- Room temperature C(sp2)-H oxidative chlorination: Via photoredox catalysis
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Photoredox catalysis has been developed to achieve oxidative C-H chlorination of aromatic compounds using NaCl as the chlorine source and Na2S2O8 as the oxidant. The reactions occur at room temperature and exhibit exclusive selectivity for C(sp2)-H bonds over C(sp3)-H bonds. The method has been used for the chlorination of a diverse set of substrates, including the expedited synthesis of key intermediates to bioactive compounds and a drug.
- Zhang, Lei,Hu, Xile
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p. 7009 - 7013
(2017/10/05)
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- 4′-Alkoxyl substitution enhancing the anti-mitotic effect of 5-(3′,4′,5′-substituted)anilino-4-hydroxy-8-nitroquinazolines as a novel class of anti-microtubule agents
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Mitosis inhibitors are powerful anticancer drugs. Based on a novel anti-microtubule agent of 5-(4′-methoxy)anilino-4-hydroxy-8-nitroquinazoline, a series of 5-(3′,4′,5′-substituted)anilino-4-hydroxy-8- nitroquinazolines were designed and synthesized to investigate the effect of the substitution on the inhibitory activity against mitotic progression of tumor cells. The large alkoxyl substitution on the 4′-position of 5-anilino ring is beneficial for the potency. The 5-(3′,4′,5′-trimethoxy)anilino-8-nitroquinazoline (1h) displays an overwhelming activity in arresting the cells at the G2/M phase, providing a promising new template for further development of potent microtubule-targeted anti-mitotic drugs.
- Jin, Yi,Zhou, Zu-Yu,Tian, Wei,Yu, Qiang,Long, Ya-Qiu
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p. 5864 - 5869
(2007/10/03)
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- Selective nitration of aromatic compounds with bismuth subnitrate and thionyl chloride
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Bismuth subnitrate/thionyl chloride have been found to be an efficient combination of reagents for nitration of a wide range of aromatic compounds in dichloromethane. Phenols, in particular, were easily mononitrated and dinitrated with the reagents by controlling the stoichiometry.
- Muathen, Hussni A.
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p. 593 - 598
(2007/10/03)
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- Oxidative chlorination of various lodoarenes to (dichloroiodo)arenes with chromium(vi) oxide as the oxidant j
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Chromium(vi) oxide dissolved in a mixture of acetic acid with concentrated hydrochloric acid converts, at or near room temperature, iodoarenes to (dichloroiodo)arenes, in a very simple and efficient procedure.
- Kazmierczak, Pawet,Skulski, Lech,Obeid, Nicolas
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- Chemoselective O-methylation of phenols under non-aqueous condition
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Chemoselective O-methylation of substituted phenols takes place in dry. tetrahydrofuran (THF) in the presence of LiOH.H2O and dimethylsulfate (DMS). Quantitative methyl transfer from DMS preserves the atom economy.
- Basak, Anindita,Nayak, Mrinal K.,Chakraborti, Asit K.
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p. 4883 - 4886
(2007/10/03)
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- Polyaza Heterocycles. Part 2. Nucleophilic Substitution of Halogens in Halogenoquinoxalinocinnolines
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10-Chloroquinoxalinocinnoline readily undergoes methoxydechlorination when treated with sodium methoxide.The 1-, 2-, 3-, 4- and 9-chloro isomers are unreactive towards this reagent, but the 9,10-dichloro derivative undergoes substitution of both chlorines (the 10-position being much the more reactive).The 9- and 10-bromo analogues are both unreactive towards sodium methoxide, but the 9- and 10-fluoro analogues are both highly reactive, to the extent that it has not been possible even to isolate the 10-fluoro compound.Routes to 9- and 10-piperidinoquinoxalinocinnolines are described.
- Ahmad, Arshad,Dunbar, Linda J.,Green, Iain G.,Harvey, Ian W.,Shepherd, Thomas,et al.
