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Artículos de revistas sobre el tema "Nitro-4H"

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Autor: Grafiati

Publicado: 18 de mayo de 2024

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1

Nagaraju, Pallava, Pannala Padmaja y Pedavenkatagari Narayana Reddy. "Microwave-assisted One-pot Synthesis of 7-Dimethylamino-4-Aryl-2- methylamino-3-nitro-4H-chromenes". Letters in Organic Chemistry 16, n.º 6 (23 de abril de 2019): 468–73. http://dx.doi.org/10.2174/1570178615666181025114748.

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4-Aryl-2-amino-4H-chromenes possessing N,N-dimethylamino group have been reported as potential anticancer drugs. Despite few synthetic methods reported in the literature for their synthesis, there appear to be no reports on the direct use of N,N-dimethyl-3-aminophenol for the synthesis of 4- aryl-2-methylamino-3-nitro-4H-chromenes. One-pot condensation of N,N-dimethyl-3-aminophenol, aromatic aldehydes and (E)-N-methyl-1-(methylthio)-2-nitro-ethenamine was carried out using MW irradiation to get the 4-aryl-2-methylamino-3-nitro-4H-chromenes under catalyst-free conditions. This transformation presumably occurs via o-quinone methide formation, Michael addition-intramolecular O-cyclization-elimination sequence of reactions creating new two C-C bonds and one C-O bond. Various substituted aromatic aldehydes reacted smoothly with N,N-dimethyl-3-aminophenol and (E)-Nmethyl- 1-(methylthio)-2-nitro-ethenamine to give the corresponding 4-aryl-2-methylamino-3-nitro-4Hchromenes in good yields. We have developed a one-pot three component condensation of N,Ndimethyl- 3-aminophenol, aromatic aldehyde and NMSM for the synthesis of N,N-dimethylamino substituted 4-aryl-2-methylamino-3-nitro-4H-chromenes in good yields. The significant features of this reaction include catalyst-free, solvent free, no column chromatographic purification, short reaction time and good yields.

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2

Vlachou, Evangelia-Eirini N., Thomas D. Balalas, Dimitra J. Hadjipavlou-Litina, Konstantinos E. Litinas y Matina Douka. "2,9-Dimethyl-4H-oxazolo[5’,4’:4,5]pyrano[3,2-f]quinolin-4-one". Molbank 2023, n.º 1 (17 de febrero de 2023): M1591. http://dx.doi.org/10.3390/m1591.

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The new 2,9-dimethyl-4H-oxazolo[5’,4’:4,5]pyrano[3,2-f]quinolin-4-one was successfully prepared through the three-component iodine-catalyzed reaction of n-butyl vinyl ether with the new 8-amino-2-methyl-4H-chromeno[3,4-d]oxazol-4-one. The latter was prepared by the reduction of 2-methyl-8-nitro-4H-chromeno[3,4-d]oxazol-4-one with Pd/C in a hydrogen atmosphere. The above nitro compound was synthesized by the condensation of N-(4-hydroxy-6-nitro-2-oxo-2H-chromen-3-yl)acetamide with P2O5 under microwave irradiation. The above acetamide derivative was prepared during the nitration of 2-methyl-4H-chromeno[3,4-d]oxazol-4-one with H2SO4 and KNO3. The structure of the newly synthesized compounds was confirmed by FT-IR, LC-MS, 1H-NMR, and 13C-NMR analyses. Preliminary biological tests show significant anti-lipid peroxidation activity for the title compound and the other synthesized new intermediates, as well as interesting soybean lipoxygenase inhibition for acetamide 2 (IC50 55 μM) and nitro-compound 3 (IC50 27 μM).

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3

P, Nefisath, Vishwanatha P y Sudhakar Y. N. "Synthesis and Characterization of Benzoxazinone Derivatives". Mapana Journal of Sciences 17, n.º 2 (16 de agosto de 2021): 47–51. http://dx.doi.org/10.12723/mjs.45.4.

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The present work reports synthesis and characterization of different benzoxazinone derivatives. 2-methyl-7-nitro-4H-3,1-benzoxazin-4-one was prepared by refluxing 4- nitroanthranilic acid with acid anhydride. Derivatives of 2-methyl-7-nitro-4H-3,1-benzoxazin-4-one were synthesized by condensation of it with different anilines. Elemental analysis and NMR spectral studies were used to confirm the formation of compounds.

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4

Vishnupriya, R., J. Suresh, S. Sivakumar y R. Ranjith Kumar. "N—H...O and N—H...N interactions in three pyran derivatives". Acta Crystallographica Section C Crystal Structure Communications 69, n.º 6 (2 de mayo de 2013): 642–46. http://dx.doi.org/10.1107/s0108270113010676.

