Background:
In this study, an efficient synthesis of novel bispyrazole heterocyclic molecules by condensation of substituted
aromatic aldehydes with 1,3-diketo-N-phenylpyrazole by using Mg/Al-LDH as heterogeneous catalyst is reported. The attractive features of
this protocol are as follows: mild reaction conditions, good yields and easiness of the catalyst separation from the reaction mixture. Further,
a mechanistic study has been performed by using DFT calculations to explain the observed selectivity of the condensation reaction between
aryl aldehyde and 1,3-diketo-N-phenylpyrazole via Knoevenagel reaction. The local electrophilicity/ nucleophilicity that allows explaining
correctly the experimental finding.
Methods:
The bispyrazole derivatives 3a-m were prepared by condensation reaction of substituted aromatic aldehydes with 1,3-diketo-Nphenylpyrazole by using Mg/Al-LDH as heterogeneous catalyst under THF solvent at the refluxing temperature.
Objective:
To synthesize a novel bispyrazole heterocyclic molecule may be have important biological activities and thus can be good
candidates for pharmaceutical applications.
Results:
This protocol describes the Synthesis of Bioactive Compounds under mild reaction conditions, good yields and easiness of the
catalyst separation from the reaction mixture. Further, a mechanistic study has been performed by using DFT calculations to explain the
observed selectivity of the condensation reaction between aryl aldehyde and 1,3-diketo-N-phenylpyrazole via Knoevenagel reaction. The
local electrophilicity/ nucleophilicity that allows explaining correctly the experimental finding.
Conclusion:
In summary, the pharmacologically interesting bis-pyrazole derivatives have been synthesized through Mg/Al-LDH as a solid base
catalyst, in THF as solvent. Thus, the synthesized bioactive compounds containing the pyrazole ring may be have important biological activities
and thus can be good candidates for pharmaceutical applications. Therefore, the catalyst Mg/Al-LDH showed high catalytic activity. Besides, a
series of bispyrazole molecules were synthesized with a good yield and easy separation of the catalyst by simple filtration. Moreover, DFT
calculations and reactivity indexes are used to explain the selectivity of the condensation reaction between aryl benzaldehyde and 1,3-diketo-Nphenylpyrazole via Knoevenagel reaction, and the results are in good agreement with the experimental finding.
Green condensation reaction of aromatic aldehydes with active methylene compounds catalyzed by anion-exchange resin under ultrasound irradiation
