Table 47.
Comparison of the asymmetric hydrogenation of ethyl acetoacetate with SEGPhos and SEGPhos' in ethanol solvent and under solvent-free conditions.
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entry | solvent | additive | L* | conversion (%) | ee (%) |
1 | EtOH | none | SEGPhos′ | 35.9 | 96.0 |
2 | EtOH | none | SEGPhos | 35.7 | 96.6 |
3 | none | none | SEGPhos′ | 56.8 | 91.6 |
4 | none | none | SEGPhos | 62.5 | 88.4 |
5a | none | H2SO4 | SEGPhos′ | 100 | 96.8 |
6b | none | H2SO4 | SEGPhos | 100 | 97.5 |
All reactions were carried out with a ratio of 20,000:1 (substrate/catalyst).
Additive : Ru = 1.5:1.