Theoretical Study On The Reaction Mechanism Of L-Proline Catalyzed Synthesis Of Two Kinds Of Nitrogen Heterocycles Compounds

In this paper, the Gaussian 09 program was used to explore the reaction mechanism of the synthesis about two kinds of nitrogen heterocycles compounds catalyzed by L-proline——pyrido[2,3-d]pyrimidines and pyrazolo[3,4-b]pyridines. For all the reactants, intermediates, transition states and products in the mechanism, their structural optimization, frequency, NBO charge and the activation energy were calculated in ethanol solvent(IEFPCM model) by the basis of B3LYP/6-31G(d,p)on Density Functional Theory. Moreover, Intrinsic Reaction Coordinate(IRC) was employed in all the transition states to verify their correctness.Our article consist of two projects. The first project mainly studied the mechanism of the synthesis on pyrido[2,3-d]pyrimidines via three-component one-pot domino reaction and catalyzed by L-proline. There are two reactions were studied in this project. The reactants of first one were formaldehyde,6-amino-1,3-dimethyluracil, and dialkyl acetylenedicarboxylates, while the second reaction used benzaldehyde to substitute the formaldehyde in first reaction. We designed pathway A and B for each reaction, and the difference between these two path was stereo structure of their intermediates and the transition states. In addition,two kinds of different transition states were also designed, which based on if there were H2 O supporting the proton-transfer process. Finally, with the comprehensive analysis of a variety of data calculated above, the path B with H2 O supporting the proton-transfer process was the reaction of L-proline catalyzed synthesis of pyrido[2,3-d]pyrimidines compounds.The second project mainly studied the mechanism of synthesis about pyrazolo[3,4-b]pyridines via three-component one-pot domino reaction with the catalyst L-proline. N-methyl-1-(methylthio)-2-nitroprop-1-en-1-amine, aromatic alde-hydes, and 3-methyl-1-aryl-1H-pyrazol-5-amines were the three reactants. In this part, we designed the mechanism of this reaction and calculated it. By comprehensive analysis of all data, the mechanism of L-proline catalyzed synthesis of pyrazolo[3,4-b]pyridines was obtained.