Abstract
In the thesis, a CoI2/(R)-BINAP, Zn, ZnI2 and H2O system efficiently catalyzed the intermolecular asymmetric reductive coupling of alkynes (1a-1g) with cyclic enones (2a-2d) at room temperature for 24 hour to afford highly enantioselective β-substituted cyclic enones. The reaction proceeds with highly regio- and stereoselectivity. In addition, by identify the absolute configuration of products 2.3a and 2.3f, a possible mechanism that involves the formation of cobaltacyclopentene intermediate from alkyne and cyclic enone is proposed. In addition, two different catalyzing system: CoBr2/dppe, Mn, ZnCl2, CH3CN and CoI2/BINAP, Zn, ZnI2, 1,4-dioxane, efficiently catalyzed the intermolecular reductive [3+2] cycloaddition of alkynes (1a-1l) with cyclic enones (2a-2e) at 40oC for 24 hour to afford highly stereoselective bicyclo[2.2.1]hept-2-en-1-ol and bicyclo[3.2.1]oct-6-en-1-ol derivatives respectively. This reaction also expanded a new reaction type of alkynes and enones in transition metal catalyzed reaction. We utilized the isotope experiment to further understand the mechanism. . Finally, we developed a new system: CoI2/(R,R′,S,S′)-Duanphos, Zn, ZnI2, 1,4-dioxane, efficiently catalyzed the intermolecular asymmetric reductive [3+2] cycloaddition of alkynes (1a-1i) with cyclic enones (2a-2e) at room temperature for 24 hour to afford highly enantio- and stereoselective bicyclo[2.2.1]hept-2-en-1-ol and bicyclo[3.2.1]oct-6- en-1-ol derivatives. In addition, by identify the absolute configuration of products 3.3a, a possible mechanism that involves the formation of cobaltacyclopentene intermediate from alkyne and cyclic enone is proposed. We discussed the result depend on alkyne and enones by asymmetric reductive coupling and asymmetric reductive [3+2] cycloaddition experiment, and further investigate the interdependent between these two reactions