Tris(pentafluorophenyl)borane-catalyzed Hydride Transfer Reactions in Polysiloxane Chemistry-Piers-Rubinsztajn Reaction and Related Processes

Tris(pentafluorophenyl)borane (TPFPB) is a unique Lewis acid that catalyzes the condensation between hydrosilanes (Si-H) and alkoxysilanes (Si-OR), leading to the formation of siloxane bonds (Si-OSi) with the release of hydrocarbon (R-H) as a byproduct-the so-called Piers-Rubinsztajn reaction. The analogous reactions of hydrosilanes with silanols (Si-OH), alcohols (R-OH), ethers (R-OR') or water in the presence of TPFPB leads to the formation of a siloxane bond, alkoxysilane (Si-OR or Si-OR') or silanol (Si-OH), respectively. The above processes, often referred to as Piers-Rubinsztajn reactions, provide new synthetic tools for the controlled synthesis of siloxane materials under mild conditions with high yields. The common feature of these reactions is the TPFPB-mediated hydride transfer from silicon to carbon or hydrogen. This review presents a summary of 20 years of research efforts related to this field, with a focus on new synthetic methodologies leading to numerous previously difficult to synthesize well-defined siloxane oligomers, polymers and copolymers of a complex structure and potential applications of these new materials. In addition, the mechanistic aspects of the recently discovered reactions involving hydride transfer from silicon to silicon are discussed in more detail.

Automated summary

Tris(pentafluorophenyl)borane (TPFPB) is a unique Lewis acid that enables the condensation between hydrosilanes (Si-H) and alkoxysilanes (Si-OR) to form siloxane bonds (Si-OSi) in the presence of TPFPB, resulting in the release of hydrocarbon (R-H) as a byproduct, known as the Piers-Rubinsztajn reaction. TPFPB also catalyzes reactions involving hydrosilanes with silanols (Si-OH), alcohols (R-OH), ethers (R-OR') or water to form siloxane bonds, alkoxysilane (Si-OR or Si-OR') or silanol (Si-OH), respectively. These Piers-Rubinsztajn reactions provide new synthetic tools for the controlled synthesis of siloxane materials under mild conditions with high yields. This review summarizes 20 years of research efforts in this field, highlights new synthetic methodologies for well-defined siloxane oligomers, polymers, and copolymers, and discusses the potential applications of these new materials. Furthermore, the mechanistic aspects of recently discovered reactions involving hydride transfer from silicon to silicon are also discussed in detail.