Carbonylative ring expansion of oxetane into γ‐butyrolactone using bimetallic cobaltate catalysts: Insight into the deactivation mechanism

Abstract

Abstractγ‐butyrolactones and their derivatives serve as the fundamental building blocks for a wide range of biologically significant and synthetically challenging natural products, which find extensive applications in various high‐demand chemicals. In this study, we have successfully established a facile and atom‐efficient synthesis of γ‐butyrolactones through the carbonylative ring expansion of oxetanes. We employed both homogeneous and heterogenized bimetallic catalysts ([HCP‐TPPM][Co(CO)4], where HCP refers to hyper cross‐linked polymer and TPP denotes tetraphenylporphyrin, with M = Cr3+ and Al3+). While the homogeneous catalysts exhibited remarkable activity, the heterogeneous catalysts offered the distinct advantages of facilitating product separation and enabling catalyst recycling. Notably, during the catalyst recycling studies, we observed a decrease in catalytic activity attributed to cobaltate leaching. The hypothesis of cobaltate leaching through β‐hydrogen elimination was validated by comparative studies using substrates with and without β‐hydrogen in both batch and continuous flow catalytic processes.