Iridium‐Catalyzed C(sp³)−H Borylation Using Silyl‐Bipyridine Pincer Ligands

Abstract

Abstract New ligands for the iridium‐catalyzed C(sp 3 )−H borylation of aliphatic compounds were established. In sharp contrast to 6‐methyl‐2,2′‐bipyridine and 6‐isobutyl‐2,2′‐bipyridine, 2,2′‐bipyridine and 1,10‐phenanthroline derivatives bearing a hydrosilylmethyl group (which would give a thermally stable NNSi pincer complex) served as suitable ligands for the reaction. Among them, a phenanthroline‐based NNSi pincer ligand was shown to be an excellent ligand, and various aliphatic compounds were efficiently converted to the corresponding borylated products using the Ir/NNSi pincer catalyst system. The NNSi pincer ligand showed unique selectivity and enabled the iridium‐catalyzed C(sp 3 )−H borylation using pinacolborane [H−B(pin)] instead of B 2 (pin) 2 . The formation of an iridium complex bearing a quinoline‐based NNSi pincer ligand from [IrCl(cod)] 2 was observed, and the catalytic activity of the complex was demonstrated.