Synthesis of new diheteroarylcarbazoles: a facile and simple route of 3,6-di(pyrazol-4-yl)carbazoles

A short and facile route to the synthesis of new 3,6-di(pyrazol-4-yl)carbazoles is reported. Dipyrazolylcarbazoles were synthesized in two steps from 3,6-diacetylcarbazoles through a Vilsmeier reaction which led to the formation of carbazolyl-β-chlorovinyl aldehydes, followed by cyclization with hydrazine hydrate. The reaction of the Vilsmeier reagent with hydrazones of diacetylcarbazoles yielded the corresponding pyrazole dicarbaldehydes in good yields.