Heterocyclic studies. Part XXXIX. Ring cleavage of some pyrimidine derivatives in alkali

Abstract

4-(Substituted amino)-6-chloropyrimidines bearing a mesomeric electron-withdrawing substituent such as NO₂, CN, CHO, or Ac at position 5 are cleaved by dilute sodium hydroxide, often at room temperature, to yield tetrasubstituted olefins. Unlike acid-catalysed attacks on similar pyrimidines, the course of these basic reactions was not strongly influenced by steric interference between the 4(6)- and 5-substituents.