Preparation of phosphines through C-P bond formation

Palladium-catalyzed coupling of aryl sulfonium salts with [TBA][P(SiCl3)2] for the construction of tertiary phosphines

We present a strategy for the synthesis of triarylphosphines via palladium-catalyzed C-P cross-coupling reactions of aryl sulfonium salts with [TBA][P(SiCl3)2]. This method utilizes [TBA][P(SiCl3)2], a phosphorus derivative of phosphoric acid, as the phosphorus source. This approach circumvents the hazards and intricate pathways associated with white phosphorus.

Copper-Mediated Phosphoniumation of Aryl/Vinyl Boronic Acids

Following the successful construction of nitrilium/pyridinium and sulfonium salts, the Chan-Lam coupling has been significantly advanced with the first demonstration of quaternary phosphonium salt synthesis. We present a method employing copper(II) acetate in trifluoroethanol to efficiently produce a range of aryl and vinyl phosphonium salts from boronic acids, including those derived from complex natural products, thus overcoming phosphine oxidation issues and expanding the scope to functionalized phosphorus.

Cross-Electrophile Coupling: Principles, Methods, and Applications in Synthesis

Cross-electrophile coupling (XEC), defined by us as the cross-coupling of two different σ-electrophiles that is driven by catalyst reduction, has seen rapid progression in recent years. As such, this review aims to summarize the field from its beginnings up until mid-2023 and to provide comprehensive coverage on synthetic methods and current state of mechanistic understanding. Chapters are split by type of bond formed, which include C(sp3)-C(sp3), C(sp2)-C(sp2), C(sp2)-C(sp3), and C(sp2)-C(sp) bond formation. Additional chapters include alkene difunctionalization, alkyne difunctionalization, and formation of carbon-heteroatom bonds. Each chapter is generally organized with an initial summary of mechanisms followed by detailed figures and notes on methodological developments and ending with application notes in synthesis. While XEC is becoming an increasingly utilized approach in synthesis, its early stage of development means that optimal catalysts, ligands, additives, and reductants are still in flux. This review has collected data on these and various other aspects of the reactions to capture the state of the field. Finally, the data collected on the papers in this review is offered as Supporting Information for readers.

Selective Functionalization of White Phosphorus with Alkyl Bromides under Photocatalytic Conditions: A Chlorine-Free Protocol to Dialkyl and Trialkyl Phosphine Oxides

A novel and efficient method for the direct selective alkylation of white phosphorus (P4) with alkyl bromides has been developed, utilizing 4DPAIPN as the photocatalyst and Hantzsch ester as the reductant. This method facilitates the synthesis of structurally diverse dialkyl phosphine oxides in good yields, offering a streamlined alternative to the traditional stepwise approach of chlorinating P4 with Cl2 and subsequently displacing the chlorine atom. Noteworthy features of this reaction include excellent product selectivity, remarkable functional group tolerance, and a broad substrate scope. Additionally, this method is effective for the synthesis of trialkyl phosphine oxides.

Photoinduced, Redox-Neutral Decyanative and Defluorinative Phosphination of (Hetero)Arenes

Triarylphosphines play a crucial role in organic synthesis as versatile components serving as ligands, catalysts, and reactants. This study introduces a metal-free, visible-light-induced method for the cross-coupling of cyanopyridines or polyfluoroarenes with diarylphosphines. This approach facilitates the formation of C(sp2)-P bonds through redox-neutral decyanative or defluorinative process, enabling the convenient synthesis of diverse triarylphosphines.

Base-Promoted Nucleophilic Phosphorylation of Benzyl Fluorides via C(sp3)-F Cleavage

Herein, a transition-metal-free phosphorylation of benzyl fluorides with P(O)-H compounds is disclosed. In the presence of tBuOK, various benzyl fluorides react with P(O)-H compounds to produce the corresponding benzyl phosphine oxides, phosphinates, and phosphonates in good to high yields. This base-promoted phosphorylation reaction offers a facile and general strategy for the construction of a C(sp3)-P bond.

Palladium-Catalyzed Asymmetric Desymmetrization for the Simultaneous Construction of Chiral Phosphorus and Quaternary Carbon Stereocenters

A palladium-catalyzed asymmetric tandem Heck and carbonylation of bisallyl-phosphine oxides has been developed. This desymmetrization process provided an efficient route to the simultaneous synthesis of a chiral P-stereogenic center and a chiral quaternary carbon stereocenter in good yields with good diastereo- and enantioselectivities.

