Reactivity of 1-methyl-2 (1H)-thiopyridone (I), 1-methyl-2 (1H)-thioquinolone (III), and 2-methyl-1 (2H)-thioisoquinolone (V) was compared with that of the corresponding oxygen compounds, 1-methyl-2 (1H)-pyridone (II), 1-methyl-2 (1H)-quinolone (IV), and 2-methyl-1 (2H)-isoquinolone (VI). In deuteration, I was less reactive than II, III entirely failed to react, and V reacted under a stronger reaction condition than VI. Bromination of I and V was carried out but they did not produce the expected products, although II and VI reacted easily. Grignard reaction as an example of the nucleophilic substitution reactions on III, which was most inactive to the electrophilic substitution reactions, revealed that III is more inactive than IV to this reaction and the yield was not good even under a more drastic condition.
