Table 1 Optimization of the reaction conditions for Rh-catalyzed asymmetric conjugate addition
entry | variations from condition Aa | conv. (%)b | 4aa/5aab | yield (%)c 4aa | % eed 4aa |
---|---|---|---|---|---|
1 | none | > 99 | > 50:1 | 94 | 99 |
2 | (R)-segphos | 52 | > 50:1 | 46 | 12 |
3 | (R)-difluorphos | > 99 | > 50:1 | 88 | 50 |
4 | (R)-binap | > 99 | > 50:1 | 86 | 40 |
5 | (R)-DM-binap | 70 | 72:28 | 49 | 59 |
6 | (R)-DTBM-binap | > 99 | 59:41 | 53 | 99 |
7 | (S,S)-Fc-tfb | < 3 | – | 0 | – |
8 | without ClSiMe3 | < 3 | – | 0 | – |
9 | at 30 °C | > 99 | > 50:1 | 90 | 93 |