Cyclazines and their analogs. 4. Synthesis of triazolopyrido[1,2-c]pyrimidines

Alkylation of isomeric 2-mercapto-6- and 4-mercapto-2-methylpyrimidines by ethyl -bromoacetoacetate yields the corresponding S-substituted pyrimidines. Formylation of these intermediates by the Vilsmeier reagent gives diformyl derivatives of a new cyclazine series, namely, thiazolopyridopyrimidines. These cyclazine dialdehydes react with nucleophilic reagents used for the synthesis of polymethine dyes to give highly colored biscyanines. The interrelationship between the color and structure of these heterocyclic products and derived dyes was analyzed.For Communication 3, see [1].Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 252660 Kiev, Ukraine. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 392–395, March, 1998.