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Studies on quinoline derivatives and related compounds. 1. A new synthesis of 1‐alkyl‐1,4‐dihydro‐4‐oxo‐3‐quinolinecarboxylic acids
Author(s) -
Agui Hideo,
Mitani Toru,
Nakashita Mitsuo,
Nakagome Takenari
Publication year - 1971
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.5570080302
Subject(s) - chemistry , alkyl , acetic anhydride , hydrolysis , quinoline , organic chemistry , fluoride , sulfuric acid , phosphorus , acetic acid , medicinal chemistry , catalysis , inorganic chemistry
Abstract A novel preparative method for 1‐alkyl‐1,4‐dihydro‐4‐oxo‐3‐quinolinecarboxylic acids was developed. The key process is the cyclization of N ‐alkylanilinomethylenemalonales, which was effected successfully in the presence of polyphosphoric acid, polyphosphate ester, boron tri‐fluoride or a mixture of acetic anhydride and sulfuric acid. With phosphorus oxychloride, N ‐alkylanilinomethylenemalonates yielded 1‐alkyl‐4‐chloro‐3‐carbethoxyquinolinium salts which were hydrolyzed readily to ethyl 1‐alkyl‐1,4‐dihydro‐4‐oxo‐3‐quinolineearboxylates or their acids. By means of this novel method several new 1‐alkyl‐1,4‐dihydro‐4‐oxo‐3‐quinolineearboxylic acids were prepared.