Ratio of 1,3- and 1,5-dialkyl-substituted pyrazoles obtained from chlorovinyl alkyl ketones and alkylhydrazines, 3(5)-pyrazoles and alkyl bromides

Abstract

Unsymmetrically substituted 1,3-and 1,5-dialkylpyrazoles and 1,3-dialkyl-5-chloropyrazoles were prepared. 2-Chlorovinyl ketones react with С 1 -С 8 -alkylhydrazines along two routes giving mixtures of 1-R'-3-R-and 1-R'-5-R-pyrazoles with the prevalence of 1,3-isomer. The proportion of 3-substituted 1-alkylpyrazole in the isomers mixture grows from 60 to 94-97% with growing length of the alkyl chain in the hydrazine. The alkylation of 1-unsubstituted 3(5)-alkylpyrazoles with alkyl bromides afforded predominantly (by 16-50%) 1,3-disubstituted pyrazoles. 1,3-Dialkyl-5-chloropyrazoles form from 2,2-dichlorovinyl alkyl ketones and functionalized alkylhydrazines. It was suggested to synthesize 1,3-dialkyl-substituted pyrazoles by dechlorination of unsymmetrically substituted 1,3-dialkyl-5-chloropyrazoles in the presence of complex nickel catalyst and water as the proton source.

A Copper–Nitroxide Adduct Exhibiting Separate Single Crystal-to-Single Crystal Polymerization–Depolymerization and Spin Crossover Transitions

“…The mass spectrum was recorded on a DFS (Thermo Electron) high-resolution mass spectrometer. The synthesis of 1-methyl-3-ethyl-1 H -pyrazole and a mixture of 1-butyl-3(5)-ethyl-1 H -pyrazoles was described elsewhere, , respectively. 4-Formylpyrazoles were prepared by the procedure reported elsewhere …”

6aH‐Benzo[α]fluorene: NMR evidence of the unexpected product of the reaction of butyryl chloride with 1,2‐diphenylacetylene

“…It has been previously shown that the reaction of butyryl chloride with ethyne in CH 2 Cl 2 in the presence of AlCl 3 as a catalyst affords 1‐chlorohex‐1‐en‐3‐one 1 in 66% yield (Scheme 1). 34 …”

“…It has been previously shown that the reaction of butyryl chloride with ethyne in CH 2 Cl 2 in the presence of AlCl 3 as a catalyst affords 1-chlorohex-1-en-3-one 1 in 66% yield (Scheme 1). 34 In this work, we carried out the reaction of butyryl chloride with ethynylbenzene under the same conditions. The expected 1-chloro-1-phenylhex-1-en-3-one 2 was obtained as a mixture of the Z/E isomers in a ratio of 10/1 in 71% yield.…”

The Structure of Biologically Active Functionalized Azoles: NMR Spectroscopy and Quantum Chemistry

“…The known methods for obtaining these practically important substances are complex and multi-stage, while the yields of the final products are low [100,101]. As a result of the search for new ways of recycling rocket fuel, as mentioned above, we have proposed an original method for the formation of functionally substituted pyrazoles or isoxazoles using heptyl (or hydroxylamine) or other reagents [102][103][104][105][106][107][108][109][110][111][112].…”