Phosphine-thiourea as ligand for copper-catalyzed asymmetric (3+2) cycloadditions and kinetic resolution

Abstract

<p indent="0mm">Over the last decade, phosphine-(thio)ureas have been extensively used as bifunctional catalysts in a variety of asymmetric reactions <italic>via</italic> organophosphine or dual-reagent catalysis. By combination of phosphine-thioureas and copper salts in this article, we developed asymmetric cooperative catalysis which served as an efficient strategy for asymmetric (3+2) cycloadditions and kinetic resolutions. The reactions gave the pyrazolone scaffolds with high yields and good enantioselectivities. Broad substrate scope was demonstrated. Notably, the crystal structure of the active Cu(I)-species was obtained, providing valuable insight into the interaction of copper and phosphine-thioureas.