Table 3.
Reduction of β-keto phosphonate
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|---|---|---|---|---|
| Entry | Hydride | Conditions | Yield (%) | Ratio (a:b)a |
| 1 | NaBH4 | EtOH, 0 °C | 75 | 1:2.5 |
| 2 | NaBH4, CeCl3 | EtOH, −78 °C | 82 | 1:1 |
| 3 | NaBH4, CeCl3 | EtOH, 0 °C | 85 | 1:1 |
| 4 | NaBH4, MgCl2 | EtOH, 0 °C | 60 | 1:1 |
| 5 | Li(C2H5)3BH | THF, 0 °C | 33 | 1:9 |
| 6 | LiAl[OC(C2H5)3]3H | THF, 0 °C | 40 | 1:11 |
| 7 | Catecholborane | THF, 0 °C | NRb | NR |
a refers to the diastereomer that elutes first, b refers to the diastereomer that elutes second.
NR, no reaction.
