5919-26-6Relevant academic research and scientific papers
Click chemistry-facilitated structural diversification of nitrothiazoles, nitrofurans, and nitropyrroles enhances antimicrobial activity against giardia lamblia
Kim, Wan Jung,Korthals, Keith A.,Li, Suhua,Le, Christine,Kalisiak, Jaros?aw,Sharpless, K. Barry,Fokin, Valery V.,Miyamoto, Yukiko,Eckmann, Lars
, (2017)
Giardia lamblia is an important and ubiquitous cause of diarrheal disease. The primary agents in the treatment of giardiasis are nitroheterocyclic drugs, particularly the imidazoles metronidazole and tinidazole and the thiazole nitazoxanide. Although these drugs are generally effective, treatment failures occur in up to 20% of cases, and resistance has been demonstrated in vivo and in vitro. Prior work had suggested that side chain modifications of the imidazole core can lead to new effective 5-nitroimidazole drugs that can combat nitro drug resistance, but the full potential of nitroheterocycles other than imidazole to yield effective new antigiardial agents has not been explored. Here, we generated derivatives of two clinically utilized nitroheterocycles, nitrothiazole and nitrofuran, as well as a third heterocycle, nitropyrrole, which is related to nitroimidazole but has not been systematically investigated as an antimicrobial drug scaffold. Click chemistry was employed to synthesize 442 novel nitroheterocyclic compounds with extensive side chain modifications. Screening of this library against representative G. lamblia strains showed a wide spectrum of in vitro activities, with many of the compounds exhibiting superior activity relative to reference drugs and several showing 100-fold increase in potency and the ability to overcome existing forms of metronidazole resistance. The majority of new compounds displayed no cytotoxicity against human cells, and several compounds were orally active against murine giardiasis in vivo. These findings provide additional impetus for the systematic development of nitroheterocyclic compounds with nonimidazole cores as alternative and improved agents for the treatment of giardiasis and potentially other infectious agents.
Trichloroisocyanuric acid (TCCA) and carboxamide interactions in TCCA/NaNO2 triggered nitration of pyrrole and indole in aqueous aprotic media: A kinetic correlation of solvent properties with reactivity
Duguta, Govardhan,Muddam, Bhooshan,Kamatala, Chinna Rajanna,Utkoor, Umesh Kumar
, p. 164 - 186 (2020/10/02)
This study deals with the trichloroisocyanuric acid (TCCA) interactions with carboxamides like formamide (FMA), N,N′-dimethyl formamide (DMF), and N,N′-dimethyl acetamide (DMA) interactions during the nitration of heterocyclic compounds (HC) like pyrrole and indole in the presence of excess of [NaNO2] over the concentrations of all other reactants. All the reactions were performed in aqueous acetonitrile media containing carboxamide under acid-free conditions. Kinetics of the reactions revealed first order in [nitrating agent] and [HC] under otherwise similar conditions. To gain an insight into the reactive species and role of added carboxamide (FAA, DMF, DMA, etc.), the observed rates of the nitration reaction (log k) were analyzed as a function of (1/D), ([D ? 1]/[2D + 1]), mole fraction (nx), and volume (%) of carboxamide, 1/viscosity, density refractive index function), and Hildebrand solubility parameter plots. Linear regression analysis gave very good correlation coefficients (R2 values), which indicate the importance of several solvent properties in addition to the role of dielectric constant (D) of the reaction media. Multiple linear solvent energy relationships suggested by Abraham, Koppel, Palm, and Taft also afforded very good correlation coefficient (R2 values), showing the importance of cumulative effect of solvent properties. Besides these features, the negative entropies of activation (?S#) suggest greater solvation in the transition state. Isokinetic temperature (β) values for different protocols were very close to the experimental temperature range (303-323 K), indicating the importance of both enthalpy and entropy factors in controlling the reaction.
Synthesis and Structure-Activity Relationship (SAR) Studies of Novel Pyrazolopyridine Derivatives as Inhibitors of Enterovirus Replication
Xing, Yanpeng,Zuo, Jun,Krogstad, Paul,Jung, Michael E.
, p. 1688 - 1703 (2018/03/06)
A series of novel pyrazolopyridine compounds have been designed and prepared by a general synthetic route. Their activities against the replication of poliovirus-1, EV-A71, and CV-B3 enteroviruses were evaluated. The comprehensive understanding of the structure-activity relationship was obtained by utilizing the variation of four positions, namely, N1, C6, C4, and linker unit. From the screened analogues, the inhibitors with the highest selectivity indices at 50% inhibition of viral replication (SI50) were those with isopropyl at the N1 position and thiophenyl-2-yl unit at C6 position. Furthermore, the C4 position offered the greatest potential for improvement because many different N-aryl groups had better antiviral activities and compatibilities than the lead compound JX001. For example, JX040 with a 2-pyridyl group was the analogue with the most potent activity against non-polio enteroviruses, and JX025, possessing a 3-sulfamoylphenyl moiety, had the best activity against polioviruses. In addition, analogue JX037, possessing a novel pyrazolopyridine heterocycle, was also shown to have good antienteroviral activity, which further enlarges the compound space for antienteroviral drug design.
