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A convenient route for the synthesis of pyrazolo[3,4‐ d ]pyrimidine, pyrazolo[3,4‐ b ][1,6]naphthyridine and pyrazolo[3,4‐ b ]quinoline derivatives
Author(s) -
Jachak Madhukar N.,
Avhale Appasaheb B.,
Medhane Vijay J.,
Toche Raghunath B.
Publication year - 2006
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570430506
Subject(s) - chemistry , acetonitriles , cyclohexanone , quinoline , formylation , phenanthridine , hydrazine (antidepressant) , cyclopentanone , dimedone , medicinal chemistry , annulation , pyrimidine , tetralone , formamide , dehydrogenation , stereochemistry , organic chemistry , catalysis , chromatography , acetonitrile
Friedländer condensation of 5‐aminopyrazole‐4‐carbaldehydes 1 with formamide 2a or benzamide 2b gave pyrazolo[3,4‐ d ]pyrimidine derivatives 3 . Cyclocondensation of 1 with cyclopentanone, N ‐benzyl‐4‐piperidone and 6‐methoxy‐1‐tetralone yielded cyclopenta[ b ]pyrazolo[4,3‐ e ]pyridines 4 , pyrazolo[3,4‐ b ]‐[1,6]naphthyridines 5 and benzo[ h ]pyrazolo[3,4‐ b ]quinolines 6 , respectively. Analogous condensation of cyclohexanone 7a or 2‐methyl‐1‐cyclohexanone 7b with 1 afforded pyrazolo[3,4‐ b ]quinoline derivatives 8a‐d . Heating 1 with dimedone furnished pyrazolo[3,4‐ b ]quinolinone derivatives 9 . Vilsmeier‐Haack formylation of 9 yielded a mixture of two compounds 10 and 11 . Further bispyrazolo[3,4‐ b :4,3‐ f ]‐quinolines 12a, b were obtained on cyclocondensation of 11a, b with phenyl hydrazine.