Ytterbium(II) Complex-Catalyzed Selective Single and Double Hydrophosphination of 1,3-Enynes

1,3-Enynes with conjugated alkene and alkyne moieties are attractive building blocks in synthetic chemistry. However, neither 4,1-hydrophosphination nor dihydrophosphination of 1,3-enynes has been reported. In this paper, the divalent ytterbium and calcium amide complexes supported by silaimine-functionalized cyclopentadienyl ligands (C5Me4-Si(L)=NR) were developed, which successfully catalyzed the efficient single and double hydrophosphination of 1,3-enynes with diarylphosphines. The hydrophosphination reactions selectively produced homoallenyl phosphines and (E)-propenylene diphosphines, respectively. This work demonstrated the potential of hemilabile silaimine-Cp ligands in the supporting the efficient and selective rare- and alkaline-earth catalysts.

Alpha-metalated N,N-dimethylbenzylamine rare-earth metal complexes and their catalytic applications

This perspective summarizes our group's extensive research in the realm of organometallic lanthanide complexes, while also placing the catalytic reactions supported by these species within the context of known lanthanide catalysis worldwide, with a specific focus on phosphorus-based catalytic reactions such as intermolecular hydrophosphination and hydrophosphinylation. α-Metalated N,N-dimethylbenzylamine ligands have been utilized to generate homoleptic lanthanide complexes, which have subsequently proven to be highly active lanthanum-based catalysts. The main goal of our research program has been to enhance the catalytic efficiency of lanthanum-based complexes, which began with initial successes in the stoichiometric synthesis of organometallic lanthanide complexes and utilization of these species in catalytic hydrophosphination reactions. Not only have these species supported traditional lanthanide catalysis, such as the hydrophosphination of heterocumulenes like carbodiimides, isocyanates, and isothiocyanates, but they have also been effective for a plethora of catalytic reactions tested thus far, including the hydrophosphinylation and hydrophosphorylation of nitriles, hydrophosphination and hydrophosphinylation of alkynes and alkenes, and the heterodehydrocoupling of silanes and amines. Each of these catalytic transformations is meritorious in its own right, offering new synthetic routes to generate organic scaffolds with enhanced functionality while concurrently minimizing both waste generation and energy consumption. Objectives: We aim for the research summary presented herein to inspire and encourage other researchers to investigate f-element based stoichiometric and catalytic reactions. Our efforts in this field began with the recognition that potassium salts of benzyldimethylamine preferred deprotonation at the α-position, rather than the ortho-position, and we wondered if this regiochemistry would be retained in the formation of lanthanide complexes. The pursuit of this simple idea led first to a series of structurally fascinating homoleptic organometallic lanthanide complexes with surprisingly good stability. Fundamental studies of the protonolysis chemistry of these complexes ultimately revealed highly versatile lanthanide-based precatalysts that have propelled a catalytic investigation spanning more than a decade. We anticipate that this summative perspective will animate the synthetic as well as biological communities to consider La(DMBA)3-based catalytic methods in the synthesis of functionalized organic scaffolds as an atom-economic, convenient, and efficient methodology. Ultimately, we envision our work making a positive impact on the advancement of novel chemical transformations and contributing to progress in various fields of science and technology.

Direct Synthesis of Tertiary Phosphines via Alkoxide-Mediated Deborylative Phosphination of Organoboronates

The direct transformation of alkylboron has emerged as a versatile and powerful methodology for creating carbon-carbon and carbon-heteroatom bonds. However, its potential application in the formation of carbon and phosphorus remains unexplored. In this study, we present an alkoxide base-promoted reaction system that enables deborylative phosphination of benzylic organoboronates and geminal bis(boronates) via selective C-B bond cleavage. This approach allows for the synthesis of valuable tertiary phosphines in good yields under mild conditions. The practicality and industrial potential of this approach are underscored by the operational simplicity, broad substrate scope, and easy scalability.

Pd(II)-Catalyzed enantioselective C-H olefination toward the synthesis of P-stereogenic phosphinamides

P-Stereogenic phosphorus compounds are important structural elements in chiral ligands or organocatalysts. Herein, we report a Pd(II)-catalyzed enantioselective C-H olefination toward the synthesis of P-stereogenic phosphinamides using cheap commercially available L-pGlu-OH as a chiral ligand. A broad range of P-stereogenic phosphinamides were gained in good yields with high enantioselectivities (33 examples, up to 77% yield, 99% ee) via desymmetrization and kinetic resolution.

