Table 1. Evaluation of Conditions for Cobalt-Catalyzed Asymmetric Hydroboration of α-Trifluoromethyl Styrene 1a^a.

^aConditions: α-trifluoromethyl styrene 1a (0.100 mmol), HBpin (0.120 mmol), Co(acac)₂ (3.0 μmol), ligand (4.0 μmol), Li(acac) (30 μmol), 2-Me-THF (0.1 mL) at rt. for 48 h, conversions of 1a, and ratios of 2a:4a were determined by GC analysis with tridecane as the internal standard, isolated yields were given, and ee values of 4a were determined by chiral HPLC analysis.