Cyclopropanation of cycloalkenes

Cyclopropanation of cycloalkenes by this procedure also produced the least sterically hindered bicyclic compound. For example, the copper-catalysed addition of ethyl diazoacetate onto cyclohexene afforded 69% of the exo (111) and 4% of the endo compound (111a) (equation 26). Next to the traditional Cu catalysts, homogeneous... 

Similarly, cyclopropanation of cycloalkenes and regioselective opening of the three-membered ring can be used in ring-expansion procedures. In the presence of a catalytic amount of bis(acrylonitrile)nickel(0), bicyclo[2.1.0]pentane reacts under mild conditions (40-60 C) with various electron-deficient alkenes, such as methyl acrylate, acrylonitrile, dimethyl maleate and fumarate to give bicyclo[2.2.1]heptane derivatives. An analogous thermal reaction of bicyclo[2.1.0]pentane with, e.g. fumaronitrile, requires much higher temperatures (160°C). ... 

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