Irradiation of an acetonitrile-water solution containing 2-alkoxynaphthalene, an amine, and m-dicyanobenzene gave selectively 2-alkoxy-1-alkylamino-1,4-dihydronaphthalenes in relatively good yields. The aminodihydronaphthalenes were acetylated with Ac2O and then treated with BF3·OEt2 to give N-acetyl-1-alkylamino-2-tetralones in good yields.
Photoaminations of 2-alkoxynaphthalenes (1) with ammonia and primary alkylamines were performed by irradiating an acetonitrile–water solution containing 1, an amine, and m-dicyanobenzene to give 1-alkylamino-2-alkoxy-1,4-dihydronaphthalene (2) in relatively good yields. The conversion of 2 to N-acetyl-1-alkylamino-2-tetralones was performed by acetylation with Ac2O followed by a treatment with BF3·OEt2