Methods for the synthesis of 4-pyrazolyl- and 4pyridyl-5-oxo-1, 4,5,7-tetrahydrofuro[3,4-b]pyridines

The most suitable method for the synthesis of 4-pyrazolyl- or 4-pyridyl-5-oxo-1, 4, 5, 7-tetrahydrofuro[3, 4b]pyridines uses 4-chloro- or 4-acetoxyacetoacetic esters in various versions of the Hantsch synthesis with closure of a lactone ring during the reaction. Some of the intermediate products (2-chloromethyl- and 2acetoxymethyl-1,4-dihydropyridines) were isolated. Cyclization with the formation of lactones does not occur in N-substituted 1, 4-dihydropyridines.Latvian Institute of Organic Synthesis, Riga. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 966–972, July, 1995. Original article submitted May 24, 1995.