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1-Alkyl-1,4-dihydro-4-iminoquinoline-3-carboxylic Acids: Synthesis, Structure and Properties


T Van Es
B Staskun

Abstract

1-Alkyl-1,4-dihydro-4-iminoquinoline-3-carboxylates undergo neutral hydrolysis (in H2O or H2O-EtOH mixtures) to yield water-soluble 4-iminoquinoline-3-carboxylic acids and the corresponding 4-oxo esters. Such 4-imino acids are also accessed by treating an appropriate 1-alkyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid successively with thionyl chloride and an amine-H2O mixture, or from treatment of a 4-imino ester salt with aqueous amine. In the latter procedures 7-fluoro substituted substrates gave rise to 7-alkylamino derivatives even at room temperature. The title compounds are inferred to have an intramolecularly H-bonded charge transfer structure, and some of their chemical reactions and spectral (HRMS, 1H NMR) properties are described.


South African Journal of Chemistry Vol.55 2002: 13-33

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eISSN: 1996-840X
print ISSN: 0379-4350