Methylenecyclopropenes oxidation

Oxidative activation of cyclopropenes is much less frequently encountered. The reactions of various platinum(O) complexes with the electron-deficient methylenecyclopropene 170 affords platinacyclobutene complexes, as reported nearly 30 years ago <1978ICA19>. More recent investigation has established that in the presence of two or more equivalents of the metal, bicyclic diplatinum complexes can be generated (Scheme 40) <1996JBS75>. 

There is one substituted methylenecyclopropene for which the radical cation is well understood the 2,3-diphenyl, 4-hydroxy, 4-methoxy derivative (16). This ion is not formed by 1-electron oxidation or chemi-ionization from the methylenecyclopropene. Instead it arises from rearrangement of its tautomer, methyl 2,3-diphenylcyclopropene-l-carboxylate (17) in pro tic media . This represents another example of reversal of stability... 

Although the oxidation chemistry of methylenecyclopropenes is not well developed, a... 

The reaction of cyclopropenones (16) with compounds containing active methylene groups leads to methylenecyclopropenes (17), which on oxidation give a new family of alkylidenequinocyclopropanes (18). These are highly coloured. 

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