Hetero-ring lithiation of N-methyl-4-quinolone and N-methylquinoline-4-thione

Lithiation of 1-methyl-4-quinolone and 1-methylquinoline-4-thione with lithium diisopropylamide (LDA) at –78 °C takes place at C-2. The resulting lithio-species react with a variety of electrophiles to give 2-substituted-4-quinolones and -quinolines-4-thiones respectively. 1-Methylquinoline-4-thione is easily converted into 1-methyl-4-quinolone in protic solution.