G. Vilkauskaitė, A. Šačkus, W. Holzer
Sep 1, 2011
Citations
0
Influential Citations
21
Citations
Journal
European Journal of Organic Chemistry
Abstract
The easily obtainable 5-chloro-1-phenyl-1H-pyrazole-4-carbaldehydes 2 were used as precursors in Sonogashira-type cross-coupling reactions with various alkynes to provide the corresponding 5-alkynyl-1H-pyrazole-4-carbaldehydes 3. Treatment of these with tert-butylamine with microwave assistance afforded the corresponding 1-phenylpyrazolo[4,3-c]pyridines 4. The oximes 5 – derived from the aldehydes 3 – were transformed into the corresponding 1-phenylpyrazolo[4,3-c]pyridine 5-oxides 6 through silver-triflate-catalysed regioselective cyclisation. Ring closure of the oximes 5 in the presence of iodine in ethanol gave the 7-iodo-1-phenylpyrazolo[4,3-c]pyridine 5-oxides 7. Detailed NMR spectroscopic investigations were undertaken with all obtained products.