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The three pyran structures 6-methylamino-5-nitro-2,4-diphenyl-4H-pyran-3-carbonitrile, C19H15N3O3, (I), 4-(3-fluorophenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile, C19H14FN3O3, (II), and 4-(4-chlorophenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile, C19H14ClN3O3, (III), differ in the nature of the aryl group at the 4-position. The heterocyclic ring in all three structures adopts a flattened boat conformation. The dihedral angle between the pseudo-axial phenyl substituent and the flat part of the pyran ring is 89.97 (1)° in (I), 80.11 (1)° in (II) and 87.77 (1)° in (III). In all three crystal structures, a strong intramolecular N—H...O hydrogen bond links the flat conjugated H—N—C=C—N—O fragment into a six-membered ring. In (II), molecules are linked into dimeric aggregates by N—H... O(nitro) hydrogen bonds, generating anR22(12) graph-set motif. In (III), intermolecular N—H...N and C—H...N hydrogen bonds link the molecules into a linear chain pattern generatingC(8) andC(9) graph-set motifs, respectively.

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5

Safieh, Kayed A. Abu, Feda’a S. Al-Masri, Mikdad T. Ayoub, Mustafa M. El-Abadelah y Wolfgang Voelter. "Synthesis of Some 1,3-Dimethyl-6-substituted-1H-pyrazolo[3,4-b]pyrazin-5(4H)-ones". Zeitschrift für Naturforschung B 66, n.º 11 (1 de noviembre de 2011): 1136–40. http://dx.doi.org/10.1515/znb-2011-1109.

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A series of new 6-substituted-1,3-dimethyl-1H-pyrazolo[3,4-b]pyrazin-5(4H)-ones (13a - e) and 1,3-dimethyl-5a,6a,7,8-tetrahydro-1H-pyrazolo[4,3-e]pyrrolo[1,2-a]pyrazin-5(4H)-one (15) have been synthesized. The synthetic strategy involves direct interaction of D,L-α-amino acids with 5- chloro-1,3-dimethyl-4-nitro-1H-pyrazole (10) to produce the respective N-(1,3-dimethyl-4-nitro-1Hpyrazol- 5-yl) D,L-α-amino acids 11a - e and 14. The latter compounds underwent reductive lactamization to deliver the corresponding target heterocyclic systems 13a - e and 15

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6

Maheshwari, Monika y Anju Goyal. "SYNTHESIS AND MICROBIOLOGICAL EVALUATION OF 1-(4-METHYL-6-NITRO-2H-BENZO[B] [1,4]THIAZINE-3(4H)-YLIDENE)HYDRAZINE-1,1-DIOXIDE DERIVATIVES". Asian Journal of Pharmaceutical and Clinical Research 10, n.º 9 (1 de septiembre de 2017): 348. http://dx.doi.org/10.22159/ajpcr.2017.v10i9.19093.

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Objective: The objective of this work was to synthesize and evaluate antimicrobial properties of 1-(4-methyl-6-nitro-2H-benzo[b][1,4]thiazine- 3(4H)-ylidene)hydrazine-1,1-dioxide derivatives.Methods: These new compounds were synthesized by methylation in 4-N and reacted with hydrazine derivatives and oxidized at the sulfur atom by 30% hydrogen peroxide to obtain sulfones. All the synthesized compounds were evaluated for antimicrobial activity using the disc diffusion method.Results: The Fourier transform infrared, 1H nuclear magnetic resonance (NMR), 13CNMR, and mass studies confirm the synthesis of some new 1-(4-methyl- 6-nitro-2H-benzo[b][1,4]thiazine-3(4H)-ylidene)hydrazine-1,1-dioxide derivatives. Compound 6f showed the potent antimicrobial activity.Conclusion: Result obtained in this research work clearly indicated that the compound 6f having methyl at 2 position and nitro groups at 2′ and 4′ position showed the most potent antimicrobial activity.

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7

Li, Xuanxuan, Shengyi Zhuang, Xinxin Fang, Ping Liu y Peipei Sun. "Addition of nitrogen dioxide to carbon–carbon double bond followed by a cyclization to construct nitromethylated isoquinolinediones". Organic & Biomolecular Chemistry 15, n.º 8 (2017): 1821–27. http://dx.doi.org/10.1039/c6ob02797k.

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8

Tao, Guo-Hong, Yong Guo, Damon A. Parrish y Jean'ne M. Shreeve. "Energetic 1,5-diamino-4H-tetrazolium nitro-substituted azolates". Journal of Materials Chemistry 20, n.º 15 (2010): 2999. http://dx.doi.org/10.1039/b925267c.

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9

Korotaev, V. Yu, I. B. Kutyashev, A. Yu Barkov y V. Ya Sosnovskikh. "Recent advances in the chemistry of 3-nitro-2H- and 3-nitro-4H-chromenes". Russian Chemical Reviews 88, n.º 1 (3 de enero de 2019): 27–58. http://dx.doi.org/10.1070/rcr4840.

