Kinetics of the heterocyclization of (E)-1,5-diphenylpent-1-en-4-yn-3-one phenylhydrazone in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene

Abstract

The kinetics of the cyclization of (E)-1,5-diphenylpent-1-en-4-yn-3-one phenylhydrazone in ethylene glycol in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene at temperatures ranging from 373.15 to 407.15 K was studied. The reaction product is (E)-1,2-diphenyl-4-styryl-1H-pyrazole in a yield of 99%. The use of catalysis allows one to shorten the reaction time with retaining the yield of the product. The mechanism of the formation of a complex between the reactant and catalyst and the proton transfer from the reactant to the catalyst, which decreases the activation barrier for cyclization, is considered.