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Substituent effects on the tautomer ratios between the enamine and methylene imine forms in side‐chained quinoxalines
Author(s) -
Kurasawa Yoshihisa,
Miyashita Ryuichiro,
Takada Atsushi,
Kim Ho Sik,
Okamoto Yoshihisa
Publication year - 1995
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.5570320249
Subject(s) - chemistry , tautomer , trifluoroacetic acid , sulfoxide , enamine , substituent , methylene , dimethyl sulfoxide , imine , medicinal chemistry , organic chemistry , catalysis
The p ‐ and m ‐substituted 3‐arylcarbamoylmethylene‐2‐oxo‐1,2,3,4‐tetrahydroquinoxalines 3a‐o showed the tautomeric equilibria between the enamine C and methylene imine D forms in dimethyl sulfoxide or dimethyl sulfoxide/trifluoroacetic acid media. The linear correlation of the Hammett σ p and σ m values with the log K T values was observed in the dimethyl sulfoxide/trifluoroacetic acid (2:1) media of compounds 3a‐o , wherein K T meaned the tautomeric equilibrium constants ([D]/[C]).