Table 7.
Enantioselective reduction of other heterocyclic ketones using spiroborates 3 and 5 as catalysts
 | ||||||
|---|---|---|---|---|---|---|
| Entry | Substrate | Cat. | Prod | Mol % | Yield (%) | eea (%) |
| 1 | 5-acetyl-2-methoxy pyridine | 5 | 11 | 1 | 77 | 98b |
| 2 | 2-acetylphenothiazine | 5 | 12 | 1 | 94 | 94 |
| 3 | 2-acetylphenothiazine | 5 | 12 | 10 | 97 | >99 |
| 4 | 2-acetylphenothiazine | 3 | 12 | 10 | 95 | >99 |
| 5 | 4′-(Imidazol-1-yl) acetophenone) | 5 | 13 | 1 | 85 | 90 |
| 6 | 4′-(Imidazol-1-yl) acetophenone | 5 | 13 | 10 | 76 | 92 |
| 7 | 3-benzoylpyridine | 5 | 14 | 10 | 83 | 83 |
a
By 31P NMR of phosphonate (CDA) derivative.14
b
By GC of O-acetyl derivatives on a chiral column.