Diphosphine Bioconjugates via Pt(0)-Catalyzed Hydrophosphination. A Versatile Chelator Platform for Technetium-99m and Rhenium-188 Radiolabeling of Biomolecules

The ability to append targeting biomolecules to chelators that efficiently coordinate to the diagnostic imaging radionuclide, 99mTc, and the therapeutic radionuclide, 188Re, can potentially enable receptor-targeted "theranostic" treatment of disease. Here we show that Pt(0)-catalyzed hydrophosphination reactions are well-suited to the derivatization of diphosphines with biomolecular moieties enabling the efficient synthesis of ligands of the type Ph2PCH2CH2P(CH2CH2-Glc)2 (L, where Glc = a glucose moiety) using the readily accessible Ph2PCH2CH2PH2 and acryl derivatives. It is shown that hydrophosphination of an acrylate derivative of a deprotected glucose can be carried out in aqueous media. Furthermore, the resulting glucose-chelator conjugates can be radiolabeled with either 99mTc(V) or 188Re(V) in high radiochemical yields (>95%), to furnish separable mixtures of cis- and trans-[M(O)2L2]+ (M = Tc, Re). Single photon emission computed tomography (SPECT) imaging and ex vivo biodistribution in healthy mice show that each isomer possesses favorable pharmacokinetic properties, with rapid clearance from blood circulation via a renal pathway. Both cis-[99mTc(O)2L2]+ and trans-[99mTc(O)2L2]+ exhibit high stability in serum. This new class of functionalized diphosphine chelators has the potential to provide access to receptor-targeted dual diagnostic/therapeutic pairs of radiopharmaceutical agents, for molecular 99mTc SPECT imaging and 188Re systemic radiotherapy.

Bulky, electron-rich, renewable: analogues of Beller's phosphine for cross-couplings

In recent years, considerable progress has been made in the conversion of biomass into renewable chemicals, yet the range of value-added products that can be formed from biomass remains relatively small. Herein, we demonstrate that molecules available from biomass serve as viable starting materials for the synthesis of phosphine ligands, which can be used in homogeneous catalysis. Specifically, we prepared renewable analogues of Beller's ligand (di(1-adamantyl)-n-butylphosphine, cataCXium® A), which is widely used in homogeneous catalysis. Our new renewable phosphine ligands facilitate Pd-catalysed Suzuki-Miyaura, Stille, and Buchwald-Hartwig coupling reactions with high yields, and our catalytic results can be rationalized based on the stereoelectronic properties of the ligands. The new phosphine ligands generate catalytic systems that can be applied for the late-stage functionalization of commercial drugs.

Cross-Electrophile C-PIII Coupling of Chlorophosphines with Organic Halides: Photoinduced PIII and Aminoalkyl Radical Generation Enabled by Pnictogen Bonding

Pnictogen bonding (PnB) has gained recognition as an appealing strategy for constructing novel architectures and unlocking new properties. Within the synthetic community, the development of a straightforward and much simpler protocol for cross-electrophile C-PIII coupling remains an ongoing challenge with organic halides. In this study, we present a simple strategy for photoinduced PnB-enabled cross-electrophile C-PIII couplings using readily available chlorophosphines and organic halides via merging single electron transfer (SET) and halogen atom transfer (XAT) processes. In this photomediated transformation, the PnB formed between chlorophosphines and alkyl amines facilitates the photogeneration of PIII radicals and α-aminoalkyl radicals through SET. Subsequently, the resulting α-aminoalkyl radicals activate C-X bonds via XAT, leading to the formation of carbon radicals. This methodology offers operational simplicity and compatibility with both aliphatic and aromatic chlorophosphines and organic halides.

Radical Phosphorylation of Aliphatic C-H Bonds via Iron Photocatalysis

The synthesis of tertiary phosphines(III) has been a long-standing challenge in synthetic chemistry because of inevitable issues including harsh conditions, sensitive organometallic reagents, and prefunctionalized substrates in traditional synthesis. Herein, we report a strategically novel C(sp3)-H bond phosphorylation that enables the assembly of structurally diverse tertiary phosphines(III) from industrial phosphine(III) sources under mild photocatalytic conditions. The merger of ligand-to-metal charge transfer (LMCT) of FeCl3 with the hydrogen atom-transfer (HAT) process is the key for the generation of alkyl radicals from hydrocarbons. Strikingly, this catalytic system can be successfully applied for the polymerization of electron-deficient alkenes.

