Síntese e reações de 5-trifluormetil- 4,5-diidro-1H-1-pirazoltiocarboxamida 3(4)-substituídos
This thesis describes the synthesis and application as bi-heterocyclic precursor a series of 3-aryl[alkyl]-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1- pyrazolethiocarboxamides (2), which are easily obtained from the direct cyclocondensation reaction of β-alkoxyvinyl trifluoromethyl ketones (1) wit...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2002 |
| País: | Brasil |
| Institución: | Universidade Federal de Santa Maria (UFSM) |
| Repositorio: | Manancial - Repositório Digital da UFSM |
| Idioma: | portugués |
| OAI Identifier: | oai:repositorio.ufsm.br:1/27118 |
| Acceso en línea: | http://repositorio.ufsm.br/handle/1/27118 |
| Access Level: | acceso abierto |
| Palabra clave: | Cetonas trifluormetiladas Pirazóis 4,5-diidro-1H-pirazóis Trifluormetil pirazóis Tiazóis Pirazolil-tiazol CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA |
| Sumario: | This thesis describes the synthesis and application as bi-heterocyclic precursor a series of 3-aryl[alkyl]-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1- pyrazolethiocarboxamides (2), which are easily obtained from the direct cyclocondensation reaction of β-alkoxyvinyl trifluoromethyl ketones (1) with thiosemicarbazide in methanol, under mild conditions (r.t - 450C, 20-24 h) and in good yields (73-96%). Similarly, the 1H-1-pyrazolethiocarboxamide derivatives (2) were dehydrated and the thiocarboxamide group hydrolyzed in an one-step reaction by stirring with concentrated sulfuric acid under reflux for 4 hours to give the 3-aryl[alkyl]-5- trifluoromethyl-1H-pyrazoles (3) in good yield (57-75%). In a subsequent application reaction of 3-aryl[alkyl]-5-hydroxy-5-trifluoromethyl- 4,5-dihydro-1H-1-pyrazolethiocarboxamides (2), the synthesis of alkyl[aryl]-substituted 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-methylpyrazoles (4) in good yields (68- 90%) from a new ring transformation reaction of alkyl[aryl]-substituted-5-hydroxy-5- trifluoromethyl-4,5-dihydro-1H-1-pyrazolethiocarboxyamides (2) with methylhydrazine in THF (2-7 hours a 20-250C), is reported. The thermal dehydration reaction of these pyrazolines (4) furnished the respective N-methylpyrazoles (5). Finally, a convenient method for the synthesis of a novel series of eighteen noncondensed 5,5-bicycles, specifically 2-(3-alkyl(phenyl)-5-hydroxy-5-trifluoromethyl-4,5- dihydro-1H-pyrazol-1-yl)-4-phenyl-5-alkyl-thiazoles and -4,5,6,7- tetrahydrobenzothiazoles (6), in good yields (57-98%), from the reaction of 3-alkyl(phenyl)-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-pyrazolethiocarboxamide (2) with 2-bromoacetophenone, 2-bromopropiophenone and 2-bromocyclohexanone, is reported. The dehydration of these compounds by stirring at reflux for 5 hours with a mixture of concentrated sulfuric acid/acetic acid 1:10 v/v, led to the corresponding 2-[3- alky(phenyl)-5-trifluoromethyl-1H-pyrazol-1-yl]-4-phenyl-5-alkylthiazoles and respective -4,5,6,7-tetrahydrobenzothiazoles (7) in good yield (75-93%). |
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