Nucleofugality, structural effects

It is possible to determine the effects of substituents on the regiochemistry of the SnAt reaction in the case of monosubstituted derivatives of pentafluorobenzene because there are now nucleofugal groups in the ortho, meta, and para positions. In molecules with the structure CeFsX, for example, the NH2 group is found to be a deactivating, meta director in SNAr reactions. For a discussion and leading references, see reference 189. 

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