Allylic amines are important structures found in biologically active compounds and valuable intermediates for a number of pharmaceutical applications. Because of their importance in medicinal chemistry and organic synthesis, lots of methods for the preparation of allylic amines have been studied. Of the various protocols, regioselective aza-Michael addition of (hetero)arylamines to dienes is one of the most effective and atom-economy strategies. In this study, we developed a new copper catalytic system for the synthesis of allylic amines through 1,6-aza-Michael addition of (hetero)arylamines to sulfonyl-substituted dienes. Copper-catalyzed aza-Michael addition is attractive because it uses inexpensive, environmentally benign and easy-to-handle copper catalyst. The 1,6-addition of heterocycles to sulfonyl-substituted dienes was promoted by the presence of 7.5 mol % NHC-CuCl and 7 mol % KO<i>t</i>-Bu and selectively proceeded to complete conversion in toluene, affording sulfonyl-substituted allylic amines. It was found that a sterically demanding NHC ligand played an important role in enhancing its reactivity and controlling regioselectivity. This catalytic process provided versatile and new allylic amines in high yields with excellent regioselectivity.

Synthesis of allylic amines through Cu-catalyzed aza-Michael addition of heterocycles to dienes

2019 Fall National Meeting

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