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Synthesis and antimicrobial evaluation of new 1,4-dihydro-4-pyrazolylpyridines and 4-pyrazolylpyridines

Om Prakash1, Khalid Hussain2, Ravi Kumar3*, Deepak Wadhwa4, Chetan Sharma5 and Kamal R Aneja5

Author Affiliations

1 Institute of Pharmaceutical Sciences, Kurukshetra University, Kurukshetra 136 119, India

2 Department of Chemistry, Guru Nanak Khalsa College, Yamunanagar 135001, India

3 Department of Chemistry, Dyal Singh College, Karnal 132 001, India

4 Department of Chemistry, Kurukshetra University, Kurukshetra 136 119, India

5 Department of Microbiology, Kurukshetra University, Kurukshetra 136 119, India

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Organic and Medicinal Chemistry Letters 2011, 1:5  doi:10.1186/2191-2858-1-5

Published: 3 August 2011

Abstract

Background

Dialkyl 1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylates (1,4-DHP) have now been recognized as vital drugs. Some of these derivatives such as amlodipine, felodipine, isradipine, etc. have been commercialized. In view of wide range of biological properties associated with 1,4-DHP and owing to the biological importance of the oxidation step of 1,4-DHP, we carried out the synthesis and antimicrobial evaluation of new diethyl 1,4-dihydro-2,6-dimethyl-4-(3-aryl-1-phenyl-4-pyrazolyl)pyridine-3,5-dicarboxylates (2a-g) and diethyl 2,6-dimethyl-4-(3-aryl-1-phenyl-4-pyrazolyl)pyridine-3,5-dicarboxylates (3a-g).

Results

Synthesis of a series of new diethyl 1,4-dihydro-2,6-dimethyl-4-(3-aryl-1-phenyl-4-pyrazolyl)pyridine-3,5-dicarboxylates (2a-g) has been accomplished by multicomponent cyclocondensation reaction of ethyl acetoacetate, 3-aryl-1-phenyl pyrazole-4-carboxaldehyde (1a-g) and ammonium acetate. The dihydropyridines 2a-g were smoothly converted to new diethyl 2,6-dimethyl-4-(3-aryl-1-phenyl-4-pyrazolyl)pyridine-3,5-dicarboxylates (3a-g) using HTIB ([Hydroxy (tosyloxy)iodo]benzene, Koser's reagent) as the oxidizing agent. The antimicrobial studies of the title compounds, 2a-g & 3a-g, are also described.

Keywords:
1,4-Dihydro-4-pyrazolylpyridines; 4-pyrazolylpyridines; HTIB; oxidation; antibacterial activity; antifungal activity

Graphical abstract