Table 4.
| ||||
---|---|---|---|---|
entry | R | product | % yieldb | erc |
1 | CH3O | 11a | 13 | 57:43 |
2 | t-BuO | 11b | 25 | 65:35 |
3 | CH2=CHCH2O | 11c | 41 | 65:35 |
4 | CH3 | 11d | 52 | 70:30 |
5 | p-(CH3)2N-C6H4 | 11e | 76 | 97:3 |
6 | p-CH3O-C6H4 | 11f | 80 | 97.5:2.5 |
7 | p-Br-C6H4 | 11g | 83 | 96.5:3.5 |
8 | p-F-C6H4 | 11h | 84 | 97.5:2.5 |
9 | p-NO2-C6H4 | 11i | 92 | 99.5:0.5 |
10 | o-F-C6H4 | 11j | 83 | 69:31 |
11 | (E)-PhCH=CH | 11k | 82 | 95:5 |
12 | c-C6H11 | 11l | 83 | 97:3 |
Reactions were run with 0.125 mmol borane, 0.125 mmol acyl imine, 15 mol % catalyst and 3Å molecular sieves in toluene (0.1 M) for 24 h under Ar, followed by flash chromatography on silica gel.
Isolated yield.
Enantiomeric ratios determined by chiral HPLC analysis.