Structures of the products of formylation of 1,3,5-triphenyl- and 1,5 -diphenyl-3-stryl-2-pyrazolines

It was established by means of IR and PMR spectra and chemical transformations that the products of the Vilsmeier formylation of 1,3,5-triphenyl- and 1,5-diphenyl-3-styryl-2-pyrazolines are the corresponding 1-(p-formylphenyl)-2-pyrazolines. The frequencies of the stretching vibrations of the carbonyl group and the chemical shift of the aldehyde proton of these compounds indicate considerable conjugation of the p electrons of the N₁ atom of the pyrazoline ring with the aldehyde group.