abstr. 3044) and was active in rat models of myocardial infarction (Podesser et al. Circulation 1998, 98, Abstr. 2896) and acute hypoxia-induced pulmonary hypertension (Chen et al. FASEB J. 1996, 10 (3), A104). We now report that an additional substituent at the 6-position of the anilino ring further increases the potency of this series of compounds. It was also found that a wide range of functionalities at the 3-position of the 2,4,6-trisubstituted ring increased ETA selectivity by ~10-fold while maintaining in vitro potency, therefore rendering the compounds amenable to fine-tuning of pharmacological and toxicological profiles with enhanced selectivity. The optimal compound in this series was found to be TBC2576 (7u), which has ~10- fold higher ETA binding affinity than 1, high ET(A)/ET(B) selectivity, and a serum half-life of 7.3 h in rats, as well as in vivo activity.
Photochemical nitration by tetranitromethane. Part XXXIV. The photochemical reactions of pentamethylbenzene and hexamethylbenzene with tetranitromethane. The formation and rearrangement of labile adducts from pentamethylbenzene
Eberson, Lennart,Hartshorn, Michael P.,Timmerman-Vaughan, David J.
, p. 1121 - 1136 (2007/10/03)
The photolysis of the charge transfer (CT) complex of tetranitromethane and Pentamethylbenzene (13) in dichloromethane at - 50 or - 78°C gives the labile epimeric 1,2,3,4,6-pentamethyl-3-nitro-6-trinitromethylcyclohexa-1,4-dienes 18 and 19. Adduct 18 rearranges rapidly in [2H2]dichloromethane at 22°C (half-life 9 min) to give 2,3,4,5-tetrarnethyl-1-(2′,2′,2′-trinitroethyl)benzene (21), 2,3,4,5-tetramethylphenylnitromethane (26), 2,3,4,5-tetramethylbenzyl nitrate (32) and 2,3,4,5-tetramethylbenzyl nitrite (36). The photolysis of the tetranitromethane-13 CT complex in dichloromethane at 20°C gives compounds 21, 26, 32 and 36, in addition to their 2,3,4,6-tetramethyl analogues 20, 25, 31 and 35, the latter set of products probably arising from the rearrangement of the highly labile epimeric 1,2,3,5,6-pentamethyl-3-nitro-6-trinitromethylcyclohexa-1,4-dienes 54. The photolysis of the tetranitromethane-13 CT complex in acetonitrile gives mainly the phenylnitromethane 26, while similar reaction in 1,1,1,3,3,3-hexafluoropropan-2-ol yields pentamethylnitrobenzene 24, the latter by a nitrosation/oxidation sequence. Reaction of 13 with nitrogen dioxide in dichloromethane gives mainly compounds 26 and 30. No adducts were detected in the photolysis of the CT complex of hexamethylbenzene 14 in dichloromethane at accessible reaction temperatures (≥ -20°C), but products of side-chain modification 37-46 were formed. In acetonitrile similar reaction gave in addition to the above products 37-46 the N-nitrosoacetamide 47 and its precursor 49. Compounds 47 and 49 are also formed, along with the major products pentamethylbenzyl nitrate 39 and the mono- and di-nitromethyl compounds 40 and 43, on reaction of 14 with nitrogen dioxide in acetonitrile. EPR spectroscopic examination of the photolysis of acidic (trifluoroacetic acid, 0.4 mol dm-3) solutions of tetranitromethane and 13 or 14 demonstrated the formation of the corresponding radical cation or a transformation product thereof, i.e. the 1,2,3,4,5,6,7,8-octamethylanthracene radical cation from 13 or 14·+ from 14. Acta Chemica Scandinavica 1996.
Oxidation of Aromatic Compounds. I. Oxidation of Methyl Derivatives of Nitrobenzene and Aniline in the System HSO3F-PbO2
Rudenko, A. P.,Korovina, N. S.,Aver'yanov, S. F.
, p. 1077 - 1083 (2007/10/03)
Low-temperature oxidation of methyl derivatives of nitrobenzene and aniline in the system HSO3F-PbO2 proceeds with intermediate formation of radical cations and results in replacement of hydrogen in one or two methyl groups or yields compounds of the diphenylmethane and biphenyl series.
Direct Nitrosation of Aromatic Hydrocarbons and Ethers with the Electrophilic Nitrosonium Cation
Bosch, Eric,Kochi, Jay K.
, p. 5573 - 5586 (2007/10/02)
Various polymethylbenzenes and anisoles are selectively nitrosated with the electrophilic nitrosonium salt NO(1+)BF4(1-) in good conversions and yields under mild conditions in which the conventional procedure (based on nitrile neutralization with strong acid) is ineffective.The reactivity patterns in acetonitrile deduced from the various time/conversions in Tables 2 and 3 indicate that aromatic nitrosation is distinctly different from those previously established for electrophilic aromatic nitration.The contrasting behavior of NO(1+) in aromatic nitrosation is ascribed to a rate-limiting deprotonation of the reversibly formed Wheland intermediate, which in the case of aromatic nitration with NO2(1+) occurs with no deuterium kinetic isotope effect.Aromatic nitroso derivatives (unlike the nitro counterpart) are excellent electron donors that are subject to a reversible one-electron oxidation at positive potentials significantly less than that of the parent polymethylbenzene or anisole.As a result, the series of nitrosobenzenes are also much better Broensted bases than the corresponding nitro derivatives, and this marked distinction, therefore, accounts for the large differentiation in the deprotonation rates of their respective conjugate acids (i.e.Wheland intermediates).
