[2+2+2]-Co-cyclotrimerization 6-alkynylpurines with diynes: a method for preparation of 6-arylpurines

A novel approach to 6-arylpurines based on [2+2+2]-co-cyclotrimerization of 6-alkynylpurines with various α,ω-diynes is described. Co-cyclotrimerization is catalyzed by Ni- and Co-phosphine catalysts and their choice depends on the substitution pattern of the both reactants.