| The continuous increase of CO2concentration in the atmosphere have become a hot topic in the media, political, and scientific filed in the recent years. Most people believe that the greenhouse effect of CO2causes the global climate change. While for the chemist, CO2is considered as a most attractive carbon resource since it is abundant, non-toxic and inexpensive. Transition-metal-catalyzed transformation of CO2with alkyne, alkene, and other carbon nucleophilic agents into carboxylic acid and derivatives have gained much advancement. However, duo to the flexibility of reaction system, broad substrate scope, easiness of manipulation, economical feasibility for the applications, and no heavy-metal impurities in product, transition-metal-free transformation of CO2exhibits its advantage and attract much more attentions.This dissertation built up a new transition-metal-free three-component reaction of primary amine, CO2and ethyl2-oxo-2-phenylacetate mediated by tris(dimethylamino)phosphine (P(NMe2>3), followed one-pot tandem cyclization reaction yielded synthetically important oxazolidine-2,4-diones. The optimized reaction condition were firstly set up:for the carboxylation raction,2-oxo-2-phenylacetates(1.0equiv), amines(1.2equiv), P(NMe2)3(1.4equiv), CO2(1atm), THF as solvent, temperature from-78℃to room temperature; for the cyclization reaction, MeONa (0.05equiv), toluene as solvent and120℃for1h. The substrate scope of this reaction system was then investigated. It turned out in the presence of tris(dimethylamino)phosphine, various aromatic amines, benzyl aminies, and aliphatic amines reacted with CO2and some a-keto ester smoothly to give a series of functionalized oxazolidine-2,4-dione compounds. All the products were characterized by NMR, IR, and HRMS. The structure of a product was confirmed by X-ray crystallography. The possible mechanism was proposed and primary exploration of synthetic application of this new reaction was also carried out. |
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