electrophilic substitution of 2,4-diaminopyridine by 2,6-disubstituted -4- [ ( n , n-dimethylamino ) methyl ] phenols and by halogens ( bromine and fluorine ) produces 3-benzyl and 3-halo derivatives , plus a small amount of disubstitution at the 3,5 positions .
C0018544
halogens
C0006223
bromine