PtAu bimetallic nanocatalyst for selective hydrogenation of alkenes over aryl halides

Herein, we present a new strategy that for the first time achieved chemo- and enantio-selective hydrogenation of alkenes over arylhalides. Key to the success is that instead of using external poisons, we use the composition of the bimetallic nanocrystal catalysts to control chemoselectivity (hydrogenation of C=C bonds without cleavage of Ar-X bonds). We further show that this system combined with surface modifying chiral ligands can control the enantioselectivity. Thus, after synthesizing and screening a series of easily accessible M_xAu_y (M = Pd, Pt; x, y = 1, 3, 5) bimetallic nanocrystals (9–10 nm) supported on activated carbon, we identified that Pt₁Au₁/C is a recyclable and generally applicable catalyst for the chemoselective hydrogenation of alkenes without cleaving aryl halogen bonds. Furthermore, cinchonidine modified Pt₁Au₁/C is shown to be capable of enantioselective hydrogenation, as illustrated by the rapid and enantio-enriched synthesis of RIP1 inhibitor analogue 7-Br-O-Nec1.