fig2

Figure 2. Reaction Scope^[a]. [a] Reaction conditions:1a (0.05 mmol), DDQ (0.55 mmol), H1 (0.075 mmol), catalyst (10 mol%), solvent (1.0 mL). The yield was determined to be > 95% in all the cases by ¹H NMR and TLC analyses of the crude reaction mixture; ee value was determined by chiral HPLC analysis. [b] Run with 0.5 mol% of catalyst. Solvent (0.18 mL, c = 0.28 M). [c] Run for 36 h. [d] Run at -10 ^oC, 1a (0.4 mmol), DDQ (0.44 mmol), H1 (0.6 mmol), solvent (1.44 mL), 96 h.