Table 3.
Influence of phenyl substituents on yieldsa and selectivity (catalysts 7a–f, cf. Scheme 1).
catalyst | R | % yielda,b | % eec |
7a | Ph | 98 | 51 (R) |
7b | 3,5-(CF3)2-Ph | 95 | 42 (R) |
7c | 3,5-Cl2-Ph | 86 | 34 (R) |
7d | 3,5-F2 | 82 | 38 (R) |
7e | 4-NO2-Ph | 69 | 43 (R) |
7f | 4-OMe-Ph | 98 | 37 (R) |
aAll reactions carried out in benzene, 10 mol % cat., rt, 1 h. bIsolated yields. cChiral HPLC Daicel OJ, hexane/iPrOH 50:50, 1.0 mL/min, 254 nm, (S)-enantiomer: 12.3 min (R)-enantiomer: 26.0 min.