Ring closing metathesis Chauvin mechanism

Scheme 1 Chauvin mechanism for ring-closing metathesis [4]...

A very interesting catalytic reaction is metathesis, where alkylidenes are exchanged between alkenes. In the classic Chauvin mechanism, an aUgrlidene fragment is cleaved from the alkene substrate and transferred to the metal via the process of equation 24, which requires a metal carbene as catalyst. This has been applied to ring-closing reactions like equation 27 and polymerizations like equation 28. 

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