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A facile and novel synthesis of 5‐phenylimidazo[4,5‐ c ][1,8]naphthyridin‐4(5 H )‐ones
Author(s) -
Kuroda Takeshi,
Suzuki Fumio
Publication year - 1991
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.5570280840
Subject(s) - chemistry , regioselectivity , imidazole , moiety , ethyl chloroformate , medicinal chemistry , stereochemistry , benzimidazole , combinatorial chemistry , organic chemistry , catalysis
A convenient and regioselective synthesis of a new heterocycle, 5‐phenyl‐1 H or 3 H ‐imidazo[4,5‐c][1,8]‐naphthyridin‐4(5 H )‐one 1‐a or 1‐b , is described. Methyl 2‐anilinonicotinate 15 was transformed into the valuable intermediate, N ‐phenyl‐3‐azaisatoic anhydride 4 using trichloromethyl chloroformate (TCF). Treatment of 4 with the anion of ethyl nitroacetate gave 4‐hydroxy‐3‐nitro‐1‐phenyl‐1,8‐naphthyridin‐4(5 H )‐one 3 . Compound 3 was chlorinated, aminated, reduced, and cyclized to afford 5‐phenylimidazo[4,5‐ c ][1,8]naphthyridin‐4(5 H )‐one 1 . Regioselective substitution at the 1 or 3‐position in the imidazole moiety of 1 was achieved by minor changes of the above scheme.