- Simple access toward 3-halo- and 3-nitro-pyrazolo[1,5-a] pyrimidines through a one-pot sequence
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Herein, a regioselective, time-efficient and one-pot route for the synthesis of diversely substituted 3-halo- and 3-nitropyrazolo[1,5-a]pyrimidines in good to excellent yields through a microwave-assisted process is provided. The reaction features a sequential cyclocondensation reaction of β-enaminones with NH-5-aminopyrazoles, followed by a regioselective electrophilic substitution with easily available electrophilic reagents. This methodology is distinguished by its short reaction times, high-yield, operational simplicity, broad substrate scope and pot-economy. Furthermore, these 3-functionalized heterocycles have been successfully used in the synthesis of 3-alkynyl and 3-aminopyrazolo[1,5-a]pyrimidines in yields up to 92%.
- Castillo, Juan-Carlos,Rosero, Hernán-Alejandro,Portilla, Jaime
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p. 28483 - 28488
(2017/07/07)
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- C-C recyclizations of some 2,7-disubstituted 6-ethoxycarbonylpyrazolo[1,5- a]pyrimidines
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Condensation of ethyl ethoxymethyleneacetoacetate and ethyl ethoxymethylenecyanoacetate in ethanol with 3-substituted 3-aminopyrazoles and 5-amino-1,2,4-triazole gave the 2-substituted 6-ethoxy- carbonyl-7-methyl- and 7-amino-6-ethoxycarbonylpyrazolo[1,5-
- Danagulyan,Boyakhchyan,Danagulyan,Panosyan
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experimental part
p. 321 - 331
(2011/12/15)
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- Reactivity of 7-(2-Dimethylaminovinyl)pyrazolopyrimidines: Synthesis of Pyrazolopyridopyrimidine Derivatives as Potential Benzodiazepine Receptor Ligands. 2.
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A series of pyrazolopyridopyrimidin-6-ones was obtained by reaction of ammonium acetate with ethyl 7-dimethylaminovinylpyrazolopyrimidine-6-carboxylates and these had been prepared from ethyl 7-methylpyrazolopyrimidine-6-carboxylates by reaction with dimethylformamide dimethylacetat.Under these conditions the compounds bearing a 2-hydroxy group were also O-alkylated.During the preparation of the ethyl 2-hydroxy-7-methyl-3-phenylpyrazolopyrimidine-6-carboxylate the corresponding 5-methyl isomer was isolated and identified.
- Bruni, Fabrizio,Selleri, Silvia,Costanzo, Annarella,Guerrini, Gabriella,Casilli, Maria Lucia,Giusti, Laura
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p. 291 - 298
(2007/10/02)
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