Convenient divergent strategy for the synthesis of C3*-TunePhos ligands and their applications in highly enantioselective Ru-catalyzed hydrogenations

ORGN 673

Wei Li, wzl116@psu.edu1, Xianfeng Sun, xus103@psu.edu1, and Xumu Zhang, xumu@rci.rutgers.edu2. (1) Department of Chemistry, The Pennsylvania State University, 104 Chemistry Research Building, University Park, PA 16802, (2) Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, NJ 08854
A convenient, remarkably versatile strategy for the syntheses of a series of modular and fine-tunable C3-TunePhos-type chiral diphosphine ligands was developed and their applications in highly efficient Ru(II)-catalyzed asymmetric hydrogenations were explored. Up to 97 and 99% ee values were achieved for the enantioselective syntheses of chiral β-methyl amines and chiral α-hydroxy acid derivatives, respectively. The C3*-TunePhos/diamine-Ru(II) complex combined with t-BuOK in 2-propanol effectively catalyzed enantioselective hydrogenation of a wide range of unfunctionalized ketones including aromatic, heteroaromatic, α,β-unsaturated, and cyclopropyl ketones, affording high reactivity (up to 1,000,000 TON) and excellent enantioselectivities (>99% ee).