- On the Regioselectivity of the Gould–Jacobs Reaction: Gas-Phase Versus Solution-Phase Thermolysis
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A detailed investigation of the regioselectivity in the thermal cyclization of (pyridyl)aminomethylenemalonates both in the gas- and solution phase is presented. Flash vacuum pyrolysis (FVP) as a gas-phase thermolysis technique is used to study the Gould–Jacobs reaction at temperatures between 450–650 °C, while different solution-phase heating techniques (reflux, microwave, and continuous flow) were employed at 260–350 °C. Depending on the position of the substituent in the pyridine moiety and the applied thermolysis technique, the regioselectivity of the cyclization can be controlled either in favor of the kinetic (pyridopyrimidinone) or the thermodynamic (naphthyridinone) product. Under FVP conditions, 6-substituted pyridopyrimidinones were obtained in high regioselectivity, which was not demonstrated before under standard Gould–Jacobs reaction conditions. DFT calculations have been additionally performed to provide further insights into the mechanistic pathways of this specific Gould–Jacobs reaction.
- Boese, A. Daniel,Dallinger, Doris,Darvas, Ferenc,Hartmann, Peter E.,Kappe, C. Oliver,Sipos, Gellért,Wernik, Michaela
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p. 7051 - 7061
(2020/11/30)
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- Design,: In silico studies, and synthesis of new 1,8-naphthyridine-3-carboxylic acid analogues and evaluation of their H1R antagonism effects
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New 1,8-naphthyridine-3-carboxylic acid derivatives were designed, synthesized and evaluated for their in vivo antihistaminic activity on guinea pig trachea by using chlorpheniramine as the standard drug. It was found that compound 5a1 displayed a promising bronchorelaxant effect in conscious guinea pigs using the in vivo model. A molecular docking study was performed to understand the molecular interaction and binding mode of the compounds in the active site of the H1 receptor. Furthermore, in silico computational studies were also performed to predict the binding modes and pharmacokinetic parameters of these derivatives. Prior to the start of experimental lab work, PASS software was used to predict the biological activities of these compounds. An in silico PASS, Swiss ADME assisted docking approach was found to be suitable to derive and synthesize effective antihistaminic agents for the present study.
- Gurjar, Vinod Kumar,Pal, Dilipkumar
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p. 13907 - 13921
(2020/04/24)
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- MODULATORS OF STIMULATOR OF INTERFERON GENES (STING)
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The present invention relates to compounds of formula (I) and salts, stereoisomers, tautomers or N-oxides thereof that are useful as modulators of STING (Stimulator of Interferon Genes). The present invention further relates to the compounds of formula (I) for use as a medicament and to a pharmaceutical composition comprising said compounds.
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Page/Page column 74-75
(2020/01/08)
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- Synthesis, biological evaluation, and molecular modeling studies of new 1,3,4-oxadiazole- and 1,3,4-thiadiazole-substituted 4-oxo-4H-pyrido[1,2-a] pyrimidines as anti-HIV-1 agents
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A new series of 4-oxo-4H-pyrido[1,2-a]pyrimidine derivatives containing 1,3,4-oxadiazole and 1,3,4-thiadiazole rings as a part of the metal chelation motif were synthesized and evaluated for their in vitro anti-HIV-1 activity. Most of the tested compounds displayed moderate inhibitory properties against HIV-1 virus (NL4-3) in Hela cell cultures. Compounds 11e and 11b exhibited the highest activity among the synthesized compounds with inhibition rate of 51 and 48 % at concentration of 100 μM, respectively. Molecular docking study using the later crystallographic data available for PFV integrase (IN) showed that the designed compounds bind into the active site of IN such that the keto oxygen atom at position of C-4 and nitrogen atom of thiadiazole or oxadiazole ring moiety chelate the Mg2+ ion. Our results also showed that all tested compounds presented no significant cytotoxicity at concentration of 100 μM. Therefore, these compounds can provide a very good basis for the development of new hits.