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10

Kovalevsky, A. Yu y I. I. Ponomarev. "2-Methyl-7-nitro-4H-3,1-benzoxazin-4-one". Acta Crystallographica Section C Crystal Structure Communications 55, n.º 11 (15 de noviembre de 1999): IUC9900136. http://dx.doi.org/10.1107/s0108270199098431.

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11

Surya Prakash Rao, H., K. Geetha y M. Kamalraj. "Synthesis of 4-(2-hydroxyaryl)-3-nitro-4H-chromenes". Tetrahedron 67, n.º 42 (octubre de 2011): 8146–54. http://dx.doi.org/10.1016/j.tet.2011.08.045.

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12

Gnanasekaran, Krishna, John Hiett y Richard Bunce. "6-Nitro-4H-benzo[d][1,3]thiazin-2-amine". Molbank 2016, n.º 2 (16 de mayo de 2016): M899. http://dx.doi.org/10.3390/m899.

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13

Khan, Zulfiqar Ali, Khalid M. Khan y Shazia Anjum. "7-Nitro-2-phenyl-4H-3,1-benzoxazin-4-one". Acta Crystallographica Section E Structure Reports Online 63, n.º 11 (3 de octubre de 2007): o4226—o4227. http://dx.doi.org/10.1107/s1600536807046168.

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The title compound, C14H8N2O4, was synthesized by reacting p-nitroanthranilic acid and benzoyl chloride at ambient temperature. The structure is stabilized by an intramolecular C—H...O hydrogen bond and an intermolecular C—H...O hydrogen bond. Additionally, weak π–π stacking interactions [centroid–centroid distance 3.6 (17) Å] between adjacent molecules further stabilize the crystal structure and form parallel layers along the b axis.

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14

Yennawar, Hemant, Aaron S. Cali, Yiwen Xie y Lee J. Silverberg. "Crystal structures of 2-(4-nitrophenyl)-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one and 2-(2-nitrophenyl)-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one". Acta Crystallographica Section E Crystallographic Communications 71, n.º 4 (25 de marzo de 2015): 414–17. http://dx.doi.org/10.1107/s2056989015004545.

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The crystal structures are reported of the isomeric compounds 2-(4-nitrophenyl)-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one, (I), and 2-(2-nitrophenyl)-3-phenyl-2,3-dihydro-4H-1,3-benzothiazin-4-one, (II), both C20H14N2O3S, being thepara-nitro andortho-nitro forms, respectively, themeta-form of which is known [Yennawaret al.(2013).Acta Cryst.E69, o1679]. The six-membered thiazone ring fused with a benzene ring displays a screw-boat conformation with a total puckering amplitude of 0.627 (1) Å in (I), and a near screw-boat conformation with a total puckering amplitude of 0.600 (1) Å in (II). The dihedral angles between the planes of the substituent nitrophenyl and phenyl and rings with the benzene ring of the parent benzothiazone moiety are 75.93 (5) and 82.61 (5)° [in (I)], and 76.79 (6) and 71.66 (6)° [in (II)]. Weak intermolecular C—H...O hydrogen-bonding interactions between aromatic H-atom donors and both a nitro-O atom and a thiazone O-atom acceptor in (I) and a thiazone O atom in (II) are present, forming in (I) a centrosymmetric 22-membered cyclic dimer which is extended through a similar inversion-related 14-membered cyclic hydrogen-bonding association into a zigzag chain structure extending alongc. In (II), a single intermolecular C—H...O hydrogen bond gives a chain structure extending alongb. In addition, weak C—H...π interactions are present in both structures [minimum C...ring-centroid separations = 3.630 (2) and 3.581 (2) Å, respectively].

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15

Kraľovičová, Eva, Alžbeta Krutošíková, Jaroslav Kováč y Miloslava Dandárová. "Electrophilic substitution reactions of furo[3,2-b]pyrrole derivatives". Collection of Czechoslovak Chemical Communications 51, n.º 1 (1986): 106–11. http://dx.doi.org/10.1135/cccc19860106.

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Formylation of ethyl 4H-furo[3,2-b]pyrrole-5-carboxylate and its N-methyl analogue afforded the 2-formyl products Ia,b which on nitration yielded 2-nitro derivatives IIc,d. Formylation, nitration, Mannich reaction, and copulation of the starting products, having position 2 occupied by an aryl, took place at the pyrrole ring.

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16

Ishikawa, Yoshinobu. "6-Chloro-8-nitro-4-oxo-4H-chromene-3-carbaldehyde". Acta Crystallographica Section E Structure Reports Online 70, n.º 5 (12 de abril de 2014): o547. http://dx.doi.org/10.1107/s1600536814007788.

