A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones

Abstract

Abstract The rapid development of enantioselective C−H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C 5 H 2 t Bu 2 CH 2 t Bu)RhI 2 ] 2 in two steps from commercially available [(cod)RhCl] 2 and tert ‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural ( S )‐proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee ).