Table 2.
Entry | 1 | Nu-SiMe3 | Product | Yield (%) |
---|---|---|---|---|
1 b | 15 (1.2:1) c | |||
2 | 56 d | |||
3 b | 2a | 25 (1:1.2) c | ||
4 | 40 d | |||
5 | 2a | 52 d | ||
6 | 2a | 46 d | ||
7 | 39 d | |||
8 | 2b | 37 | ||
9 | 1c | 2b | 29 d | |
10 | 1d | 2b | 25 (8:1) c | |
11 | 1a | 34 d | ||
12 | 1b | 2c | 21 | |
13 | 1d | 2c | 29 (7:1) c | |
14 | 1b | 27 |
a Reaction was initiated at −80 °C in the presence of 1 (0.32 mmol), PhI(OAc)2 (0.40 mmol), acetic acid (0.5 mmol) and BF3·OEt2 (0.8 mmol) in CH2Cl2 (4 mL). Then, 2 (1.5 mmol) was added at −40 °C and the reaction mixture was quenched at −30 °C by the addition of water; b The reaction was quenched after warming to rt; c The value in parentheses is the diastereomeric ratio of 3 and 3′ (); d Diastereomer was not detected by 1H-NMR.