Arylethanals acid treatment

Acid treatment of arylethanals may lead to 2-phenylnaphthalenes or l,2,9,10-tetrahydro-l,9-epoxydibenzo[a,e]cyclooctenes (Kagan s ether). 2-Phenylnaphthalenes were obtained by a C-condensation of the enolated form on the keto form. The resulting aldol condensation product underwent an intramolecular reaction to give, after rearomatisation, the 2-phenylnaphthalenes, Fig. (1). 

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