Implications of Active Intermediate and Olefin Attachment Position in the Piperine Metathesis

Abstract: First and second generation of Grubbs catalysts (G1 and G2) were applied in the piperine olefin metathesis under different conditions. G1 was used in self-metathesis, G2 was implemented in both, self and cross-metathesis of piperine with eugenol. Results allowed to implicate about the main intermediate of the reaction and the position of olefin attachment to the catalyst, assuming that the reaction follows a pathway where 2A=B olefin leads to the formation of A=A and B=B. In addition, the results contributed to the studies of catalyst’s reactivity when the olefin metathesis product required the high electronic effect of the N-heterocyclic of G2. In this paper, the highest activity of G2 in the olefin metathesis of eugenol was observed when the first intermediate was Ru-eugenol-moiety in the cross-metathesis of the piperine with eugenol. This demonstrates that the acidity of the new carbene in the intermediate species causes inactivity only in the reaction with piperine.