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In the title compound, C10H4ClNO5, the non-H atoms of the 6-chlorochromone unit are coplanar (r.m.s. deviation = 0.017 Å) with the largest deviation from the mean plane [0.031 (2) Å] being found for the C=O C atom. The nitro group (NO2) is inclined to the chromone unit mean plane by 13.3 (2) °. The formyl group is also twisted with respect to the attached ring [C—C—C—O torsion angles = 10.8 (4) and −171.8 (2)°]. In the crystal, molecules are linked via C-H...O hydrogen bonds forming slab-like networks lying parallel to (-301). The slabs are linked by π–π interactions involving the benzene rings of the chromone units [centroid–centroid distance = 3.770 (3) Å].

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17

Marshalkin, V. N., A. V. Samet y V. V. Semenov. "Synthesis of 2-amino-5-nitro-4H-pyran-3-carbonitriles". Chemistry of Heterocyclic Compounds 34, n.º 12 (diciembre de 1998): 1409–11. http://dx.doi.org/10.1007/bf02317810.

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18

Tiekink, Edward R. T. y James L. Wardell. "2-(2-Amino-4-nitrophenyl)-7-nitro-4H-3,1-benzoxazin-4-one". Acta Crystallographica Section E Structure Reports Online 70, n.º 2 (18 de enero de 2014): o158—o159. http://dx.doi.org/10.1107/s1600536814000609.

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In the title compound, C14H8N4O6, the benzoxazin-4-one fused-ring system (r.m.s. deviation = 0.018 Å) is coplanar with the attached benzene ring [dihedral angle = 0.81 (4)°], there being an intramolecular N—H...N hydrogen bond between them. Each nitro group is twisted out of the plane of the attached benzene ring [O—N—C—C torsion angles = 167.94 (11) and 170.38 (11)°]. In the crystal, amine–nitro N—H...O hydrogen bonds lead to centrosymmetric dimeric aggregates that are connected into a three-dimensional architecture by oxazinyl–nitro C—H...O and π–π interactions [inter-centroid distance between the oxazinyl and terminal benzene rings = 3.5069 (7) Å].

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19

Gayathri, D., D. Velmurugan, K. Ravikumar, K. Geetha y H. Surya Prakash Rao. "2-[2-(Methylamino)-3-nitro-4H-chromen-4-yl]phenyl acetate". Acta Crystallographica Section E Structure Reports Online 63, n.º 5 (13 de abril de 2007): o2300—o2302. http://dx.doi.org/10.1107/s1600536807015681.

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20

Gayathri, D., D. Velmurugan, K. Ravikumar, K. Geetha y H. Surya Prakash Rao. "N,6-Dimethyl-4-(methylsulfanyl)-3-nitro-4H-chromen-2-amine". Acta Crystallographica Section E Structure Reports Online 62, n.º 5 (21 de abril de 2006): o1961—o1963. http://dx.doi.org/10.1107/s1600536806013675.

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In the title compound, C12H14N2O3S, the pyran ring adopts an envelope conformation. An N—H...O hydrogen bond generates an S(6) ring motif and intermolecular C—H...O interactions generate a centrosymmetric R 2 2(14) dimer.

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21

Dauzonne, Daniel y Cyrille Grandjean. "Synthesis of 2-Aryl-3-nitro-4H-1-benzopyran-4-ones". Synthesis 1992, n.º 07 (1992): 677–80. http://dx.doi.org/10.1055/s-1992-26198.

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22

Rao, H. Surya Prakash, K. Geetha y M. Kamalraj. "ChemInform Abstract: Synthesis of 4-(2-Hydroxyaryl)-3-nitro-4H-chromenes." ChemInform 43, n.º 9 (2 de febrero de 2012): no. http://dx.doi.org/10.1002/chin.201209142.

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23

Cai, Chun y Ru-Shuang Zhou. "C–H Amination of Nitro Azaheterocyclic Compounds by Vicarious Nucleophilic Substitution". Synlett 33, n.º 01 (19 de octubre de 2021): 88–92. http://dx.doi.org/10.1055/a-1672-7285.

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AbstractVarious nitro azaheterocyclic compounds were subjected to C–H amination by vicarious nucleophilic substitution with 4H-1,2,4-triazol-4-amine (ATA). The aminated products were characterized by NMR, mass spectroscopy, and single-crystal X-ray diffraction analyses. The substrates examined gave moderate to excellent yields (30–88%) and showed good regioselectivities. This protocol offers the advantages of mild conditions, a short reaction time (2–4 hours), and an inexpensive, commercially available, and less-toxic amination reagent; moreover, no additional catalyst or reagent is needed. A possible reaction mechanism is discussed.

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24

Muthukumaran, J., A. Parthiban, P. Manivel, H. Surya Prakash Rao y R. Krishna. "6-Methoxy-N-methyl-3-nitro-4-nitromethyl-4H-chromen-2-amine". Acta Crystallographica Section E Structure Reports Online 67, n.º 5 (29 de abril de 2011): o1276—o1277. http://dx.doi.org/10.1107/s1600536811015595.