- Hajimahdi,Zarghi,Zabihollahi,Aghasadeghi
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p. 2467 - 2475
(2013/07/26)
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- A simple and efficient synthesis of novel naphthyridine-1-H-pyrazole-4- carboxylic acid esters/carbaldehydes using Vilsmeier-Haack reagent
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The reaction of hydrazide 4 with β-keto esters 5 gave hydrazones 6. Cyclization of 6 with Vilsmeier-Haack reagent (DMF-POCl3 ) for 20 min at room temperature gave 1-(4-oxo-1,4-dihydro-[ 1 ,8]naphthyridine-3-carbonyl)- 1 H -pyrazole-4-carboxylic acid ethyl esters 7. The treatment of 4 with substituted acetophenones 8 yielded the corresponding hydrazones 9 of substituted aceto phenones. The treatment of 9 with Vilsmeier-Haack reagent (DMF-POCl3) for 30 min at room temperature gave product 10, the reaction of which with (diacetoxyiodo)benzene in ethanol at room temperature for 12 h in the presence of molecular iodine furnished 7.
- Chaitanya, Muggu V.S.R.K.,Dubey, Pramod K.
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- Pyrido[1,2-a]pyrimidin-4-ones as antiplasmodial falcipain-2 inhibitors
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Plasmodium falciparum cysteine protease falcipain-2 (FP-2) is a promising target for antimalarial chemotherapy and inhibition of this protease affects the growth of parasite adversely. A series of pyrido[1,2-a]pyrimidin-4-ones were synthesized and evaluat
- Mane,Li,Huang,Gupta,Nadkarni,Giridhar,Naik,Yadav
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p. 6296 - 6304
(2012/11/13)
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- Highly efficient thermal cyclization reactions of alkylidene esters in continuous flow to give aromatic/heteroaromatic derivatives
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Intramolecular thermal cyclization and benzannulation reactions of the Gould-Jacobs and Conrad-Limpach types were performed in a designed continuous flow reactor system at temperatures in the range of 300-360°C and under high pressure conditions (100-160 bar) with very short residence times (0.45-4.5 min) in tetrahydrofuran as a low-boiling point solvent. Substituted heteroaromatic compounds including pyridopyrimidinones and hydroxyquinolines were synthesized in moderate to high yields. Application of the reaction conditions also allows the synthesis of naphthol and biphenyl derivatives. The procedure involves an easy work-up and the non-batchwise preparative synthesis method is suitable for automation.
- Lengyel, László,Nagy, Tibor Zs.,Sipos, Gellért,Jones, Richard,Dormán, Gy?rgy,ürge, László,Darvas, Ferenc
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experimental part
p. 738 - 743
(2012/03/08)
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- Efficient synthesis of novel 3-[5-(1H-benzimidazol-2-ylmethanesulfonyl)-4- phenyl-4H-(1,2,4)triazol-3-Yl]-1H-(1,8)naphthyridin-4-one derivatives
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of 1,4-dihydro-4-oxo-1,8-naphthyridine-3-carbohydrazide (4) with substituted phenyl isothiocyanates (5) in ethanol under reflux for 30 min gave thiosemicarbazide derivatives 6, which on cyclization in 2N NaOH under refluxing conditions for 1 h resulted in 3-(5-mercapto- 4-phenyl-4H-1,2,4-triazol-3-yl)- 1,8-naphthyridin-4(1H)-one (7). Alternatively, 7 could also be prepared from following sequence of reactions, i.e., 4→8→7. In another sequence of reactions, condensation of 7 with chloroacetic acid in dimethylformamide (DMF) and K2CO3 as a mild base at 120 °C for 2 h resulted in 2-((5-(1,4-dihydro-4-oxo-1,8-naphthyridin-3-yl)-4-phenyl-4H-1,2,4-triazol-3-yl) sulfanyl)acetic acid (10). The latter, on reaction with substituted o-phenylenediamine (11) in 6N HCl for 4 h yielded 3-(5-((1H-benzo[d]imidazol-2- yl)methylthio)-4-phenyl-4H-1,2,4-triazol-3-yl)-1,8-naphthyridin-4(1H)-one (12). Alternatively, 12 could also be prepared by reacting 7 with 13 in DMF and K 2CO3 as a mild base at 120 °C for 2 h, followed by oxidation with H2O2 resulting in the corresponding sulfonyl derivatives 14. Copyright
- Venkateshwarlu,Chaitanya,Dubey
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scheme or table
p. 711 - 721
(2012/06/29)
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- A rapid and convenient synthesis of naphthyridinoyl pyrazolidinones under microwave irradiation condition
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Microwave-assisted synthesis of naphthyridinoylpyrazolidinones (7a-7j) has been achieved rapidly via the reaction of naphthyridine hydrazide (4) with different β-keto esters and ethoxymethylenemalonic ester (EMME) (5a-5e). Initially, the reaction of naphthyridine hydrazide (4) with various β-keto esters under microwave irradiation for 5 mins at 130oC results in the formation of condensed products 6a-6j. This condensation was followed by cyclization, also, in diphenyl ether under microwave irradiation for 10 mins at 230-250oC, yielding the corresponding cyclized products 7a-7j. Alternatively, both reactants 4 and each of the β -keto esters/EMME (5a-5e) were treated in diphenyl ether under microwave irradiation for 15 mins at 230-250oC giving the target molecules 7a-7j as one-pot reaction in good yields.
