CO2 Adducts of α‐Carbon Alkylated N‐Heterocyclic Olefins: Highly Active Organocatalysts for CO2 Chemical Transformation

Abstract

AbstractA series of CO2 adducts of α‐carbon alkylated N‐heterocyclic olefins (ANHOs–CO2) were synthesized and characterized by single‐crystal X‐ray diffraction analysis. The in situ FTIR studies demonstrated that ANHOs–CO2 adducts showed higher thermal stability than the previously reported α‐carbon nonsubstituted N‐heterocyclic olefins (HNHOs–CO2) due to the enhancement of the electron‐donating properties. Moreover, ANHOs–CO2 adducts exhibit higher activity in catalyzing the carboxylative cyclization of CO2 with propargylic alcohols than HNHOs–CO2 under the same experimental conditions. Meanwhile, various internal and terminal functionalized propargylic alcohols could be tolerated to obtain the corresponding α‐alkylidene cyclic carbonates in moderate to good yields with high stereoselectivity.