Reactions of 5-chloro-2-methylsulfonyl-4-pyrimidinecarboxylic acid and its esters with amines. The inverse of reactivity in a pyrimidine ring

Reactions of 5-chloro-2-methylsulfonyl-4-pyrimidinecarboxylic acid with aliphatic amines afford 2-amino-5-chloro-4-pyrimidinecarboxylic acid, whereas 5-chloro-2-methylsulfonyl-4-pyrimidinecarboxylates form 5-amino-2-methylsulfonyl-4-pyrimidinecarboxylates under the same conditions.