Highly Exo-Selective and Enantioselective Cycloaddition Reactions of Nitrones Catalyzed by a Chiral Binaphthyldiimine−Ni(II) Complex
摘要:
Significant levels of exo-selectivity (exo:endo = > 99:1 to 86:14) and enantioselectivity (95-82% ee) were obtained in the 1,3-dipolar cycloadditions of a number of nitrones with 3-(2-alkenoyl)-2-thiazolidinethiones, using the chiral binaphthyidiimine-Ni(II) complex (5-20 mol %), which was easily prepared form N,N'-bis(3,5-dichrolo-2-hydroxybenzylidene)-1,1'-binaphthyl-2,2'-diamine and Ni(ClO4)2(.)6H(2)O in CHCl3 in the presence of 4 angstrom molecular sieves, as a chiral Lewis acid catalyst.
Highly Exo-Selective and Enantioselective Cycloaddition Reactions of Nitrones Catalyzed by a Chiral Binaphthyldiimine−Ni(II) Complex
摘要:
Significant levels of exo-selectivity (exo:endo = > 99:1 to 86:14) and enantioselectivity (95-82% ee) were obtained in the 1,3-dipolar cycloadditions of a number of nitrones with 3-(2-alkenoyl)-2-thiazolidinethiones, using the chiral binaphthyidiimine-Ni(II) complex (5-20 mol %), which was easily prepared form N,N'-bis(3,5-dichrolo-2-hydroxybenzylidene)-1,1'-binaphthyl-2,2'-diamine and Ni(ClO4)2(.)6H(2)O in CHCl3 in the presence of 4 angstrom molecular sieves, as a chiral Lewis acid catalyst.
Significant levels of exo-selectivity (exo:endo = > 99:1 to 86:14) and enantioselectivity (95-82% ee) were obtained in the 1,3-dipolar cycloadditions of a number of nitrones with 3-(2-alkenoyl)-2-thiazolidinethiones, using the chiral binaphthyidiimine-Ni(II) complex (5-20 mol %), which was easily prepared form N,N'-bis(3,5-dichrolo-2-hydroxybenzylidene)-1,1'-binaphthyl-2,2'-diamine and Ni(ClO4)2(.)6H(2)O in CHCl3 in the presence of 4 angstrom molecular sieves, as a chiral Lewis acid catalyst.