- Chaitanya, Muggu V.S.R.K.,Dubey, Pramod K.
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scheme or table
p. 368 - 374
(2012/08/28)
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- Synthesis of novel napththyridines as potential antibacterial agents
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The reaction of 2-aminopyridine (1) with ethoxymethylenemalonic ester gave 4-ethoxy-3-oxo-2-(pyridine-2-yl aminomethylene)-butyric acid ethyl ester (2) which on cyclization in the presence of hot PPA gave 4-oxo-1,4-dihydro-[1,8] naphthyridine-3-carboxylic
- Chaitanya,Dubey
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p. 105 - 108
(2013/09/23)
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- 2,2-Bis(ethoxycarbonyl)vinyl (BECV) as a versatile amine protecting group for selective functional-group transformations
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A 2,2-Bis(ethoxycarbonyl) vinyl- (BECV) group was used for the selective protection of amines at room temperature in the presence of potentially interfering functional groups such as OH, SH, COOH as well as other NH 2 groups. Several functional group transformations such as esterification, O-alkylation, O-acylation, N-alkylation, N-acylation, S-alkylation can selectively be carried out in the presence of the BECV group. The selective deprotection of the BECV group was achieved in a short time using ethylenediamine at room temperature while several other functional groups such as benzoate, aliphatic esters, amides and ethers remain intact. The BECV group shows orthogonal stability against the common protecting groups such as Fmoc, Cbz and Boc.
- Ilangovan, Andivelu,Kumar, Rajendran Ganesh
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supporting information; experimental part
p. 2938 - 2943
(2010/07/02)
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- A facile and convenient synthesis of naphthyridinoyl pyrazoles
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The reaction of naphthyridine hydrazide (4) with each of the different β-keto esters like ethyl 2-chloroacetoacetate (5), ethyl benzoylacetate (6) and ethyl 4-chloroacetoacetate (7) and with ethoxymethylenemalonic ester (8), independently, in ethanol, resulted in the formation of condensed products 2-chloro-3-[4-oxo-1,4-dihydro-[1,8] naphthyridine-3-carbonyl hydrazono]-butyric acid ethyl ester (9), 3-[(4-oxo-1,4-dihydro-[1,8] naphthyridine-3-carbonyl)- hydrazono]-3-phenyl propionic acid ethyl ester (10), 4-chloro-3-[(4-oxo-1,4- dihydro-[1,8] naphthyridine-3-carbonyl)-hydrazono]-butyric acid ethyl ester (11) and 2-[N-(6-bromo-4-oxo-1,4-diydro-[1,8] naphtyiridine-3-carbonyl- hydrazinomethylene)-malonic acid diethyl ester] (12) respectively. Each of these on heating with diphenyl ether yielded the corresponding cyclized products 3-(4-chloro-3-methyl-5-oxo-4,5-dihydro-pyrazole-1-carbonyl)-1H-[1,8] naphthyridin-4-ohe (13), 3-(5-oxo-3-phenyl-4,5-dihydro-pyrazole-1-carbonyl)-1H- [1,8] naphthyridine-4-one (14), 3-(3-chloromethyl-5-oxo-4,5-dihydropyrazole-1- carbonyl)-1 H-[1,8] naphthyridine-4-one (15) and 3-(4-chloro-3-methyl-5-oxo-4,5- dihydropyrazole-1-carbonyl)-1H-[1,8] naphthyridin-4-one (16). Alternatively, treatment of naphthyridine hydrazide (4) with each of the β-keto esters 5,6 & 7 and with EMME (8) directly in diphenylether at 2507deg; as one-pot reaction, gave the final products 13,14,15 & 16 in good yields.
- Chaitanya,Dubey
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p. 109 - 112
(2013/09/23)
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