Impact of the Olefin and Diazene Structure on the Heterofunctional Azo Metathesis Catalyzed by the First-Generation Grubbs Catalyst

In this work, we computationally studied the influence
of the change
in the substrate structure on the course of the heterofunctional cross-metathesis
reaction between azo compounds and olefins catalyzed by the first-generation
Grubbs catalyst. The highest reaction rates were predicted for symmetric,
bulky diazenes and sterically uncrowded olefins. Other studied azo
compounds have much higher energy barriers in the crucial steps in
the catalyst initiation phase, while larger olefins are characterized
by high energy barriers in the second part of the catalytic cycle.
Our analysis suggests that Grubbs-like catalysts can be efficiently
used in heterofunctional azo metathesis only for a limited number
of olefin-azo compound combinations, such as 1,2-diphenyldiazene and
ethylene to produce N-phenylmethanimine.