Table 1.

Reaction optimization

Reactions were carried out on a 0.20 mmol scale (1a) using trans-PhCH=CHB(OH)₂ (2a) (0.30 mmol), 5 mol% nickel salt, 7.5 mol% ligand in unpurified TFE (2.0 mL) in a test tube for 24 h which was opened to air

^aIsolated yields

^bDetermined by HPLC using a chiral Enantiocol column. TFE = trifluoroethanol, NR = no reaction, ee = enantiomeric excess