Table 2.
Entry | R1 | R3 | Product | % Yield | d.r. |
---|---|---|---|---|---|
1 | Me | Ph | 2a | 70 | ≥97:3 |
2 | Ph | Me | 2f | 62 | ≥97:3 |
3 | Ph | n-Bu | 2g | 72 | ≥97:3 |
4 | Ph | CH2OTBDMS | 2h | 71 | ≥97:3 |
5 | Et | (CH2)2OBn | 2i | 75 | ≥97:3 |
Conditions: α-keto ester (1.0 equiv), silacyclopropane 2 (1.5 equiv), AgOTs (0.10 equiv), toluene, −25 °C, 16 h then, HF·Pyr (4.0 equiv), isolated yields.