| This thesis includes three parts regarding theoretic studies of organic reactions. Part one is concerned with an in-depth understanding of the mechanism and diastereoselectivity of the Kulinkovich hydroxycyclopropanation reaction. In part II, efforts are devoted to the understanding of the reaction mechanism and regiochemistry of a series of cascade reactions involving the participation of aromatic dienophiles such as amino-substituted pyrrole, imidazole and pyrazole derivatives. Meanwhile, in this part, the relationship between the reactivity and aromaticity of the aromatic dienophiles in participating in Diels-Alder reactions has been established. The last part of this thesis focuses on a theoretical comparison of the Reactions of 5-alkoxyoxazole with thioaldehyde, nitroso compound and aldehyde. Especially, the origins of the regiochemistry and stereochemistry of the Lewis acid catalyzed reactions between aldehyde and 5-alkoxyoxazole to furnish 2-oxazoline-4-carboxylates have been explored in order to gain some insights that would be instrumental for future design of robust catalyst. |
