Palladium-Catalyzed Selective Synthesis of Naphthalenes and Indenones and Their Luminescent Properties - Chen - 2011 - European Journal of Organic Chemistry - Wiley Online Library

Selective synthesis of functionalized naphthalenes and indenones by palladium-catalyzed cyclization of o-haloacetophenones and terminal alkynes in the presence of a secondary amine is reported. Under a nitrogen atmosphere, the palladium-catalyzed reaction of o-haloacetophenones with terminal alkynes in the presence of wet secondary aminesgenerated 1-(dialkylamino)-3-aryl/alkylnaphthalenes. When the reaction was conducted in air, 1-indenone-3-carbaldehydes were obtained. The synthesized β-arylnaphthalenes 4a–f emit light in a range from 386 to 452 nm with quantum yields from 0.10 to 0.48 in cyclohexane. The absorption and emission efficiency of 4d were finely tuned by the acidity of the environment, and this might be useful in the use of 4d as a fluorescent pH sensor.