The reaction of 6-iodo-, 9-benzyl-6-chloropurine and 7-benzyl-6-chloropurine with butyl acrylate, acrylonitrile, methyl vinyl ketone or methyl methacrylate under conditions of the Heck reaction in the presence of TlOAc or AgOAc afforded N1-alkylhypoxanthine derivatives. Formation of these unexpected products can be rationalised as a Tl+- or Ag+-assisted substitution of halogen with acetate anion. The 6-acetoxypurine derivative thus formed then eliminates ketene and gives 7-benzyl- or 9-benzylhypoxanthine. Conjugate addition of these compounds onto Michael acceptors furnishes the N1-substituted hypoxanthine derivatives.
6-
碘-、9-苄基-
6-氯嘌呤和7-苄基-
6-氯嘌呤与
丙烯酸丁酯、
丙烯腈、
甲基乙烯酮或甲基
甲基丙烯酸酯在Heck反应条件下,在TlOAc或AgOAc存在下反应,生成N1-烷基
次黄嘌呤衍
生物。这些意外产物的形成可以解释为Tl+或Ag+-辅助卤素与
乙酸根离子的置换反应。因此形成的6-乙酰氧
嘌呤衍
生物随后消除酮烯并生成7-苄基或9-苄基
次黄嘌呤。这些化合物的共轭加成到Michael受体上形成N1-取代
次黄嘌呤衍
生物。