Asymmetric catalytic arylation of ethyl glyoxylate using organoboron reagents and Rh(i)–phosphane and phosphane–phosphite catalysts

Herein we report the first application of Rh(i)-phosphane and phosphane-phosphite catalysts in the enantioselective catalytic arylation of ethyl glyoxylate with organoboron reagents, providing access to ethyl mandelate derivatives in high yield (up to 99%) and moderate to very good enantioselectivities (up to 75% ee). Commercial phosphane ligands, such as (R)-MonoPhos and (R)-Phanephos were tested, as well as non-commercial (R,R)-TADDOL-derived phosphane-phosphite ligands. Those ligands containing bulky substituents in the ortho-and para-positions of the chiral phosphite moiety were found to be the most selective.