Methylenecyclopropane

Methylenecyclopropane is an organic compound with the formula (CH2)2C\dCH2. It is a hydrocarbon which, as the name suggests, is derived from the addition of a methylene (\dCH2) substituent to a cyclopropane ring. It is a colourless, easily condensed gas that is used as a reagent in organic synthesis.

Synthesis
Methylenecyclopropane can be synthesized via an intramolecular cyclisation reaction from methallyl chloride by treatment with a strong base such sodium amide—sodium tert-butoxide (yield 43%) or sodium bis(trimethylsilyl)amide with further treatment by sodium tert-butoxide (yield 72%). Sodium tert-butoxide is used to isomerize byproduct 1-methylcyclopropene into methylenecyclopropane.


 * [[Image:Methylenecyclopropane prepn.png|311x311px]]

Reactions
Being a strained and unsaturated molecule methylenecyclopropane undergoes many reactions, especially in the presence of metal catalysts. For example, methylenecyclopropanes can be converted to cyclobutenes in the presence of a Platinum catalyst. This can be considered similar to the ring expansion seen in vinylcyclopropane rearrangements


 * [[Image:MethylenecyclopropaneIsomerization.png|600px|Methylene cyclopropane isomerization]]

Substituted methylenecyclopropanes can also be involved in trimethylenemethane cycloaddition reactions.