1257403-90-9Relevant academic research and scientific papers
Synthesis of 1,5,6,7-tetrahydro-4H-pyrazolo[4,3-c]pyridin-4-ones as conformationally constrained pyrazole analogues of histamine
Zerovnik, Darja,Groselj, Uros,Kralj, David,Malavasic, Crt,Bezensek, Jure,Dahmann, Georg,Stare, Katarina,Meden, Anton,Stanovnik, Branko,Svete, Jurij
experimental part, p. 3363 - 3373 (2010/11/19)
Three synthetic methods for the preparation of 1,5-disubstituted 1,5,6,7-tetrahydro-4H-pyrazolo[4,3-c]pyridin-4-ones as heterocyclic histamine analogues were developed. The first method starts from easily available methyl 5-(2-aminoethyl)-1H-pyrazole-4-carboxylates, which were N-alkylated and the resulting secondary amines were cyclised in the presence of a base to give the title compounds in 17-92% yields (method A). Alternatively, the amines were first cyclised to the 5-unsubstituted pyrazolo[4,3-c]pyridin-4-ones. Subsequent N-benzylation afforded three of the title compounds in 36-49% yields (method B). The third method comprises a six-step transformation of methyl acrylate into 1-benzylpiperidine-2,4-dione. Treatment of the latter with N,N-dimethylformamide dimethylacetal (DMFDMA) followed by acid-catalysed cyclisation of the formed enaminone with methyl-, phenyl- and tert-butylhydrazine afforded the same three title compounds in 79-87% yields (method C). Georg Thieme Verlag Stuttgart New York.
