Synthesis and Transformations of Hydrazine-Substituted Pyrano[3″,4″:5′,6′]pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine

A method was developed for the synthesis of 11-(2-furyl)-4-hydrazino-8,8-dimethyl-7,10-dihydro-8H-pyrano[3″,4″:5′,6′]pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine on the basis of which new heterocyclic systems were synthesized. The conditions for the azido/tetrazole transformation of the resulting condensed tetrazolo[1,5-c]pyrimidine were studied. Isomeric triazolo[4,3-c]- and -[1,5-c]pyrimidines were synthesized and the conditions for the transformation of the first isomer into the second in accordance with the Dimroth rearrangement were established.