Cyclopropyl carbene complexes reactions with alkenes

Simple alkenes, norbomene and styrene do not undergo cyclopropanation or insertion reactions with cyclopropyl(methoxy)carbene chromium pentacarbonyl complex. However, the conjugated 1-vinylcyclopentene is cyclopropanated under the reaction conditions at the terminal double bond, affording an isomeric mixture (trans cis = 40 60), in 66% yield (equation 72). 

The reaction of the chromium complex of cyclopropyl(methoxy)carbene with an alkene results in the formation of bicyclopropyl derivatives 4 in good yield, accompanied occasionally by minor amounts of ring-opened products. 

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