Lewis Acid Promoted Homodimerization of Styrene Diols: An Efficient Approach toward 2-Phenylnaphthalenes

We report a straightforward, metal-free, efficient protocol for the synthesis of 2-phenylnaphthalenes from 1-phenylethane-1,2-diols under mild conditions. In this strategy, 1,1,1,3,3,3-hexafluoro-2-propanol is used as a solvent that stabilizes the reaction intermediate. An in situ IR experiment revealed that the reaction proceeds through the formation of phenylacetaldehyde followed by a [4+2] Diels-Alder reaction. Several control experiments were performed to gain mechanistic insights into the reaction.