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p. 2751 - 2758
(2007/10/02)
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- Multinuclear Magnetic Resonance Spectroscopic and Semiempirical Molecular Orbital (AM1) Studies of Substituted Anisoles
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13C, 15N, and 17O NMR spectra have been recorded for 4-nitroanisole (1), its 2-methyl-, 2-chloro-, 2-bromo-, 2-iodo-, 2,6-diamethyl-, 2,6-dichloro, 2,6-dibromo-, and 2,6-diiodo-derivatives 2-9, also nitrobenzene (1a), its 3-methyl-, 3-chloro-, 3-bromo-, and 3-iodo-derivatives 2a-5a and 3,5-dichloro- and 3,5-dibromo-derivatives 7a and 8a.Analysis of the chemical shifts of carbon bearing nitro group and nitro oxygens in these compounds suggests that presence of one substituent ortho- to the methoxyl group enhances its resonance interaction with the benzene ring whereas presence of two ortho-substituents inhibits this resonance.However, in no case the resonance is completely inhibited.The extent of enhancement or inhibition is almost independent of the nature of the ortho-substituent.This conclusion has also been arrived by analyzing the reported chemical shifts of the para-carbons in anisoles 1b-9b and the corresponding carbons in benzene derivatives 1c-9c.Though evidence could not be obtained for steric enhancement of resonance using methoxyl oxygen chemical shifts, analysis of these chemical shifts in di-ortho-substituted anisoles 6-9 and 6a furnishes evidence for steric inhibition of resonance.However, 15N chemical shifts are of no use in studying these phenomena.Semiempirical molecular orbital calculations using AM1 Hamiltonian suggest that the methoxyl group is coplanar with the benzene ring in anisole, 4-nitroanisole and 2-substituted-4-nitroanisoles but is perpendicular to the benzene ring in 2,6-disubstituted-4-nitroanisoles.Moreover, in 2-substituted-4-nitroanisoles the O-methyl group is anti to the 2-substituent.
- Pandiarajan, Karuppiah,Kabilan, Senthamaraikannan,Sankar, Punnaivanam,Kolehmainen,Erkki,Nevalainen, Tapio,Kauppinen, Reijo
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p. 2639 - 2646
(2007/10/02)
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- FORMATION OF METHOXY-SUBSTITUTED AZOXYBENZENES IN THE REDUCTION OF NITROARENES IN BASIC METHANOL-TOLUENE SOLUTIONS
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The reduction of nitroarenes in boiling methanol-toluene containing KOH affords high yields of the corresponding azoxy derivative and small amounts of other azoxy compounds containing one or more OCH3 groups linked to the aromatic rings.It has been proved that the reaction does not occur via formation of methoxy-nitroarenes and their further reduction.The reaction is proposed to involve: a) formation of a Meisenheimer complex by attack of the methoxide ion on the nitroarene; b) abstraction of a proton from the Meisenheimer complex by a methoxide ion to form a dianion; c) protonation of the dianion with concurrent elimination of OH to form the nitroso-methoxy arene which is finally reduced to the methoxy-azoxy derivative.It is proposed that the dianion is the electron-donating species to start the reduction of nitro- and nitrosoarenes.
- Prato, Maurizio,Quintily, Ugo,Scorrano, Gianfranco
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p. 421 - 426
(2007/10/02)
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- STUDIES OF METHOXYLATION OF 3,4-DICHLORONITROBENZENE.
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The authors report the results of studies of methoxylation of 3,4-dichloronitrobenzene (3,4-DCNB), carried out in order to find the optimal conditions for production of highly pure 3-chloromethoxynitrobenzene. Experiments indicate that the optimal conditions of methoxylation of 3,4-dichloronitrobenzene in alkaline aqueous alcohol solutions are: 3,4-DCNB:methanol:NaOH molar ratio 1:15:1. 1, temperature 72 degree , time 5 h, alkali concentration 15%. The reaction of 3,4-DCNB methoxylation under the above optimal conditions is described by a second-order equation.
- Shamsutdinov,Poluektova,Kalistratova,Starkov
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p. 794 - 796
(2007/10/02)
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- The Kinetics of the Reactions of Picryl Chloride with Some Substituted Anilines. Part 6. 4-Substituted and 3,4-Disubstituted Anilines
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Arrhenius parameters have been measured for the reactions of picryl chloride with the following substituted anilines in acetonitrile: 4-X- (X = F, Cl, Br, I, Me, or OMe); 3,4-X2- (X = Cl, Br, Me, or OMe); 4-X-3-nitro- (X = F, Cl, or Me); 3-X-4-methoxy- (X = F, Cl, Br, or I); 3-fluoro-4-nitro-; and 3,4,5-trimethoxy-aniline.In the 3,4-disubstituted series the effect of two methyl groups on the free energy of activation is strictly additive, but for the rest the measured rate constants are greater than those calculated on the assumption of additivity.The results are rationalized in terms of the positions of the transition state on the reaction co-ordinate.
- Emokpae, Thomas A.,Eguavoen, Osa,Khalil-Ur-Rahman,Hirst, Jack
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p. 832 - 834
(2007/10/02)
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