反应详情

2 g of O-isopropyl-N,N'-diisopropyl-isourea were added to a mixture of 2.7 g of the product of Step A and 10 ml of ethyl acetate and the mixture was stirred at room temperature for one hour, refluxed for 90 minutes and then cooled to 20° C. The mixture was filtered and the filtrate was evaporated to dryness under reduced pressure. The 3.5 g of oil residue were chromatographed over silica gel and eluted with a 7-3 benzene-cyclohexane mixture to obtain 1 g of tert.-butyl (1R,cis) 2,2-dimethyl-3-[Z-2-(isopropoxycarbonyl)-ethenyl]-cyclopropane-carboxylate which was used as is for the next step.

1. temperaturerefluxed for 90 minutes
2. temperaturecooled to 20° C
3. filtrationThe mixture was filtered
4. customthe filtrate was evaporated to dryness under reduced pressure
5. customThe 3.5 g of oil residue were chromatographed over silica gel
6. washeluted with a 7-3 benzene-cyclohexane mixture