Theme-Others
Reactions of Some Pyrazole Derivatives
Dilek Demir 1, Behzat Altural 2
1
Anadolu University, Faculty of Engineering, Department of Chemical Engineering, 26480, Eskişehir,
Turkiye
2
Erciyes University, Science Faculty, Department of Chemistry, 38039, Kayseri, Turkiye
Presenting Author: d_demir@anadolu.edu.tr
Introduction
Pyrazole systems have found considerable attention in chemical and pharmaceutical industries and also
in literature as they possess a wide range of biological activities such as antibacterial, anticancer and
antifungal activities and these pharmacological activities have inspired chemists to synthesize
substituted pyrazole systems in order to explore the usefulness of this heterocyclic template. Here we
report the reduction reactions of carbohydrazide moieties 2a-c with NaBH4 to obtain alcohol derivatives
of carbohydrazides (3a-c), as well as reactions of 1 with 1,3-dicarbonyl derivatives by Claisen
condensation to obtain 5 a-d (Figure 1). Structures of all compounds were identified by spectroscopic
and elemental analysis.
Materials and Method
Solvents and all other chemical reagents were purchased from Merck, Sigma and Fluka and used without
further purification. TLC: DC Alufolien Kieselgel 60 / F254 Merck TLC plates, Camag lamp (254/366
nm). Melting points: Electrothermal 9200 melting point apparatus, uncorrected. Microanalyses: Leco932 CHNS-O analyser. IR spectra: Shimadzu FTIR-8400 spectrophotometer in cm-1. 1H-and 13C-NMR
spectra: Bruker 200 MHz and Bruker Avance III 400 MHz spectrometers δ in ppm, J in Hz.
Results and Discussion
Compounds 2a-c were synthesized from 4-benzoyl-5-phenyl-1-aryl-1H-pyrazole-3-carboxylic acid
chloride (1) with hydrazide derivatives by substitution reactions. Compounds 3a-c were synthesized by
the reduction reaction of the carbohydrazide compounds (2a-c) with NaBH4 in THF medium.
O
O
Ph
Ph
Cl
N
N
Ph
1
O
O
R1 NH NH2
NH NH
Ph
Ph
O
O
OH
R1
NaBH 4
N
N
Ph
2 a-c
THF
R1
NH NH
Ph
Ph
O
O
R1
N
N
Ph
3 a-c
3a -Ph
3b -CH 2-Ph
3c -CH 3
Figure 1. Synhtesis of 3a-c
Compounds 4a-d were synthesized from 4-benzoyl-5-phenyl-1-aryl-1H-pyrazole-3-carboxylic acid
chloride (1) with 1,3-dions by Claisen condensations.
O
O
Ph
Ph
O
Cl
R2
O
O
R2
N
Ph
1
R2
4a
4b
4c
4d
-C(CH 3)3
-Ph
-Ph-CH 3 (p)
-Ph-OCH 3 (p)
O
Ph
Ph
N
O
N
O
R2
R2
N
Ph
4 a-d
Figure 2. Synhtesis of 4a-d
This article reported facile synthesis of new alcohol derivatives of carbohydrazides 3a-c from the
reduction reactions of carbohydrazide structure (2a-c) and triketo structures (4a-d) from pyrazole
skeleton 1. All the products were easily purified and obtained with good yield and characterized by
spectroscopic techniques. As compounds including these moieties possess biological activities, these
compounds would deserve further investigations in medicinal and biosynthetic chemistry.