Table 26.
| |||||
---|---|---|---|---|---|
entry | R1 | R2 | R3 | R4 | yield (dr)a,b |
1 | Ph | H | Ph | p-AcOC6H4 | 53 (>19:1) |
2 | Ph | H | Ph | Ph | 54 (10:1) |
3 | H | H | H | p-AcOC6H4 | 99 (1:2.8) |
4 | H | H | H | Ph | 85 (1:3) |
5 | H | CH3 | H | p-AcOC6H4 | 92 (1:2) |
6 | H | CH3 | H | Ph | 99 (1:2) |
7 | H | Ph | H | Ph | 87 (1:>19) |
Yield and syn/anti ratio of isolated product.
>19:1 indicates that the minor diastereomer was not detected by 1H NMR spectroscopy.