Preparation of lithium 5-lithiomethyl-3-methylpyrazole-1-carboxylate and its reaction with α-oxoketene dithioacetals: A new general method for substituted and annelated pyrazolo[1,5-a]pyridines

Article abstract of DOI:10.1016/S0040-4020(99)00380-4

5-Methylpyrazole derivative 1 is metallated at the C-5 methyl carbon atom to form lithium 5-lithiomethyl-3-methylpyrazole-1-carboxylate 3 which on reaction with α-oxoketene dithioacetals 4a-d, 12a-c and 15a-b yields substituted and annelated pyrazolo[1,5-