Fig. 2: Scope of sulfonyl substitution on nitrogena.

aReaction conditions: unless otherwise noted, the reactions were conducted with 1 (0.1 mmol), Co(OAc)2 (10 mol%), L1 (12 mol%), and DABCO (40 mol%), in acetone/EtOH (3 mL/1 mL) at −30 °C. Isolated yields. The d.r. was determined by 1H NMR analysis of the crude mixture of products. The ee values were determined by UPC2 or HPLC.