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

Abstract

AbstractC−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 31P 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 1JP=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.magnified image