2- -1 - arene- 1 -halo-1 -alkene

Regio- and stereo-selective synthesis of annulated arene heterocycles and carbocy-cles having a halo functionality is accomplished by Sm(OTf)3-catalysed alkylation of (S) arenes by a tethered alkene group using /V-halosuccinimide as a halogen source [e.g. 

All of these carbenes are reactive intermediates that must be generated from the appropriate precursors in the presence of the alkene (or arene) which is to be cyclopropanated. The following methods of carbene-transfer reactions to C-C double bonds will be discussed path a. from a-halo-a-metal (or alkylmetal) compounds by a-elimination path b. from iodine or sulfur ylides by thermal, photochemical or transition metal catalyzed decomposition ... 

---