Impact of Lewis acid catalyst on the regioselectivity and kinetics of 1,3-dipolar cycloaddition reaction of azidobenzene with acrolein: a theoretical study using DFT

In the present work, impact of Lewis acid (LA) catalysts BF3, BCl3, and BBr3 on the kinetics andregioselectivity of 1,3-dipolar cycloaddition (1,3-DC) reaction between azidobenzene and acroleinwas theoretically studied using B3LYP/6-31G* level. Our results indicate while the uncatalyzed 1,3-DC reaction under investigation takes place via a non-polar, non-regioselective, and lowasynchronous process, the LA catalyzed 1,3-DC reaction takes place via a polar, regioselective, andhigh asynchronous process. In addition, the barrier height of the studied 1,3-DC reaction isconsiderably reduced in the presence of LA catalysts, and the catalytic activity of LAs in order toincrease the electrophilicity character of acrolein and, consequently, to reduce barrier height ofreaction, is increased with the increase of halogen atom size; BBr3> BCl3> BF3. Regioselectivity inthese LA catalyzed 1, 3-DC reactions appears to be controlled by steric repulsion effects between theLA catalyst and the azide phenyl substituent instead of the electronic effects.