Synthesis of monomeric and oligomeric 1,1′-methylenebis-(1H-pyrazoles) contaning ethynyl fragments

1,1′-Methylenebis(1H-pyrazole) and 1,1′-methylenebis(3,5-dimethyl-1H-pyrazole) reacted with iodine in the presence of iodic acid to give the corresponding 4,4′-diiodo derivatives. Polycondensation of the latter with p-diethynylbenzene led to the formation of oligomeric compounds. 1,1′-Methylenebis(4-iodo-1H-pyrazoles) were converted into 4,4′-diethynyl derivatives by the Sonogashira and reverse Favorskii reactions, and their oxidative polycondensation in the presence of copper(I) chloride in pyridine also gave oligomeric products with a molecular weight exceeding 9000.