Manganese(I)-Catalyzed Asymmetric Hydrophosphination of α,β-Unsaturated Carbonyl Derivatives

Here we report catalytic asymmetric hydrophosphination of α,β-unsaturated carbonyl derivatives using a chiral Mn(I) complex as a catalyst. Through H-P bond activation, various phosphine-containing chiral products can be accessed via hydrophosphination of various ketone-, ester-, and carboxamide-based Michael acceptors.

Stille type P-C coupling polycondensation towards phosphorus-crosslinked polythiophenes with P-regulated photocatalytic hydrogen evolution

Recently, exploring new type polymerization protocols has been a major driving force in advancing organic polymers into highly functional materials. Herein we report a new polycondensation protocol to implant the phosphorus (P) atom in the main backbone of crosslinked polythiophenes. The polycondensation harnesses a Stille phosphorus-carbon (P-C) coupling reaction between phosphorus halides and aryl stannanes that has not been reported previously. Mechanistic studies uncovered that the P-electrophile makes the reactivity of a catalytic Pd-center highly sensitive towards the chemical structures of aryl stannanes, which is distinct from the typical Stille carbon-carbon coupling reaction. The efficient P-C polycondensation afforded a series of P-crosslinked polythiophenes (PC-PTs). Leveraging on the direct P-crosslinking polymerization, solid-state ³¹P NMR studies revealed highly uniform crosslinking environments. Efficient post-polymerization P-chemistry was also applied to the PC-PTs, which readily yielded the polymers with various P-environments. As a proof of concept, new PC-PTs were applied as the photocatalysts for H₂ evolution under visible light irradiation. PC-PTs with an ionic P(Me)-center exhibit a H₂ evolution rate up to 2050 μmol h^-1 g^-1, which is much higher than those of PC-PTs with a P(O)-center (900 μmol h^-1 g^-1) and P(iii)-center (155 μmol h^-1 g^-1). For the first time, the studies reveal that regulating P-center environments can be an effective strategy for fine tuning the photocatalytic H₂ evolution performance of organic polymers.

Ni-catalyzed C-F activation to construct C-P bond with P-P(O) and P(O)OR mediation

Here we developed an efficient Ni-catalyzed C-F bond phosphorylation of aryl fluorides via the crucial intermediates of P-P(O) and P(O)OR. P-P(O) mediated organophosphorus generation is observed for active aryl fluorides, whereas inactive aryl fluorides can also be activated and phosphorylated via a P(O)OR-mediated pathway, which is barely reported yet. Facile scale-up to the gram level and the upgrading of the bioactive molecule make this protocol to have promising applications in synthetic chemistry.

Broken Promises? On the Continued Challenges Faced in Catalytic Hydrophosphination

In this Perspective, we discuss what we perceive to be the continued challenges faced in catalytic hydrophosphination chemistry. Currently the literature is dominated by catalysts, many of which are highly effective, that generate the same phosphorus architectures, e.g., anti-Markovnikov products from the reaction of activated alkenes and alkynes with diarylphosphines. We highlight the state of the art in stereoselective hydrophosphination and the scope and limitations of chemoselective hydrophosphination with primary phosphines and PH₃. We also highlight the progress in the chemistry of the heavier homologues. In general, we have tried to emphasize what is missing from our hydrophosphination armament, with the aim of guiding future research targets.

Ultramicroporous Organophosphorus Polymers via Self-Accelerating P-C Coupling Reactions: Kinetic Effects on Crosslinking Environments and Porous Structures

