Fig. 4: Preparation of bridged atropisomers with a single stereogenic axisa.

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. bR6 = Mesitylene-2-sulfonyl. cR6 = Tosyl. Isolated yields. The ee values were determined by UPC2 or HPLC.