Deuterium studies in the disproportionation of pyrimido[4,5-b]quinolinium salts

Abstract

Treatment of 4-chloro-6-N-alkylanilino-5-for-mylpyrimidines (1) with ethanolic hydrochloric acid gave high yields of 10-alkyl-pyrimido[4,5-b]quinolinium-4(3H)-ones (2; R²= H) which, at pH 9, underwent disproportionation to corresponding 10-alkyl-5,10-dihydropyrimido[4,5-b]quinolin-4(3H)-ones (3) and 10-alkyl pyrimido[4,5-b]quinolin-4,5(3H,10H)-diones (4); disproportionation of a 5-deuterio-salt (6) gave a 10-alkyl-5,5-dideuteriopyrimido[4,5-b]quinoline showing that the reaction involved hydride (deuteride) transfer from the 5-position of one molecule to the 5-position of another.