Homolytic substitution of heteroaromatic compounds. Part II. Homolytic methylation of pyridine, quinoline, and isoquinoline in acidic and non-acidic media

Abstract

The effect of N-protonation on the homolytic methylation of pyridine, quinoline, and isoquinoline has been studied. The order of positional reactivities for the methylation of pyridine in non-acidic solution is 2 > 4 > 3, and the reactivities of positions 2 and 4 are enhanced in acidic media. Quinoline is methylated at positions 2,4,5, and 8 in non-acidic solution (8 > 4 > 5 > 2), and the reactivities of positions 2 and 4 are enhanced in acidic media. Isoquinoline gives 1-methylisoquinoline only in both acidic and non-acidic media.