The Trityl‐Cation Mediated Phosphine Oxides Reduction

Abstract

Reduction of phosphine oxides into the corresponding phosphines using PhSiH3 as a reducing agent and Ph3C+[B(C6F5)4]− as an initiator is described. The process is highly efficient, reducing a broad range of secondary and tertiary alkyl and arylphosphines, bearing various functional groups in generally good yields. The reaction is believed to proceed through the generation of a silyl cation, which reaction with the phosphine oxide provides a phosphonium salt, further reduced by the silane to afford the desired phosphine along with siloxanes.

A rare example of the in situ formation of palladium nanoparticles: The emergence of catalytically active palladium nanoparticles from Pd (II) phosphine complexes in the Suzuki–Miyaura coupling reaction

“…This result indicates that phosphorus species in the reaction medium precipitate together with dark/black solid. In order to examine whether these phosphorus species can be phosphine oxides, the oxide form of 1c ( 1c′ ) was synthesized according to literature method [37] and reacted with both Pd (II) (K 2 PdCl 4 ) and Pd(0) species (reduced with NaBH 4 ) in EtOH/H 2 O mixture at room temperature. The 31 P NMR analyses of the reaction medium of these experiments have revealed that the peak of phosphine oxide in 31 P NMR spectrum remained with very strong peak intensity (Figure S23).…”

Low-Field Flow 31P NMR Spectroscopy for Organometallic Chemistry: On-Line Analysis of Highly Air-Sensitive Rhodium Diphosphine Complexes

“… BINAP is well suited for this purpose as it is moderately prone to oxidation and readily replaces the diolefin at room temperature. After recording the 31 P NMR spectrum of the free ( R )-BINAP ( 31 P­{ 1 H} NMR in toluene: δ −15.0 ppm) during the first loop, the dinuclear mono-substituted species [(COD)­Rh­(μ-Cl) 2 Rh­(( R )-BINAP)] ( 31 P­{ 1 H} NMR in toluene: δ 50.0 ppm, J RhP = 199.0 Hz) is formed upon addition of the precursor [Rh­(COD)­(μ-Cl)] 2 in a 1:1 ratio (Figure ). The second equivalent of BINAP was added during the third loop, resulting in the formation of the dinuclear, disubstituted species [Rh­(( R )-BINAP)­(μ-Cl)] 2 ( 31 P­{ 1 H} NMR in toluene: δ 49.0 ppm, J RhP = 195.6 Hz). , Due to the undesired oxidation, both complexes disappeared over time, in favor of the mono- and dioxidized BINAP ( 31 P­{ 1 H} NMR in toluene: δ 26.3, −14.7 ppm for mono-oxidized BINAP; δ 27.6 ppm for dioxidized BINAP) …”

“…High-field (HF) 31 P NMR spectroscopy is nowadays considered a routine tool for the characterization of a wide range of phosphorus-containing systems, e.g., inorganic, main group, and organometallic complexes, which could be highly air-and moisture-sensitive or only stable in solution for a limited period. Phosphines are powerful ligands in homogeneous catalysis, and many modern developments rely on the use of plentiful variations of these compounds.…”

“…Phosphines are powerful ligands in homogeneous catalysis, and many modern developments rely on the use of plentiful variations of these compounds. 1 Thus, 31 P NMR spectroscopy has proved to be invaluable for reaction monitoring, allowing direct observation of the activated, active, and deactivated catalyst species, or acquiring kinetic data of stoichiometric transformations. 2 Although being a wellestablished technique, performing such NMR monitoring experiments in a meaningful way is operationally not trivial, as reaction conditions are not always compatible with the requirements of the NMR analysis (e.g., concentration, type of solvent, T 1 relaxation time).…”

Aggregation-induced polarization (AIP) of derivatives of BINOL and BINAP

“…We started this project by taking advantage of GAP chemistry [29][30][31][32][33] and derivatives of BINAP and BINOLs, which are probably the most widely used chiral categories in asymmetric synthesis and catalysis. The selection of the simplest GAP group is based on two factors: (1) it is more likely to form chiral aggregates in solutions in THF and water; (2) they are readily available and concise to synthesize.…”