Synthesis and applications of main-group organometallics: Studies on C-H borylation and [1.1.1]propellane-derived bicycloalkyls

Abstract: We have identified that dipyridylarylmethane ligand-supported iridium complexes are highly active catalysts for the C-H borylation of unactivated alkanes to give alkylboronate esters. Our studies show that a series of isolable iridium hydridoboryls serve as the resting state species during catalysis and function as excellent single-source precatalysts. We have applied the products of alkane C-H borylation as nucleophilic coupling partners in Pd-catalyzed cross-coupling methods. Alongside this work, we have been developing methods for the introduction of the bicyclo[1.1.1]pentyl (bcp) fragment in organic molecules via the intermediacy of main group derivatives. We have introduced phosphines bearing this substituent including the PtBu3 relative tris(bicyclo[1.1.1]pentyl)phosphine (PBcp3) which can be synthesized by radical alkylation of PH3 with 1.1.1-propellane. This approach is extended to organoaluminum chemistry to give bicyclo[1.1.1]pentyl alanes which can be applied in Pd-catalyzed cross-coupling methods.