Theoretical Model for N-Heterocyclic Carbene-Catalyzed Desymmetrizing [4+1] and [4+2] Annulations of an Enal and Aryldialdehyde with 1,3-Cyclopentenedione

N-Heterocyclic carbene (NHC) catalyzed desymmetrizing reactions of olefins have rapidly developed in recent years; however, the origins of the chemo- and stereoselectivities of these reactions remain poorly understood. Herein, we propose a mechanistic map for these reactions to predict how chemo- and stereoselectivities are controlled by different active intermediates (i.e., Breslow and acylazolium intermediates). Remarkably, our findings contradict a previous proposition that product structures are determined by a transformation between a pair of isomers.

Automated summary

Desymmetrizing reactions of olefins catalyzed by N-Heterocyclic carbene (NHC) have been rapidly developing, but the origins of the chemo- and stereoselectivities in these reactions are still poorly understood. This study proposes a mechanistic map to predict how these selectivities are controlled by different active intermediates and contradicts a previous proposition regarding the determination of product structures by a transformation between a pair of isomers.