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25

Muthukumaran, J., A. Parthiban, P. Manivel, H. Surya Prakash Rao y R. Krishna. "4-[4-(Diethylamino)phenyl]-N-methyl-3-nitro-4H-chromen-2-amine". Acta Crystallographica Section E Structure Reports Online 67, n.º 6 (14 de mayo de 2011): o1395—o1396. http://dx.doi.org/10.1107/s1600536811017338.

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26

Rao, H. Surya Prakash y K. Geetha. "Nitroketene acetal chemistry: efficient synthesis of 2-amino-3-nitro-4H-chromenes". Tetrahedron Letters 50, n.º 27 (julio de 2009): 3836–39. http://dx.doi.org/10.1016/j.tetlet.2009.04.018.

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27

Muthukumaran, J., A. Parthiban, H. Surya Prakash Rao y R. Krishna. "6-Ethyl-N-methyl-3-nitro-4-nitromethyl-4H-chromen-2-amine". Acta Crystallographica Section E Structure Reports Online 68, n.º 1 (21 de diciembre de 2011): o180—o181. http://dx.doi.org/10.1107/s1600536811053554.

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28

Bhaskaran, Sundari, D. Velmurugan, K. Ravikumar, K. Geetha y H. Surya Prakash Rao. "N-Benzyl-N-[4-(methylsulfanyl)-3-nitro-4H-chromen-2-yl]amine". Acta Crystallographica Section E Structure Reports Online 62, n.º 1 (14 de diciembre de 2005): o188—o190. http://dx.doi.org/10.1107/s160053680504081x.

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29

Muthukumaran, J., A. Parthiban, M. Kannan, H. Surya Prakash Rao y R. Krishna. "6,8-Dichloro-N-methyl-3-nitro-4-nitromethyl-4H-chromen-2-amine". Acta Crystallographica Section E Structure Reports Online 67, n.º 4 (15 de marzo de 2011): o898—o899. http://dx.doi.org/10.1107/s1600536811009366.

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30

Zhang, Gang y Courtney C. Aldrich. "Macozinone: revised synthesis and crystal structure of a promising new drug for treating drug-sensitive and drug-resistant tuberculosis". Acta Crystallographica Section C Structural Chemistry 75, n.º 8 (5 de julio de 2019): 1031–35. http://dx.doi.org/10.1107/s2053229619009185.

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Mycobacterium tuberculosis (Mtb), the principal etiological agent of tuberculosis (TB), infects over one-quarter of humanity and is now the leading cause of infectious disease mortality by a single pathogen. Macozinone {2-[4-(cyclohexylmethyl)piperazin-1-yl]-8-nitro-6-(trifluoromethyl)-4H-1,3-benzothiazin-4-one, C20H23F3N4O3S} is a promising new drug for treating drug-sensitive and drug-resistant TB that has successfully completed phase I clinical trials. We report the complete spectroscopic and structural characterization by 1H NMR, 13C NMR, HRMS, IR, and X-ray crystallography. The cyclohexyl moiety is observed to be nearly perpendicular to the core formed by the 1,3-benzothiazin-4-one and piperazine groups. The central piperazine ring adopts a slightly distorted chair conformation caused by sp 2-hybridization of the nitro N atom, which donates into the electron-deficient 1,3-benzothiazin-4-one group.

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31

Eckhardt, Tamira, Richard Goddard, Christoph Lehmann, Adrian Richter, Henok Asfaw Sahile, Rui Liu, Rohit Tiwari et al. "Crystallographic evidence for unintended benzisothiazolinone 1-oxide formation from benzothiazinones through oxidation". Acta Crystallographica Section C Structural Chemistry 76, n.º 9 (21 de agosto de 2020): 907–13. http://dx.doi.org/10.1107/s2053229620010931.

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1,3-Benzothiazin-4-ones (BTZs) are a promising new class of drugs with activity against Mycobacterium tuberculosis, which have already reached clinical trials. A product obtained in low yield upon treatment of 8-nitro-2-(piperidin-1-yl)-6-(trifluoromethyl)-4H-benzothiazin-4-one with 3-chloroperbenzoic acid, in analogy to a literature report describing the formation of sulfoxide and sulfone derived from BTZ043 [Tiwari et al. (2015). ACS Med. Chem. Lett. 6, 128–133], is a ring-contracted benzisothiazolinone (BIT) 1-oxide, namely, 7-nitro-2-(piperidine-1-carbonyl)-5-(trifluoromethyl)benzo[d]isothiazol-3(2H)-one 1-oxide, C14H12F3N3O5S, as revealed by X-ray crystallography. Single-crystal X-ray analysis of the oxidation product originally assigned as BTZ043 sulfone provides clear evidence that the structure of the purported BTZ043 sulfone is likewise the corresponding BIT 1-oxide, namely, 2-[(S)-2-methyl-1,4-dioxa-8-azaspiro[4.5]decane-8-carbonyl]-7-nitro-5-(trifluoromethyl)benzo[d]isothiazol-3(2H)-one 1-oxide, C17H16F3N3O7S. A possible mechanism for the ring contraction affording the BIT 1-oxides instead of the anticipated constitutionally isomeric BTZ sulfones and antimycobacterial activities thereof are discussed.

