Phosphorus-Directed Rhodium-Catalyzed C-H Arylation of 1-Pyrenylphosphines Selective at the K-Region

C-H arylation of 1-pyrenylphosphine derivatives catalyzed by rhodium and directed by a diphenylphosphino group is selectively achieved at the K-region, i. e. 4-, 5-, 9-, or 10-position of the pyrene moiety. This peri C-H activation/arylation of pyrenes using (hetero)aryl bromide coupling partners tolerates both electron-donating and electron-withdrawing groups on the arene, and provides isolated yields of products between 25% to 90%, including from bulky polyaromatic bromoarene substrates. We achieved investigations directed at the formation and reactivity of pertinent intermediate species in this C-H arylation reaction. The P-ligand coordination at rhodium was established using P-31 NMR and XRD analysis, and we isolated five-membered rhodacycles as intermediates to the directed C-H functionalization. The data obtained overall supported the occurrence of a cationic rhodium catalytic process. We further described the access to a large class of pyrenylphosphine ligands and their selenated derivatives. Phosphine selenation allows to rapidly estimate from (1)J(P=Se) values the basic character of the ligand in the perspective of their use for coordination. Accordingly, linear P-coordinated Au(I) gold complexes were isolated, in addition to the variously coordinated Rh(III) complexes. The present methodology significantly extends the scope of polyaromatics that are functionalizable at the K-Region by direct C-H activation, beyond smaller-sized naphtalenes and aminopyrenes.