Regioselective synthesis of quinolin-8-ols and 1,2,3,4- tetrahydroquinolin-8-ols by the cyclization of 2-(3-hydroxyphenyl)ethyl ketone 0-2,4-dinitrophenyloximes

Article abstract of DOI:10.1246/bcsj.71.2945

Cyclization of 2-(3-hydroxyphenyl)ethyl ketone 0-2,4- dinitrophenyloximes proceeds on the oxime nitrogen atom by the treatment with NaH and then with 2,3-dichloro-5,6-dicyano-p-benzoquinone and acetic acid to yield quinolin-8-ols regioselectively. The reaction in the presence of Na[BH₃(CN)] affords 1,2,3,4-tetrahydroquinolin-8-ols. The present cyclization proceeds via alkylideneaminyl radical intermediates generated by the single electron transfer between 3-hydroxyphenyl and 2,4-dinitrophenyl moieties.