Potassium Periodate/NaNO2/KHSO4-Mediated Nitration of Aromatic Compounds and Kinetic Study of Nitration of Phenols in Aqueous Acetonitrile
Sriram, Y. Hemanth,Fatima, Touheeth,Rajanna,Kumar, M. Satish,Raju, R. Madhusudan
supporting information, p. 622 - 632 (2017/06/30)
Synthesis and kinetics of potassium periodate(KIO4)/NaNO2/KHSO4)-initiated nitration of aromatic compounds have been studied in aqueous acetonitrile medium. Synthesis of nitroaromatic compounds is achieved under conventional and solvent-free microwave conditions. Reaction times in microwave-assisted reaction are comparatively less than in conventional reaction. The reaction kinetics for the nitration of phenols in aqueous bisulfate and acetonitrile medium indicated first-order dependence on [phenol], [NaNO2], and [KIO4]. An increase in [KHSO4] accelerated the rate of nitration under otherwise similar conditions. The rate of nitration increased in the solvent of high dielectric media (solvents with high dielectric constant (D)). Observed results were in accordance with Amis and Kirkwood plots [log k′ vs. (1/D) and [(D ? 1)/(2D + 1)]. These observations probably indicate the participation of anionic species and molecular or (dipolar) species in the rate-determining step. In addition, the plots of (log k′) versus volume% of organic solvent were also linear, which probably indicate the importance of both electrostatic and nonelectrostatic forces, solvent–solute interactions during nitration of phenols. Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, but results could not be quantitatively correlated with Hammett's equation and depicted deviations from linearity. These deviations could probably be attributed to cumulative effects arising inductive, resonance, and steric effects. Leffler's plot (ΔH# vs. ΔS#) was found linear indicating the compensation (cumulative) effect of both enthalpy and entropy parameters in controlling the mechanism of nitration.
Total synthesis of heronapyrrole C
Ding, Xiao-Bo,Furkert, Daniel P.,Capon, Robert J.,Brimble, Margaret A.
supporting information, p. 378 - 381 (2014/04/03)
A flexible total synthesis of the 2-nitropyrrole-derived marine natural product, (+)-heronapyrrole C, is reported. The approach is based on regioselective access to key building blocks containing the rare 4-substituted 2-nitropyrrole motif. Sharpless asymmetric epoxidation and dihydroxylation and a Shi epoxidation were used to introduce the five stereogenic centers of the bis-THF-diol side chain. The N-benzoyloxymethyl (Boz) protecting group was crucial for functionalization of the 2-nitropyrrole moiety and enabling final deprotection under mild conditions.
Highly chemoselective nitration of aromatic amines using the Ph3P/Br2/AgNO3 system
Iranpoor, Nasser,Firouzabadi, Habib,Nowrouzi, Najmeh,Firouzabadi, Dena
, p. 6879 - 6881 (2007/10/03)
The use of PPh3/Br2/AgNO3 provides a new reagent system for the novel and highly chemoselective nitration of aromatic amines under mild reaction conditions.
A mild and efficient method for the mononitration of aromatic compounds by cerium (III) ammonium nitrate in acetic anhydride
Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
, p. 497 - 499 (2007/10/03)
A mild and efficient method for the mononitration of aromatic and olefinic compounds is described. This method is especially useful for active substrates.
N-(Triisopropylsilyl)pyrrole. A Progenitor "Par Excellence" of 3-Substituted Pyrroles
Bray, Brian L.,Mathies, Peter H.,Naef, Reto,Solas, Dennis R.,Tidwell, Thomas T.,et al.
, p. 6317 - 6328 (2007/10/02)
A very effective strategy has been devised for the synthesis of 3-substituted pyrroles based on the use of the triisopropylsilyl (TIPS) moiety as a sterically demanding nitrogen substituent to obstruct the attack of electrophilic reagents at the α positions. 1-(Triisopropylsilyl)pyrrole (1) undergoes highly preferential kinetic electrophilic substitution at the β position with a variety of electrophiles (Br+, I+, NO2+, RCO+, etc.) and fluoride ion induced desilylation of the products provides the corresponding 3-substituted pyrroles in good overall yields.Competitive trifluoroacetylation experiments demonstrate that substitution of TIPS-pyrrole at the α positions is decelerated by a factor of >104, vs pyrrole at the same sites, without affecting reactivity at the β positions. 1-(Triisopropylsilyl)-3-bromopyrrole (2) is readily converted into the 3-lithio compound 44 by bromine-lithium interchange with alkyllithium reagents.This previously unavailable, formal equivalent of 3-lithiopyrrole is itself an excellent source of a wide range of β-substituted pyrroles, many of which would not be directly preparable from 1.TIPS-pyrrole can be 3,4-dihalogenated and these compounds undergo sequential halogen-metal interchange trapping reactions.This process is exemplified by an efficient, three-step synthesis of the antibiotic verrucarin E (63) from the dibromo compound (5).
PYRROLE CHEMISTRY XXV: A SIMPLIFIED SYNTHESIS OF SOME 3-SUBSTITUTED PYRROLES
Xu, Ru Xun,Anderson, Hugh J.,Gogan, Niall J.,Loader, Charles E.,McDonald, Robert
, p. 4899 - 4900 (2007/10/02)
A new synthesis is reported which allows the rapid preparation in good yield of 3-aroyl-, 3-acetyl- and 3-nitro- pyrroles from pyrrole utilizing the 1-benzenesulfonyl group as a blocking group.
