Low temperature Kumada–Corriu cross-coupling of polychlorinated acene derivatives and a synthesis of sterically demanding acenes

Conditions for low-temperature Kumada–Corriu cross-coupling of polychlorinated acenes with Grignard reagents are reported. Our work was motivated by a search for cross-coupling reactions effective in the synthesis of functionalized linear acenes for organic materials applications. Treatment of polychlorinated acenes with the PEPPSI-IPr catalyst and MeMgBr undergo 6–8 concurrent coupling reactions to yield products such as octamethylnaphthalene, which is distorted out of planarity due to the steric interaction between the methyl groups. More sterically demanding Grignard reagents such as PhMgBr coupled cleanly with 9,10-dichloroanthracene to provide products such as 9,10-diphenylanthracene, a blue OLED component, in excellent yield.