Palladium-catalysed cross coupling of arylboronic acids with 2-chloro-1,4-naphthoquinones: the synthesis of 2-aryl- and 2,3-bisaryl-1,4-naphthoquinones

2-Chloro-1,4-naphthoquinones underwent palladium-catalysed cross coupling reactions with arylboronic acids to give the corresponding 2-aryl-1,4-naphthoquinones. Similarly, 2,3-dichloro-1,4-naphthoquinone underwent efficient cross coupling reactions with arylboronic acids to give mono or bis adducts. The required 2-chloro-1,4-naphthoquinones were conveniently prepared from the corresponding 2-hydroxy-1,4-naphthoquinones by treatment with oxalyl chloride.