Investigation On The Synthesis Of 4,5-Disubstituted Pyrimidine Derivatives And 3,4-Diunsubstituted Coumarins

List et al published their work "Proline-Catalyzed Direct Asymmetric Aldol Reactions" in J. Am. Chem. Soc. and proposed enamine catalysis mode in 2000, which marked that the research field of organocatalysis officially entered into the chemists study topics. Generally, organocatalysis always deliveries a mild reaction condition with low cost, easy preparation, simple after treatment and low, pollution to the environment. In this thesis, we used an efficient route to synthesize 3,4-diunsubstituted coumarins and 4,5-disubstituted pyrimidine derivatives through organocatalytic cascade reactions.In the first part of this thesis, we used organocatalytic method to synthesizes 4,5-disubstituted pyrimidine derivatives. This reaction utilizing amine catalyst in situ reaction with ketones to form an enamine (as an electron-rich dienophile) and 1,3,5-triazine (electron-deficient diene) occurred inverse electron demand Diels-Alder reaction (IEDDA), simply and efficiently synthesized the 4,5-disubstituted pyrimidine derivatives. By optimizing the reaction conditions, screening of catalysts, selection of solvent, the amount of catalyst and reactants used in an amount proportional control, the optimal reaction condition was obtained in hand: L-Prolinamide as catalyst, the reaction was stirred at 90℃ in DMSO within 48 hours, delivering the corresponding production with high yields 80%-95%. Meanwhile, we developed a new method with organocatalytic inverse electron demand Diels-Alder reaction between 1,3,5-triazine with ketones to directly access to 4,5-disubstitut ed pyrimidine derivatives and proposed the plausible mechanism.In the second part, we have documented an efficient route to synthesize 3,4-di unsubstituted coumarins through an organocatalytic cascade reaction. Similar to the first part of the work, the reaction conditions were optimized by, screening of catalysts, selection of solvent, the amount of catalyst and reactants used in an amount proportional control, The reaction was catalyzed by using of a combination of benzylamine (10 mol%) and triethyl amine (10 mol%). A number of salicylaldehydes were tested, and the corresponding coumarin products were obtained in good to high yields under mild and metal-free reaction conditions. Moreover, a gram-scale synthesis was successfully amplified with prefer mild condition, which indicates that our method has built up a good basis for its potential application in industry.Finally, it is summarized and prospected in the view of the organocatalytic synthesis of pyrimidine and coumarin compounds researches.