Porous organic polymers (POPs) have drawn significant attention in diverse applications. However, factors affecting the heterogeneous polymerization and porosity of POPs are still not well understood. Herein, we report a new strategy to construct porous organophosphorus polymers (POPPs) with high surface areas (1283 m²/g) and ultramicroporous structures (0.67 nm). The strategy harnesses an efficient transition-metal-catalyzed phosphorus-carbon (P-C) coupling reaction at the trigonal pyramidal P-center, which is distinct from the typical carbon-carbon coupling reaction utilized in the synthesis of POPs. As the first kinetic study on the coupling reaction of POPs, we uncovered a self-accelerating reaction characteristic, which is controlled by the choice of bases and catalysts. The self-accelerating characteristic of the P-C coupling reaction is beneficial for the high surface area and uniform ultramicroporosity of POPPs. The direct crosslinking of the P-centers allows ³¹P solid-state (ss)NMR experiments to unambiguously reveal the crosslinking environments of POPPs. Leveraging on the kinetic studies and ³¹P ssNMR studies, we were able to reveal the kinetic effects of the P-C coupling reaction on both the crosslinking environments and the porous structures of POPPs. Furthermore, our studies show that the CO₂ uptake capacity of POPPs is highly dependent on their porous structures. Overall, our studies paves the way to design new POPs with better controlled chemical and ultramicroporous structures, which have potential applications for CO₂ capture and separation.

N-Heterocyclic Carbene-Coordinated M(II) (M = Yb, Sm, Ca) Bisamides: Expanding the Limits of Intermolecular Alkene Hydrophosphination

A series of NHC-stabilized amido compounds (NHC)_nM[N(SiMe₃)₂]₂ (M = Yb(II), Sm(II), Ca(II); n = 1, 2) showed remarkable catalytic efficiency in addition of PhPH₂ and PH₃ to alkenes under mild conditions and low catalyst loading. The effect of σ-donor capacity of NHCs on catalytic activity in hydrophosphination of styrene with PhPH₂ and PH₃ was revealed. For the series of three-coordinate complexes 1-4M, a tendency to increase the catalytic activity with growth of σ-donating strength of the carbene ligand was clearly demonstrated. The complex (NHC)₂Sm[N(SiMe₃)₂]₂ (NHC = 1,3-diisopropyl-2H-imidazole-2-ylidene) (5Sm) proved to be the most efficient catalyst, which enabled hardly realizable transformations such as PhPH₂ addition across internal C═C bonds of norbornene and cis- and trans-stilbenes, providing the highest reaction rate for addition of PH₃ to styrene. Excellent regio- and chemoselectivities of alkylation of PH₃ with styrenes allow for a selective and good-yield synthesis of desired organophosphines─either primary, secondary, or tertiary. Stepwise alkylation of PH₃ with various substituted styrenes can be efficiently applied as an approach to nonsymmetric secondary phosphines. The rate equation of the addition of styrene to PH₃ promoted by 5Sm was found: rate = k[styrene]¹[5Sm]¹.

Homogeneous and Heterogeneous Pd-Catalyzed Selective C-P Activation and Transfer Hydrogenation for "Group-Substitution" Synthesis of Trivalent Phosphines

A "group-substitution" synthesis of trivalent phosphines via a C-P activation of phosphonium salts is reported. The alkyl groups were introduced by alkylation of phosphines to form phosphonium salts. The "de-arylation" of phosphonium salts was achieved by C-P activation and transfer hydrogenation with homogeneous or heterogeneous Pd (0) catalysts. With this method, a series of trivalent phosphines were prepared from commercially available triarylphosphines. A chiral monophosphine ligand could be prepared from BINAP in a "de-phosphination" process.

Ni-catalyzed asymmetric hydrophosphinylation of conjugated enynes and mechanistic studies

The catalytic asymmetric synthesis of P-stereogenic phosphines is an efficient strategy to access structurally diverse chiral phosphines that could serve as organocatalysts and ligands to transition metals and motifs of antiviral drugs. Herein, we describe a Ni catalyzed highly regio and enantioselective hydrophosphinylation reaction of secondary phosphine oxides and enynes. This method afforded a plethora of alkenyl phosphine oxides which could serve as valuable precursors to bidentate ligands. A new type of mechanism was discovered by combined kinetic studies and density functional theory (DFT) calculations, which was opposed to the widely accepted Chalk-Harrod type mechanism. Notably, the alkene moiety which could serve as a directing group by coordinating with the Ni catalyst in the transition state, plays a vital role in determining the reactivity, regio and enantioselectivity.

The stereoselective conversion of epimerized alkoxyl phosphine-borane to P,C, axial-stereogenic tertiary phosphine via cleavage of P-O bond

The P-O bond of epimerized alkoxyl phosphine-borane was cleaved by naphthalene-lithium, to form two diastereomers of P-anions in a ratio of 86 : 14, which was then converted to secondary phosphine-borane via acidification, and to tertiary phosphines with alkyl halides with enhanced 96 : 4 dr. The isolated tertiary phosphine containing hydroxyl (in >99 : 1 dr) was converted to multi-stereogenic tertiary phosphines via O-alkylation with alkylene dihalides.

