1257403-89-6Relevant academic research and scientific papers
Synthesis of 6-alkyl-7-oxo-4,5,6,7-tetrahydropyrazolo[1,5-c]pyri-midine-3-carboxamides
Lombar, Klara,Groelj, Uro,Dahmann, Georg,Stanovnik, Branko,Svete, Jurij
, p. 497 - 506 (2015/02/19)
Two variants of the synthesis of 6-alkyl-7-oxo-4,5,6,7-tetrahydropyrazolo[1,5-c]pyrimidine-3-carboxamides have been developed. The first pathway comprises nine steps starting with the introduction of the 6-alkyl group (R1) via addition of a primary alkylamine to methyl acrylate followed by a seven-step transformation into the 6-benzyl-7-oxo-4,5,6,7-tetrahydropyrazolo[1,5-c]pyrimidine-3-carboxylic acid, which is then amidated into title compounds. The other variation is based on an analogous four-step transformation of Boc-β-alanine into a 6-unsubstituted benzyl ester as the key intermediate. The 6-alkyl group (R1) is then introduced by N-alkylation with alkyl halides, followed by O-debenzylation to give the carboxylic acids, and amidation. A library of 18 title carboxamides was prepared in very good yields.
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.
