While the synthesis of biaryls has advanced rapidly in the past decades, cross-Ullman couplings of aryl chlorides, the most abundant aryl electrophiles, have remained elusive. Reported here is the first general cross-Ullman coupling of aryl chlorides with aryl triflates. The selectivity challenge associated with coupling an inert electrophile with a reactive one is overcome using a multimetallic strategy with the appropriate choice of additive. Studies demonstrate that LiCl is essential for effective cross-coupling by accelerating the reduction of Ni(II) to Ni(0) and counteracting autoinhibition of reduction at Zn(0) by Zn(II) salts. The modified conditions tolerate a variety of functional groups on either coupling partner (42 examples), and examples include a three-step synthesis of flurbiprofen.

Versatile directed aromatic C–H bond activation and oxidative coupling with allylic alcohols is reported using a cationic Rh(III) catalyst. This method provides efficient and robust synthesis of functional β-aryl ketones and indolines in good yields with excellent regioselectivity, even the reaction runs at 3 g scale. The catalytic systems have good functional group tolerance, such as CONR₂, NHAc, NO₂, CF₃, CN, Cl, Br and I.