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32

Faure, Robert, Émile-Jean Vincent, André Rousseau, Rose Maria Claramunt y José Elguero. "High resolution 13C nuclear magnetic resonance spectra of solid pyrazoles. Application to annular tautomerism". Canadian Journal of Chemistry 66, n.º 5 (1 de mayo de 1988): 1141–46. http://dx.doi.org/10.1139/v88-187.

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Carbon-13 nuclear magnetic resonance spectroscopy in the solid state (cross polarization/magic angle spinning technique) is a very suitable method for studying the annular tautomerism of pyrazoles. In all the compounds studied, the tautomerism is frozen and the signals are well resolved except for 3,5-dimethyl-4-nitro pyrazole, which shows broad signals. In the case of 4-substituted derivatives of 3(5)-methylpyrazoles, the tautomer present in the solid state is a 4-X-5 methylpyrazole. 3-Phenyl-5-methylpyrazole (4H or 4-methyl) is favoured over the 3-methyl-5-phenyl tautomer.

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33

Vishnupriya, R., J. Suresh, S. Sivakumar, R. Ranjith Kumar y P. L. Nilantha Lakshman. "4-(4-Fluorophenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile". Acta Crystallographica Section E Structure Reports Online 69, n.º 5 (10 de abril de 2013): o687—o688. http://dx.doi.org/10.1107/s1600536813009008.

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34

Narayanan, P., Jayabal Kamalraja, Paramasivam T. Perumal y K. Sethusankar. "4-(4-Bromophenyl)-2-methylamino-3-nitro-5,6,7,8-tetrahydro-4H-chromen-5-one". Acta Crystallographica Section E Structure Reports Online 69, n.º 6 (22 de mayo de 2013): o931—o932. http://dx.doi.org/10.1107/s1600536813012774.

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35

Vishnupriya, R., J. Suresh, S. Sivakumar, R. Ranjith Kumar y P. L. Nilantha Lakshman. "4-(4-Methoxyphenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile". Acta Crystallographica Section E Structure Reports Online 69, n.º 3 (28 de febrero de 2013): o451. http://dx.doi.org/10.1107/s1600536813004923.

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36

DAUZONNE, D. y C. GRANDJEAN. "ChemInform Abstract: Synthesis of 2-Aryl-3-nitro-4H-1-benzopyran-4-ones." ChemInform 23, n.º 46 (21 de agosto de 2010): no. http://dx.doi.org/10.1002/chin.199246174.

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37

Marshalkin, V. N., A. V. Samet y V. V. Semenov. "ChemInform Abstract: Synthesis of Substituted 2-Amino-5-nitro-4H-pyran-3-carbonitriles." ChemInform 30, n.º 21 (15 de junio de 2010): no. http://dx.doi.org/10.1002/chin.199921132.

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38

Starykov, Oleksiy, Jan Prokeš, Ivo Křivka y Jaroslav Stejskal. "Charge transport in polyaniline doped with 3-nitro-1,2,4-triazol-5(4H)-one". Macromolecular Symposia 212, n.º 1 (abril de 2004): 455–60. http://dx.doi.org/10.1002/masy.200450857.

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39

Edinoff, Amber N., Catherine A. Nix, Amira S. Odisho, Caroline P. Babin, Alyssa G. Derouen, Salim C. Lutfallah, Elyse M. Cornett, Kevin S. Murnane, Adam M. Kaye y Alan D. Kaye. "Novel Designer Benzodiazepines: Comprehensive Review of Evolving Clinical and Adverse Effects". Neurology International 14, n.º 3 (22 de agosto de 2022): 648–63. http://dx.doi.org/10.3390/neurolint14030053.

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As tranquilizers, benzodiazepines have a wide range of clinical uses. Recently, there has been a significant rise in the number of novel psychoactive substances, including designer benzodiazepines. Flubromazolam(8-bromo-6-(2-fluorophenyl)-1-methyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazeZpine) is a triazolo-analogue of flubromazepam. The most common effects noted by recreational users include heavy hypnosis and sedation, long-lasting amnesia, and rapid development of tolerance. Other effects included anxiolysis, muscle-relaxing effects, euphoria, loss of control, and severe withdrawals. Clonazolam, or 6-(2-chlorophenyl)-1-methyl-8-nitro-4H-[1,2,4]triazolo[4,3-α]-[1,4]-benzodiazepine, is a triazolo-analog of clonazepam. It is reported to be over twice as potent as alprazolam. Deschloroetizolam (2-Ethyl-9-methyl-4-phenyl-6H-thieno[3,2-f][1,2,4]triazolo[4,3-a][1,4]diazepine) is part of the thienodiazepine drug class, which, like benzodiazepines, stimulates GABA-A receptors. Meclonazepam ((3S)-5-(2-chlorophenyl)-3-methyl-7-nitro-1,3-dihydro-1,4-benzodiazepin-2-one) is a designer benzodiazepine with additional anti-parasitic effects. Although it has proven to be an efficacious therapy for schistosomiasis, its sedative side effects have prevented it from being marketed as a therapeutic agent. The use of DBZs has been a subject of multiple recent clinical studies, likely related to increasing presence and availability on the internet drug market and lack of regulation. Many studies have aimed to identify the prevalence of DBZs and their effects on those using them. This review discussed these designer benzodiazepines and the dangers and adverse effects that the clinician should know.

