Catalytic enantioselective 1,3-dipolar cycloadditions of nitrones with propioloylpyrazoles and acryloylpyrazoles induced by chiral [pi]-cation catalysts

The enantioselective catalysis of 1,3-dipolar cycloaddition reaction of nitrones with propioloylpyrazole and acryloylpyrazole derivatives in presence of a chiral copper(II) complex of 3-(2-naphthyl)-L-alanine amide is described. The reaction is the first successful method for the catalytic enantioselective 1,3-dipolar cycloaddition of nitrones with acetylene derivatives.