C(sp 3 )-H activation-enabled cross-coupling of two aryl halides: an approach to 9,10-dihydrophenanthrenes.

A palladium-catalyzed cross-coupling reaction of aryl halides with 2-chlorobenzoic acids has been developed. The reaction forms C(sp3), C(sp2)-palladacycles through C(sp3)-H activation. The palladacycles react with 2-chlorobenzoic acids through two successive C-C cross-couplings, and two C-C bonds are formed with high chemoselectivity. The reaction provides an innovative method for the synthesis of 9,10-dihydrophenanthrenes.