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40

Valle, María, Laura Martín, Alicia Maestro, José M. Andrés y Rafael Pedrosa. "Chiral Bifunctional Thioureas and Squaramides Grafted into Old Polymers of Intrinsic Microporosity for Novel Applications". Polymers 11, n.º 1 (21 de diciembre de 2018): 13. http://dx.doi.org/10.3390/polym11010013.

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We have prepared different polymeric chiral bifunctional thioureas and squaramides by modification of the very well-known polymers of intrinsic microporosity (PIM), specifically PIM-1 and PIM-CO-1, to be used as recoverable organocatalysts. The installation of the chiral structures into the polymers has been done in two or three steps in high yields. The catalytic activity of the resulting materials has been proved in the stereoselective nitro-Michael addition and in a cascade process, which allows the synthesis of enantioenriched 4H-chromene derivatives. Squaramide II and thiourea III have been used in six cycles maintaining their activity.

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41

Pasca, Maria Rosalia, Giulia Degiacomi, Ana Luisa de Jesus Lopes Ribeiro, Francesca Zara, Patrizia De Mori, Beate Heym, Maurizio Mirrione et al. "Clinical Isolates of Mycobacterium tuberculosis in Four European Hospitals Are Uniformly Susceptible to Benzothiazinones". Antimicrobial Agents and Chemotherapy 54, n.º 4 (19 de enero de 2010): 1616–18. http://dx.doi.org/10.1128/aac.01676-09.

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ABSTRACT The new antitubercular drug candidate 2-[2-S-methyl-1,4-dioxa-8-azaspiro[4.5]dec-8-yl]-8-nitro-6-(trifluoromethyl)-4H-1,3-benzothiazin-4-one (BTZ043) targets the DprE1 (Rv3790) subunit of the enzyme decaprenylphosphoryl-β-d-ribose 2′-epimerase. To monitor the potential development of benzothiazinone (BTZ) resistance, a total of 240 sensitive and multidrug-resistant Mycobacterium tuberculosis clinical isolates from four European hospitals were surveyed for the presence of mutations in the dprE1 gene and for BTZ susceptibility. All 240 strains were susceptible, thus establishing the baseline prior to the introduction of BTZ043 in clinical trials.

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42

Narayanan, P., Jayabal Kamalraja, Paramasivam T. Perumal y K. Sethusankar. "(4S*)-2-Methylamino-3-nitro-4-(4-nitrophenyl)-5,6,7,8-tetrahydro-4H-chromen-5-one". Acta Crystallographica Section E Structure Reports Online 69, n.º 9 (3 de agosto de 2013): o1380—o1381. http://dx.doi.org/10.1107/s1600536813021181.

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43

Narayanan, P., Jayabal Kamalraja, Paramasivam T. Perumal y K. Sethusankar. "rac-4-(4-Chlorophenyl)-2-methylamino-3-nitro-5,6,7,8-tetrahydro-4H-chromen-5-one". Acta Crystallographica Section E Structure Reports Online 69, n.º 7 (8 de junio de 2013): o1053—o1054. http://dx.doi.org/10.1107/s1600536813014530.

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44

Oskolkov, Evgenii, Tatiana Kornilova, Preciosa America Chavez, John P. Tillotson y Tatiana V. Timofeeva. "Structural (at 100 K) and DFT studies of 2′-nitroflavone". Acta Crystallographica Section E Crystallographic Communications 76, n.º 9 (7 de agosto de 2020): 1417–20. http://dx.doi.org/10.1107/s2056989020010713.

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The geometry of the title molecule [systematic name: 2-(2-nitrophenyl)-4H-chromen-4-one], C15H9NO4, is determined by two dihedral angles formed by the mean plane of phenyl ring with the mean planes of chromone moiety and nitro group, being 50.73 (5) and 30.89 (7)°, respectively. The crystal packing is determined by π–π interactions and C—H...O contacts. The results of DFT calculations at the B3LYP/6–31G* level of theory provided an explanation of the unusually large dihedral angle between the chromone moiety and the phenyl group. The electrostatic potential map on the molecular surface was calculated in order to determine the potential binding sites to receptors.

