Table 1.
Optimization of the Iodocyclopropanation to Form 1a in Scheme 4 by Screening Zinc Carbenoids and Reaction Conditions.
| entry | carbenoid | equiv | T (°C) | dr | yield (%)a | comment |
|---|---|---|---|---|---|---|
| 1 | EtZnCHI2 | 5 | 20 | >20:1 | nd | low conversionb |
| 2 | IZnCHI2 | 5 | 20 | >20:1 | nd | low conversionb |
| 3 | CF3CO2ZnCHI2 | 2 | 20 | ~3:1 | 18 | many products |
| 4 | CF3CO2ZnCHI2 | 2 | 0 | ~10:1 | 25 | |
| 5 | CF3CH2OZnCHI2 | 2 | 20 | >20:1 | 30 | |
| 6 | CF3CH2OZnCHI2 | 5 | 0 | >20:1 | nd | low conversionb |
| 7 | CF3CH2OZnCHI2 | 2 | 20 | >20:1 | 66 | 4 Å MS added |
a
After 24 h.
b
Some allylic alcohol was recovered in these runs.