Fig. 5: Divergent synthesis of all four isomers of chiral hindered ether 3b or 4a.

All reactions were carried out on a 0.15 mmol scale with 1 eq precursor of 1b, 1.05 eq 2a, 10 mol% of (S)-Ca[A]2 and 5 mol% of (R)-L3[(NCMe)AuSbF6] or 2.5 mol% of (R)-L6[(NCMe)AuSbF6]2 in DCE (1 mL) at −25 °C. Isolated yield. d.r. was determined by crude 1H-NMR and ee values were determined by chiral HPLC.