The Di-n-methane Rearrangement and Related Processes

The barrelene (72a) undergoes efficient photorearrangement to the semibullvalene (73a). The reaction is best carried out in cyclohexane with 254 nm radiation. The yield of product (73a) is 94yo and the isomeric barrelene (72b) is 

A detailed review of the family of reactions related to and including the di-7i-methane rearrangement has been published.  

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