Diastereo- and Enantioselective 1,6-Conjugate Addition of 2-Azaarylacetamides to para-Quinone Methides

A chiral Mg(II)/N,N'-dioxide complex was found to be highly effective in promoting the diastereo- and enantioselective 1,6-conjugate addition of various azaarylacetamides to p-quinone methides under mild reaction conditions. Various chiral azaarene derivatives containing gem(1,1)-diaryl skeletons were obtained in good yields, dr, and excellent ee values. Meanwhile, on the basis of insight gained from the control experiments as well as the single-crystal structure of the Mg(II)/N,N'-dioxide complex and product, a possible transition state was proposed to explain the origin of coordination and stereoinduction.