A Convenient Method to Obtain 4,5-Dihydro-<i>1H</i>-Methylpyrazoles by A Ring Transformation Reaction
作者:Helio Gauze Bonacorso、Arci Dirceu Wastowski、Nilo Zanatta、Marcos Antonio Pinto Martins
DOI:10.1080/00397910008087174
日期:2000.4
Abstract A convenientmethod for the synthesis of alkyl[aryl]-substituted 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-methylpyrazole (2) from a new ring transformation reaction of alkyl[aryl]-substituted-5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-1-pyrazolethiocarboxyamide (1) with methylhydrazine in THF, and the thermal dehydration of 2, are reported.
Haloacetylated enol ethers 10. Condensation of β-alkoxyvinyl trifluoromethyl ketones with thiosemicarbazide. Synthesis of new trifluoromethyl 4,5-dihydro-1H-1-pyrazolethiocarboxyamides
thiocarboxyamides (2a–g) from the direct cyclo-condensation reaction of β-alkoxyvinyltrifluoromethylketones (1a–g) with thiosemicarbazide in methanol, under mild conditions, is reported. Similarly, the 1H-1-pyrazolethiocarboxyamide derivatives (2a–g) were easily dehydrated and the thiocarboxyamide group hydrolyzed in a one-step reaction by stirring with concentrated sulfuric acid to give the 3-a
3-芳基的合成[烷基] -5-羟基-5-三氟甲基-4,5-二氢ħ -1- pyrazolethiocarboxyamides(2A-G从β-烷氧基乙烯基三氟甲基酮的直接环缩合反应)(1A报道了在温和条件下用硫代氨基脲在甲醇中生成–g)。同样,1 H -1-吡唑硫代羧酰胺衍生物(2a–g)易于脱水,硫代羧酰胺基团通过与浓硫酸搅拌一步反应水解,得到3-芳基[烷基] -5-三氟甲基-1 H-吡唑类(3a–g)收率高。3-芳基[烷基] -5-羟基-5-三氟甲基-4,5-二氢-1 H的特定合成和物理性质此处首次报道了-1-吡唑硫代羧酰胺。