A series of phosphorus ylide (P-ylide) CO 2 adducts were synthesized and firstly used as organocatalysts for CO 2 transformation. Detailed studies on the cycloaddition reaction of CO 2 with terminal epoxides show that P-ylide CO 2 adducts are efficient metal-free and halogen-free organocatalytsts to mediate this reaction under ambient conditions (25 o C, 1 atm CO 2 ). More importantly, the reactions proceeded with a broad scope, high efficiency, and functional group tolerance and the corresponding cyclic carbonate products were obtained in good to excellent yield (46-99%). Meanwhile, the kinetic study by in-situ FTIR method suggested an intermolecular cooperation effect for effectively accelerating the ring-opening of terminal epoxides. Furthermore, from the investigation on the catalytic diversity of Pylide CO 2 adducts, CO 2 also could be availably converted to functionalized cyclic αalkylidene carbonates, oxazolidinone, N-methylated and N-formylated amines by organocatalytic reactions.

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As eries of CO 2 adductso fa-carbona lkylated Nheterocyclic olefins(ANHOs-CO 2 )were synthesized and characterized by single-crystalX -ray diffractiona nalysis. The in situ FTIR studies demonstrated that ANHOs-CO 2 adducts showed higherthermal stabilitythan the previously reported a-carbon nonsubstituted N-heterocyclic olefins (HNHOs-CO 2 )d ue to the enhancement of the electron-donating properties. Moreover,A NHOs-CO 2 adducts exhibit higher activity in catalyzingt he carboxylative cyclization of CO 2 with propargylic alcohols than HNHOs-CO 2 under the same experimental conditions. Meanwhile, variousi nternal and terminal functionalized propargylic alcohols could be tolerated to obtain the corresponding a-alkylidenec yclic carbonates in moderate to good yields with high stereoselectivity.

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