Origins of Catalyst-Controlled Chemoselectivity in Transition-Metal-Catalyzed Divergent Epoxide Conversion

Transition-metal-catalyzed transformation reactions ofepoxidescan provide practical C2 synthons in synthetic chemistry. These reactionsoffer a feasible strategy for catalyst-controlled epoxide divergenttransformations. Therefore, finding out the crucial factors controllingchemoselectivity is the key to the rational design of transition-metal-catalyzeddivergent conversions with high selectivity. In these studies, wehave selected and systematically explored the general mechanism ofboth Mn-(CO)(5) (-)- and Co-(CO)(4) (-)-catalyzed divergent epoxide transformations associatedwith different products, namely, alkenes and beta-lactones. Ourcomputational studies showed that the chemoselective reaction undergoeseither a retro-[3 + 2] step forming an alkene or a carbonyl migrationinsertion step for generating a beta-lactone. For the Mn-catalyzedreaction, the energy barrier of the retro-[3 + 2] step is lower thanthat of the carbonyl migration insertion step, but the case is reversedin the Co-catalyzed reaction. Further analysis revealed that the spatialconfigurations of metal complexes and Pauli repulsion controlled bythe metal atomic radius could be responsible for the phenomenon. Theinsights obtained are not only important for understanding chemoselectivitydetermined by the inherent properties of transition metals but alsoprovide a valuable case for studying transition-metal-catalyzed reactionswith catalyst-controlled chemoselectivity.

Automated summary

Transition-metal-catalyzed transformation reactions of epoxides provide practical C2 synthons and a feasible strategy for catalyst-controlled divergent conversions. Understanding the crucial factors controlling chemoselectivity is key to rational design. Computational studies reveal that the chemoselective reaction can undergo a retro-[3 + 2] step or a carbonyl migration insertion step, influenced by the energy barriers and metal complexes configurations. These insights are important for understanding chemoselectivity and catalyst-controlled reactions.