N-1-substituted hypoxanthine derivatives from the reaction of 6-halopurines with Michael acceptors under the conditions of Heck reaction

The reaction of 6-iodo-, 9-benzyl-6-chloropurine and 7-benzyl-6-chloropurin e with butyl acrylate, acrylonitrile, methyl vinyl ketone or methyl methacr ylate under conditions of the Week reaction in the presence of TIOAc or AgO Ac afforded N-1-alkylhypoxanthine derivatives. Formation of these unexpecte d products can be rationalised as a Tl+- or Ag+-assisted substitution of ha logen with acetate anion. The 6-acetoxypurine derivative thus formed then e liminates ketene and gives 7-benzyl- or 9-benzylhypoxanthine. Conjugate add ition of these compounds onto Michael accepters furnishes the N-1-substitut ed hypoxanthine derivatives.