Construction of the Cyclopropane Moiety from Activated Olefins and Nucleophiles

2 Construction of the Cyclopropane Moiety from Activated Olefins and Nucleophiles 

The principles of reaction schemes 9, 10, 109, 111 mentioned before, can of course be extended to other synthetic problems. Addition of carbanions 255, bearing a leaving group, across activated olefins and concomitantly cyclizing 1,3-elimination is a very useful approach to obtain trans-isomeric pyrethroid acids (Reaction scheme 158). 

A = activating group (CN.COOR tc.) X s leaving group R AAik Ar,H 

On the other hand, the activated olefin 236 may bear in the allylic position a leaving group thus allowing the deployment of any stronger nucleophile for 

According to scheme 158 the following esters were prepared (Reaction scheme 160)  

---