Meso-ionic heterocycles (1976–1980)

Newton, Christopher G.; Ramsden, Christopher A.

doi:10.1016/0040-4020(82)80186-5

Cited by 293 publications

(82 citation statements)

References 236 publications

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“…They possess a betaine-like character with a partial positive charge on the heterocyclic ring that is balanced by a negative charge located on an exocyclic atom or group. 1,2 The large separation between the charged regions leads to large dipole moments of about 4-5 D. 3,4 These properties suggest the possibility of interacting with biomolecules such as proteins and DNA. Additionally, the overall neutral character of these compounds enables them to cross biological membranes.…”

Section: Introductionmentioning

confidence: 99%

Improved synthesis of 1,3,4-thiadiazolium-2-phenylamines using microwave and ultrasound irradiation and investigation of their cytotoxic activity

Reis¹,

Echevarria-Lima²,

Miranda³

et al. 2011

J. Braz. Chem. Soc.

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Uma nova e eficiente síntese de oito derivados da classe 1,3,4-tiadiazolio-2-fenilaminas (1-8, sendo o derivado 8 inédito na literatura) foi realizada utilizando cloreto de tionila ou cloreto de trimetilsilano como catalisadores sob irradiação de microondas ou ultra-som. Os compostos alvos foram obtidos em bons rendimentos e em tempo extraordinariamente curtos, 5 min sob irradiação de microondas e 10 min sob irradiação de ultra-som, quando comparados com a metodologia tradicional (24 a 48 h em repouso a temperatura ambiente). Os melhores rendimentos foram obtidos usando irradiação de microondas e, de maneira geral, usando o cloreto de tionila ao invés de cloreto de trimetilsilano. A citotoxicidade foi avaliada frente à linhagem de leucemia humana K562 e do linfoma Daudi, apresentando resultados promissores para o derivado cloreto de 4-fenil-5-(4'-nitro-estiril)-1,3,4-tiadiazolio-2-fenilamina.A new and efficient synthesis of eight 1,3,4-thiadiazolium-2-phenylamine derivatives (1-8, where 8 is novel in the literature) was performed using thionyl chloride or trimethylsilyl chloride as catalysts under microwave or ultrasound irradiation. The target compounds were obtained in good yields and remarkably short times, 5 min under microwave irradiation and 10 min under ultrasound irradiation, where compared to traditional methodology (24 to 48 h at room temperature standing). The best yields were obtained using the microwave irradiation and, in general way, using thionyl chloride instead trimethylsilyl chloride. The cytotoxicity against K562 human leukemia and Daudi lymphoma lines was evaluated and showed promising results from the 4-phenyl-5-(4'-nitro-styryl)-1,3,4-thiadiazolium-2-phenylamine chloride derivative.Keywords: mesoionic heterocycle compounds, microwave, ultrasound, cytotoxic activity IntroductionMesoionic compounds are a special class of heterocycles with potential therapeutic applications due to their unique chemical properties. They possess a betaine-like character with a partial positive charge on the heterocyclic ring that is balanced by a negative charge located on an exocyclic atom or group.1,2 The large separation between the charged regions leads to large dipole moments of about 4-5 D.3,4 These properties suggest the possibility of interacting with biomolecules such as proteins and DNA. Additionally, the overall neutral character of these compounds enables them to cross biological membranes. Different classes of mesoionic compounds have demonstrated a wide range of biological activities such as anti-inflammatory and analgesic, 5 antiparasitic, 6,7 antibacterial, 8,9 antiplatelet, fibrinolytic, thrombolytic and broncholytic effects, 10 as well as anticancer potency.11-17 The promising therapeutic applications have led us to study these interesting compounds in our laboratory. We have previously described the survival enhancement of Ehrlich and Sarcoma 180 tumor-bearing mice treated with 4-phenyl-5-(4'-X-styryl)-1,3,5-thiadiazolium-2-phenylamine chlorides.12 Respiratory chain inhibition, transmembrane ...