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45

Menicagli, R., C. Malanga y V. Guagnano. "3-nitro-5,6-dihydro-4H-pyran ,a latent-CHO Equivalent: A New Synthesis of Aldehydes". Tetrahedron Letters 33, n.º 20 (mayo de 1992): 2867–70. http://dx.doi.org/10.1016/s0040-4039(00)78882-4.

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46

Dinparast, Leila, Hassan Valizadeh, Esmail Vessally y Mir Babak Bahadori. "Synthesis, characterization and DFT studies of diethyl 4-hydroxy-6-nitro-4H-chromene-2,3-dicarboxylate". Journal of Molecular Structure 1105 (febrero de 2016): 118–27. http://dx.doi.org/10.1016/j.molstruc.2015.10.044.

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47

Azimi, Sara, Omidreza Firuzi, Aida Iraji, Afsaneh Zonouzi, Mahsima Khoshneviszadeh, Mohammad Mahdavi y Najmeh Edraki. "Synthesis and In Vitro Biological Activity Evaluation of Novel Imidazo [2,1-B][1,3,4] Thiadiazole as Anti-Alzheimer Agents". Letters in Drug Design & Discovery 17, n.º 5 (18 de mayo de 2020): 610–17. http://dx.doi.org/10.2174/1570180816666181108115510.

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Background: Considering that AD is multifactorial in nature, novel series of imidazo [2,1-b][1,3,4] thiadiazole derivatives were designed to address the basic factors responsible for the disease. <p> Methods: These compounds were investigated as inhibitors of beta-site APP cleaving enzyme 1, acetylcholinesterase and butyryl cholinesterase. <p> Results: The BACE1 inhibitory results indicated that nitro phenyl substituted derivatives of imidazo [2,1-b][1,3,4] thiadiazole scaffold (R2 = m-NO2) demonstrated superior BACE1 inhibitory activity compared to other substituted moieties. In the BuChE assay, compounds 4h and 4l carrying meta NO2 at R2 of phenyl ring turned out to be potent inhibitors. <p> Conclusion: In conclusion, these novel synthesized derivatives seem to be promising anti-Alzheimer agents.

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48

Inglebert, S. Antony, Jayabal Kamalraja, K. Sethusankar y Paramasivam T. Perumal. "7,7-Dimethyl-2-methylamino-4-(4-methylphenyl)-3-nitro-7,8-dihydro-4H-chromen-5(6H)-one". Acta Crystallographica Section E Structure Reports Online 70, n.º 6 (24 de mayo de 2014): o710—o711. http://dx.doi.org/10.1107/s1600536814010794.

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In the title compound, C19H22N2O4, the six-membered cyclohexenone ring of the chromene unit adopts an envelope conformation, with the dimethyl-substituted C atom as the flap, while the pyran ring has a boat conformation. These two mean planes are inclined to one another by 6.65 (13)°·The benzene ring is normal to the 4H-chromene moiety mean plane, making a dihedral angle of 89.18 (5)°. The methylamine and nitro groups are slightly twisted from the chromene moiety mean plane, with torsion angles C—N—C—O = 1.70 (18) and O—N—C—C = 0.15 (18)°. The molecular structure is characterized by an intramolecular N—H...O hydrogen bond, which generates anS(6) ring motif. In the crystal, molecules are linkedviapairs of weak C—H...O hydrogen bonds, forming inversion dimers. These dimers are connected by further C—H...O hydrogen bonds, forming sheets lying parallel to (10-1).

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49

Govindaraj, J., Y. AaminaNaaz, Jayabal Kamalraja, Paramasivam T. Perumal y A. SubbiahPandi. "Crystal structure of 2-methylamino-3-nitro-4-p-tolylpyrano[3,2-c]chromen-5(4H)-one". Acta Crystallographica Section E Crystallographic Communications 71, n.º 3 (7 de febrero de 2015): o158—o159. http://dx.doi.org/10.1107/s205698901500225x.

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In the racemic title compound, C20H16N2O5, the pyran ring adopts a shallow envelope conformation, with the stereogenic C atom displaced from the other atoms by 0.273 (2) Å. The dihedral angle between the fused-ring system and the pendantp-tolyl group is 87.62 (7)°. The molecular conformation is consolidated by an intramolecular N—H...O hydrogen bond, which generates anS(6) ring. In the crystal, molecules are linked by C—H...O interactions, resulting in [010] chains.

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50

Kolesnik, Irina А., Sergey K. Petkevich, Peter V. Kurman, Alexander S. Lyakhov, Ludmila S. Ivashkevich, Hongwei Zhou y Vladimir I. Potkin. "Synthesis and Structure of 2-Arylamino-Substituted 4-(Dichloromethylidene)-3-Nitro-4h-Pyrido[1,2-a]Pyrimidines". Chemistry of Heterocyclic Compounds 56, n.º 9 (septiembre de 2020): 1187–92. http://dx.doi.org/10.1007/s10593-020-02796-0.

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