Phosphorylation of arenes, heteroarenes, alkenes, carbonyls and imines by dehydrogenative cross-coupling of P(O)-H and P(R)-H

Organophosphorous compounds have recently emerged as a powerful class of compounds with widespread applications, such as in bioactive natural products, pharmaceuticals, agrochemicals and organic materials, and as ligands in catalysis. The preparation of these compounds requires synthetic techniques with novel catalytic systems varying from transition metal, photo- and electrochemical catalysis to transformations without metal catalysts. Over the past few decades, the addition of P-H bonds to alkenes, alkynes, arenes, heteroarenes and other unsaturated substrates in hydrophosphination and other related reactions via the above-mentioned catalytic processes has emerged as an atom economical approach to obtain organophosphorus compounds. In most of the catalytic cycles, the P-H bond is cleaved to yield a phosphorus-based radical, which adds onto the unsaturated substrate followed by reduction of the corresponding radical yielding the product.

Palladium/Xiao-Phos-Catalyzed Kinetic Resolution of sec-Phosphine Oxides by P-Benzylation

P-stereogenic tert- and sec-phosphines have wide applications in asymmetric catalysis, materials, and pharmaceutical chemistry, however, their practical synthesis still constitutes a significant challenge. Herein, a successful kinetic resolution of rac-secondary phosphine oxides via the enantioselective P-benzylation process catalyzed by the palladium/Xiao-Phos was designed. Both tert- and sec-phosphine oxides were delivered in good yield and excellent enantiopurity (selectivity factor up to 226.1). The appealing synthetic utilities are further demonstrated by the facile preparation of several valuable P-chiral compounds, precursors of bidentate ligands, as well as transition metal complexes.

Nickel Complexes in C‒P Bond Formation

This review is a comprehensive account of reactions with the participation of nickel complexes that result in the formation of carbon-phosphorus (C‒P) bonds. The catalytic and non-catalytic reactions with the participation of nickel complexes as the catalysts and the reagents are described. The various classes of starting compounds and the products formed are discussed individually. The several putative mechanisms of the nickel catalysed reactions are also included, thereby providing insights into both the synthetic and the mechanistic aspects of this phosphorus chemistry.

Palladium-Catalyzed C-P(III) Bond Formation by Coupling ArBr/ArOTf with Acylphosphines

Palladium-catalyzed C-P bond formation reaction of ArBr/ArOTf using acylphosphines as differential phosphination reagents is reported. The acylphosphines show practicable reactivity with ArBr and ArOTf as the phosphination reagents, though they are inert to the air and moisture. The reaction affords trivalent phosphines directly in good yields with a broad substrate scope and functional group tolerance. This reaction discloses the acylphosphines' capability as new phosphorus sources for the direct synthesis of trivalent phosphines.

Rhodium Complexes in P-C Bond Formation: Key Role of a Hydrido Ligand

Olefin hydrophosphanation is an attractive route for the atom-economical synthesis of functionalized phosphanes. This reaction involves the formation of P-C and H-C bonds. Thus, complexes that contain both hydrido and phosphanido functionalities are of great interest for the development of effective and fast catalysts. Herein, we showcase the excellent activity of one of them, [Rh(Tp)H(PMe₃)(PPh₂)] (1), in the hydrophosphanation of a wide range of olefins. In addition to the required nucleophilicity of the phosphanido moiety to accomplish the P-C bond formation, the key role of the hydride ligand in 1 has been disclosed by both experimental results and DFT calculations. An additional Rh-H···C stabilization in some intermediates or transition states favors the hydrogen transfer reaction from rhodium to carbon to form the H-C bond. Further support for our proposal arises from the poor activity exhibited by the related chloride complex [Rh(Tp)Cl(PMe₃)(PPh₂)] as well as from stoichiometric and kinetic studies.