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Section: Introductionmentioning

confidence: 99%

Improved synthesis of 1,3,4-thiadiazolium-2-phenylamines using microwave and ultrasound irradiation and investigation of their cytotoxic activity

Reis¹,

Echevarria-Lima²,

Miranda³

et al. 2011

J. Braz. Chem. Soc.

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“…Após intervalos de tempo convenientes para cada reação (1 hora e 30 minutos 1a + 2; 3 horas 1b + 2 e 5 horas 1c + 2), em repouso, adicionou-se ao meio de reação CH 2 Cl 2 (30 mL) e em seguida HCl concentrado (2 mL) a 0 o C. A fase orgânica foi separada imediatamente e tratada com HCl 1N (10 mL); água (2 mL); solução de NaCl saturada (20 mL) e Na 2 SO 4 anidro. Os cristais obtidos em cada reação foram cromatografados em coluna de silica gel usando CHCl 3 Compostos 4 -Os compostos 4a-c foram obtidos a partir das reações descritas para a obtenção de 3a-c em condições úmidas, sendo isolados por cromatografia em coluna da mistura com seus isomeros 5a-c. Os referidos compostos também foram obtidos a partir dos cloretos de ácido correspondentes (42 mmoles) em 1,4-dioxano (20 mL) seco, adicionados sob agitação, a suspensões de 1,4-difeniltiossemicarbazida e 1,4-dioxano (20 mL). As misturas de reação foram deixadas em repouso, em sistema fechado isento de umidade.…”

Section: Parte Experimentalunclassified

“…Compostos heterocíclicos mesoiônicos da série dos 1,3,4-tiadiazólio-2-aminidas e seus isômeros 1,3,4-triazólio-2-tiolatos têm sido sintetizados a partir das reações de acilação anidra de tiossemicarbazidas substituídas [1][2][3] . O estudo dessas reações levou, desde 1957, a controvérsias quanto aos produtos obtidos, 4,5 sendo recentemente comprovado por estudos de RMN de 1 H, 13 C, 15 N e difração de Raios-X que, dependendo das condições reacionais podem ser obtidos diretamente da acilação anidra derivados do sistema 1,3,4-tiadiazólio-2-aminida [6][7][8][9] .…”

Section: Introductionunclassified

Isolamento e caracterização de acil-tiossemicarbazidas como intermediários na síntese de compostos mesoiônicos

Maciel¹,

Echevarrı́a²,

Rumjanek³

1998

Quím. Nova

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“…Mesoionic azolopyridines of the general formula I are related to the family of condensed munchnones [1].…”

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confidence: 99%

Fused munchnones in recyclization tandems

Бабаев

2000

Journal of Heterocyclic Chem

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Mesoionic azolopyridines of the general formula I are related to the family of condensed munchnones [1].Although the chemistry of b-fused oxazolones la [2] and imidazopyridine derivatives Ib [3] is well reviewed, no data are reported yet about the synthesis of the mesoionic thiazolopyridines Ic-e. In the first part of this review we discuss novel strategy to the synthesis of condensed thiazoles Ic-e and describe structural features of munchnones la and Ic for which we report X-ray data for the first time. In the second part we introduce the concept of recyclization tandems: Mesoionic system la may be easily transformed to highly reactive oxazolo[3,2-a]pyridinium cation which, in turn, undergoes variety of ring opening/transformation reactions leading to novel classes and subclasses of heterocyclic compounds. Synthesis of Novel b-Fused Munchnones.Krohnke first attempted to prepare mesoionic thiazoles Ic by cycloaddition of carbon disulfide to pyridinium and isoquinolinium ylides [4]. Although in the case of isoquinolines IIa the desired mesoionic product IIIa was obtained, the reaction of pyridinium salt IIb led only to the stabilized compound IIlb and not to the parent munchnone.This result can be clearly explained in terms of higher electron deficiency of the isoquinolinium than that of the pyridinium ring. The presence of a leaving group at a-position of the initial pyridinium salt would favor cyclization. We found that 2-chloropyridinium salts IVa,b in reaction with carbon disulfide at room temperature form the desired mesoionic thiazolopyridines Va,b [5]. Structure of the compound Va was confirmed by X-ray analysis.Analogous reaction between carbon oxosulfide and the salt IVa led to another mesoionic system VI; the yield, however, was low (<10%), and we performed a multistep synthesis of compound VI starting from the available 2-bromopyridinium salt VII [6].

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Meso-ionic heterocycles (1976–1980)

Cited by 293 publications

References 236 publications

Improved synthesis of 1,3,4-thiadiazolium-2-phenylamines using microwave and ultrasound irradiation and investigation of their cytotoxic activity

Improved synthesis of 1,3,4-thiadiazolium-2-phenylamines using microwave and ultrasound irradiation and investigation of their cytotoxic activity

Isolamento e caracterização de acil-tiossemicarbazidas como intermediários na síntese de compostos mesoiônicos

Fused munchnones in recyclization tandems

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