Concerning Model Metabolites of the Carcinogen 4-Nitroquinoline 1-Oxide. Reactivity of 1-Acetoxy-4-(hydroxyimino)-1,4-dihydroquinoline

Article abstract of DOI:10.1021/jo00263a027

1-Acetoxy-4-(hydroxyimino)-1,4-dihydroquinoline is obtained by hydrolysis of 1-acetoxy-4-(acetoxyimino)-1,4-dihydroquinoline under strongly acidic conditions.At pH <1 the monoacetate is protonated and on hydrolysis affords only 1-hydroxy-4-(hydroxyimino)-1,4-dihydroquinoline.Above pH 1 on hydrolysis the monoacetate affords a complex product mixture including 4-(hydroxyamino)quinoline and 4-nitrosoquinoline.Comparison of the above behavior of 1-acetoxy-4-(hydroxyamino)-1,4-dihydroquinoline with that of 1-hydroxy-4-(acetoxyimino)-1,4-dihydroquinoline at a neutral pH suggests that the former type of ester is less likely to be important in those steps initiating oncogenesis.In contrast the latter type of monoester or diesters corresponding to 1-acetoxy-4-(acetoxyimino)-1,4-dihydroquinoline by their ability to generate nitrenium ion intermediates and undergo attack by nucleophiles at the 3-position are likely intermediates in the process of oncogenesis.Further aspects of their likely biological role are discussed.