Derivatives of condensed thienopyrimidines 12. Synthesis of substituted pyrano(thiopyrano)-[4′,3′:4,5]thieno[2,3-d]pyrimidines
A method for the synthesis of new condensed derivatives of 4-oxo-2-thioxo-5,6-dihydro-8H-pyrano(thiopyrano)[4′,3′:4.5]thieno[2, 3-d]pyrimidines has been developed. It has been established that with increasing electron acceptor ability of the substituents