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The reactions of some ortho ‐substituted anilines with various α,β‐acetylenic ketones. A route to substituted quinolines
Author(s) -
Sinsky M. S.,
Bass R. G.
Publication year - 1984
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.5570210325
Subject(s) - chemistry , tautomer , acetylene , quinoline , medicinal chemistry , enamine , sodium methoxide , organic chemistry , aryl , alkyl , catalysis
The reactions of some ortho ‐substituted anilines with various α,β‐acetylenic ketones were investigated as a route to 4‐alkyl‐, 4‐aryl‐, 4‐hydroxy‐, and 4‐amino‐3‐quinolyl ketones. The anilines examined were 2‐aminoacetophenone ( 1 ), 2‐aminobenzophenone ( 2 ), anthranilonitrile ( 3 ), methyl anthranilate ( 4 ), and ethyl anthranilate ( 5 ). The acetylenic ketones used were 1,4‐diphenyl‐2‐butyne‐1,4‐dione ( 6 ), 3‐butyn‐2‐one (7), 1,3‐diphenyl‐2‐propyn‐1‐one ( 8 ), and 4‐phenyl‐3‐butyn‐2‐one ( 9 ). The acetylenic ketones typically reacted with the anilines to give enamines; however, exceptions were found. Acetylene 6 reacts with 3 to give the enamine ( 13 ) along with a small amount of 2,3‐dibenzoyl‐4‐quinolamine ( 14 ). The reactions of 1 or 2 with 6 give the respective quinoline derivatives directly. Acetylene 8 reacts with 2 to give 3‐benzoyl‐2,4‐diphenylquinoline ( 22 ) directly, whereas no reaction occurs between 8 and 1 or 3 . Acetylene 9 does not react with 1, 2 , or 3 . The enamines exist as the intramolecularly hydrogen bonded isomers and usually undergo cyclization with 5 molar equivalents of methanolic sodium methoxide to give quinoline derivatives. The 4‐quinolinols exist predominantly as the 4‐quinolinone tautomer.