Positional Reactivity of Acylpolymethylbenzenes in Electrophilic Substitution
Matsuura, Kazunori,Kimura, Yasuo,Takahashi, Hisakazu,Morita, Toshio,Takahashi, Ichiro,et al.
, p. 757 - 765 (2007/10/02)
Friedel-Crafts acylation, bromination, deuteration, and nitration of acetylpentamethylbenzene (APMB), 1-acetyl-2,3,4,6-tetramethylbenzene (ATMB), and 1-benzoyl-2,3,4,6-tetramethylbenzene (BTMB) and the resulting product distribution were investigated.Friedel-Crafts acylation, bromination, and deuteration of APMB and Friedel-Crafts acylation of ATMB gave deacetylation-substitution products.On the other hand, bromination and deuteration of ATMB (or BTMB) and Friedel-Crafts acylation of BTMB gave 5-substituted products.In both cases, the positional reactivities were in accordance with the relative ?-complex stability.Conversely, except for Friedel-Crafts-type nitration, the positional reactivities in the nitration of these substrates were strikingly different from those of the above three reactions.Thus, side-chain functionalization at the 6-methyl group occurred in nitration with fuming nitric acid, depending on the solvents in use.The NMDO calculations and the reaction of APMB with single-electron transfer reagents such as tetranitromethane-hν or cerium(IV) ammonium nitrate suggest that the product distribution in nitration can be explained in terms of a single-electron transfer mechanism.
Thermal and Photochemical Nitration of Aromatic Hydrocarbons with Nitrogen Dioxide
Bosch, E.,Kochi, J. K.
, p. 3314 - 3325 (2007/10/02)
Aromatic hydrocarbons (ArH) are readily nitrated by nitrogen dioxide (NO2) in dichloromethane at room temperature and below (in the dark).The red colors, transiently observed, arise from the metastable precursor complex NO3(1-), which is formed in the prior disproportionation of nitrogen dioxide induced by the aromatic donor (eq 7).The deliberate irradiation of the diagnostic (red) charge-transfer absorption band (hνCT) of NO3(1-) at low temperatures results directly in aromatic nitration, even at -78 deg C, where the thermal nitration is too slow to complete.The mechanism of the photochemical (charge-transfer) nitration is established by time-resolved laser spectroscopy to proceed via the aromatic cation radical (ArH.+) formed spontaneously upon the charge-transfer excitation of NO3(1-) in Scheme 1.The related thermal activation of NO3(1-) derives from the adiabatic electron transfer that produces the same radical pair as the reactive intermediate in Scheme 3.The close relationship between the thermal/photochemical nitrations with nitrogen dioxide and those conventionally carried out with nitric acid (in the presence of nitrous acid) is delineated by Scheme 4.
Aromatic nitration with electrophilic N-nitropyridinium cations. Transitory charge-transfer complexes as key intermediates
Kim,Lee,Kochi
, p. 1756 - 1770 (2007/10/02)
Electrophilic aromatic nitration of various arenes (ArH) is shown to be critically dependent on labile charge-transfer complexes derived from N-nitropyridinium cations. The electrophiles XPyNO2+, with X = CN, CO2CH3, Cl, H, CH3, and OCH3, form a highly graded series of electron acceptors that produce divers [ArH,XPyNO2+] complexes, with charge-transfer excitation energies (hvCT) spanning a range of almost 50 kcal mol-1. The latter underlie an equally broad spectrum of aromatic substrate selectivities from the different nitrating agents (XPyNO2+), but they all yield an isomeric product distribution from toluene that is singularly insensitive to the X substituent. The strong correlation of the nitration rates with the HOMO-LUMO gap in the [ArH,XPyNO2+] complex is presented (Scheme III) in the context of a stepwise process in which the charge-transfer activation process is cleanly decoupled from the product-determining step-as earlier defined by Olah's requirement of several discrete intermediates. This charge-transfer formulation thus provides a readily visualized as well as a unifying mechanistic basis for the striking comparison of XPyNO2+ with other nitrating agents, including the coordinatively unsaturated nitronium cation (NO2+BF4-), despite their highly differentiated reactivities.
Ortho-Selective Side-Chain Nitration of Methyl-Substituted Alkenoylbenzenes and Its Application to Synthesis of 4-Nitro-1-tetralones
Keumi, Takashi,Inagaki, Toshihiko,Nakayama, Norihiro,Taniguchi, Masaaki,Morita, Toshio,Kitajima, Hidehiko
, p. 4034 - 4038 (2007/10/02)
Methyl-substituted alkenoylbenzenes 1a-m involving acryoyl, methacryloyl, β-(ethoxycarbonyl)acryloyl, crotonoyl, and cinnamoyl groups as alkenoyl functions reacted with fuming nitric acid in acetic anhydride to give 2-(nitromethyl)alkenoylbenzenes 2a-m in
