What reactants should I use to get from 1,5-diphenylpentan-3-one to ((1E,3E)-penta-1,3-diene-1,5-diyl)dibenzene (picture for reference)? Either in 1 step or in multiple steps. I have tried $\ce{NaBH4}$ in acid, then $\ce{POCl3}$ in pyridine, but that only gives one double bond. Is there a way to get both double bonds ?

Reaction of 1,5-diphenylpentan-3-one to ((1E,3E)-penta-1,3-diene-1,5-diyl)dibenzene, no reactants specified.


1 Answer 1


This can be done (on paper) by alpha-selenation of the starting ketone followed by selenoxide elimination to form the alkene (Wikipedia).

The product from this can be reduced by Luche reduction ($\ce{NaBH4/CeCl3}$) to the allylic alcohol.

Finally this can undergo acid catalysed dehydration (PTSA/toluene Dean-Stark reflux) to give the diene.


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