A novel method for the synthesis of substituted naphthalenes and phenanthrenes

Heating of o-allyl-substituted acylbenzenes with potassium tert-butoxide in DMF with simultaneous irradiation from a high-pressure mercury lamp afforded substituted naphthalenes, including arylnaphthalenes. 2-(o-Tolyl)-substituted aromatic aldehydes were converted into phenanthrenes under the same conditions. A formal synthesis of tanshinone I has also been achieved.