title: Synthesis and antimicrobial evaluation of new 1,4-dihydro-4-pyrazolylpyridines and 4-pyrazolylpyridines.
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.
authors.affiliation: Department of Chemistry, Dyal Singh College, Karnal 132 001, India. ravi.dhamija@rediffmail.com.
authors.forename: Om
authors.initials: O
authors.lastname: Prakash
authors.forename: Khalid
authors.initials: K
authors.lastname: Hussain
authors.forename: Ravi
authors.initials: R
authors.lastname: Kumar
authors.forename: Deepak
authors.initials: D
authors.lastname: Wadhwa
authors.forename: Chetan
authors.initials: C
authors.lastname: Sharma
authors.forename: Kamal R
authors.initials: KR
authors.lastname: Aneja