Table 4.
| |||||||
---|---|---|---|---|---|---|---|
entry | cat 10 (equiv) | BH3–THF (equiv)a | T (°C) | solvent | time (h) | isolated yield (%)b | ee (%)c |
1 | 0.1 | 5.0 | 0 | THF | 72 | 50 | 8 |
2 | 1.0 | 5.0 | 0 | THF | 96 | 46 | 13 |
3 | 1.0 | 2.0 | 10 | dioxane | 72 | 57 | 60 |
4 | 1.0 | 3.0 | 10 | dioxane | 48 | 71 | 57 |
5 | 1.0 | 4.0 | 10 | dioxane | 48 | 79 | 73 |
6 | 0.3 | 5.0 | 10 | dioxane | 72 | 34 | 4d |
7 | 1.0 | 2.0 | 10 | dioxane | 48 | 73 | 54e |
Stabilized with NaBH4.
Isolated yield of amide.
Determined by GC of acetyl derivatives on a chiral column (CP-Chirasil-Dex-CB).
Triethyl borane (1.0 equiv) was added.
BF3 (1.0 equiv) was added.