Versatile Visible-Light-Driven Synthesis of Asymmetrical Phosphines and Phosphonium Salts

Asymmetrically substituted tertiary phosphines and quaternary phosphonium salts are used extensively in applications throughout industry and academia. Despite their significance, classical methods to synthesize such compounds often demand either harsh reaction conditions, prefunctionalization of starting materials, highly sensitive organometallic reagents, or expensive transition-metal catalysts. Mild, practical methods thus remain elusive, despite being of great current interest. Herein, we describe a visible-light-driven method to form these products from secondary and primary phosphines. Using an inexpensive organic photocatalyst and blue-light irradiation, arylphosphines can be both alkylated and arylated using commercially available organohalides. In addition, the same organocatalyst can be used to transform white phosphorus (P4 ) directly into symmetrical aryl phosphines and phosphonium salts in a single reaction step, which has previously only been possible using precious metal catalysis.

Organophosphorus and Iron Catalysis: Good Partners for Hydrometalation of Olefins and Alkynes

The last decades have seen an impressive development of iron complexes involving organophosphorus ligands applied in homogeneous catalyzed hydrometalation of olefins and alkynes. Two main topics will be covered in this JOCSynopsis: (i) an overview of the achievements in the area of iron-catalyzed hydrophosphination and then (ii) hydrosilylation, hydroborylation, and hydromagnesiation reactions promoted by catalysts based on organophosphorus ligands and iron.

Hydrophosphination using [GeCl{N(SiMe3)2}3] as a pre-catalyst

Transformations catalyzed by germanium are scarce, with examples mainly limited to widely catalyzed processes such as polymerisation of lactide and hydroboration of carbonyls. Reported is the first example of hydrophosphination using a germanium pre-catalyst, yielding anti-Markovnikov products when diphenylphosphine is reacted with styrenes or internal alkynes at room temperature.

Synthesis of compounds with C-P-P and C[double bond, length as m-dash]P-P bond systems based on the phospha-Wittig reaction

A reactivity study of a β-diketiminate titanium(iii) phosphanylphosphido complex [^MeNacNacTi(Cl){η²-P(SiMe₃)-PtBu₂}] (1) towards ketones such as benzophenone, 9-fluorenone, acetophenone, cyclopentanone, cyclohexanone and cycloheptanone is reported. The reactions of 1 with aromatic ketones (without α-protons) directly lead to the Ti(iii) complex [^MeNacNacTi(μ²-Cl)(OSiMe₃)] (5) and Ti(iv) complexes with the pinacol condensation product [^MeNacNacTi(OSiMe₃)(η²-pinacolate)] (3), and phosphanylphosphaalkenes Ph₂C[double bond, length as m-dash]P-PtBu₂ (2) and (fluorenyl)C[double bond, length as m-dash]P-PtBu₂ (6), respectively. The reaction with acetophenone leads to the titanium(iii) complex with the aldol condensation product as ligand [^MeNacNacTi(Cl){OC{Me(Ph)}CH₂(C[double bond, length as m-dash]O)Ph}] (8) and in parallel to phosphanylphosphaalkene (Ph)MeC[double bond, length as m-dash]P-PtBu₂ (9) and 5. The reactions of 1 with cyclic ketones (cyclopentanone and cyclohexanone) lead to Ti(iii) complexes [{(ArN[double bond, length as m-dash]C(Me)CHC(Me)[double bond, length as m-dash]NAr)((CH₂)₄CO)}Ti(Cl){PtBu₂-P(SiMe₃)((CH₂)₄CO)}] (10) and [{(ArN[double bond, length as m-dash]C(Me)CHC(Me)[double bond, length as m-dash]NAr)((CH₂)₅CO)}Ti(Cl){PtBu₂-P(SiMe₃)((CH₂)₅CO)}] (11), which are formed via the successive insertion of two molecules of ketone to one molecule of 1. The stability investigation of complexes 10 and 11 in a polar solvent (THF) revealed that under these conditions, the complexes decompose, resulting in titanium(iii) complexes with aldol condensation products and the expected phosphanylphosphaalkenes (CH₂)₄C[double bond, length as m-dash]P-PtBu₂ (10a) and (CH₂)₅C[double bond, length as m-dash]P-PtBu₂ (11a). In the reaction of 1 with cycloheptanone, only the Ti(iii) complex with the aldol condensation product [^MeNacNacTi(Cl){OC(CH₂)₆}CH(C[double bond, length as m-dash]O)(CH₂)₅] (12) was isolated. The structures 3, 5, 8, 10, 11, 11b and 12 were characterized by X-ray spectroscopy, while all the phosphanylphosphaalkenes were characterized by NMR spectroscopy.