Rhodium‐Catalyzed Asymmetric Arylation‐Induced Glycolate Aldol Additions of Silyl Glyoxylates

(Diene)Rh(I) complexes catalyze the stereoselective three‐component coupling of silyl glyoxylates, arylboronic acids, and aldehydes to give glycolate aldol products.  The participation of Rh‐alkoxides in the requisite Brook rearrangement was established through two component Rh‐catalyzed couplings of silyl glyoxylates with ArB(OH)2 to give silyl‐protected mandelate derivatives. The intermediacy of a chiral Rh‐enolate was inferred through enantioselective protonation using a chiral Rh‐catalyst.  Diastereoselective three‐component couplings with aldehydes as terminating electrophiles to give racemic products were best achieved with a bulky aryl ester on the silyl glyoxylate reagent. Optimal enantioselective couplings were carried out with the tert‐butyl ester variant using an anisole‐derived enantiopure tricyclo[3.2.2.02,4]nonadiene ligand.