Table 1.
Catalyst screen.

| entry | BINOL derivative | yield (%)a | d.r.b | ee (%)c |
|---|---|---|---|---|
| 1 | H (7) | 88 | 10:1 | 90 |
| 2 | 6,6'-(OMe)2 (22) | 63 | 6:1 | 82 |
| 3 | 6,6'-Br2 (23) | 65 | 8:1 | 86 |
| 4 | 3,3'-Me2 (24) | 63 | 8:1 | 90 |
| 5 | 3,3'-Br2 (17) | 63 | 16:1 | 90 |
| 6 | 3,3'-Cl2 (25) | 73 | 14:1 | 91 |
Isolated yield of exo:endo mixture.
Determined by 1H NMR analysis of crude reaction mixture.
Determined by HPLC using chiral stationary phase.