Cs2CO3-Promoted One-Pot Synthesis of Alkynylphosphonates, -phosphinates, and -phosphine Oxides

Recent Advances in the Application of P(III)-Nucleophiles to Create New P-C Bonds through Michaelis-Arbuzov-Type Rearrangement

Organophosphorus compounds have long been considered valuable in both organic synthesis and life science. P(III)-nucleophiles, such as phosphites, phosphonites, and diaryl/alkyl phosphines, are particularly noteworthy as phosphorylation reagents for their ability to form new P-C bonds, producing more stable, ecofriendly, and cost-effective organophosphorus compounds. These nucleophiles follow similar phosphorylation routes as in the functionalization of P-H bonds and P-OH bonds. Activation can occur through photocatalytic, electrocatalytic, or thermo-driven reactions, often in coordination with a Michaelis-Arbuzov-trpe rearrangement process, to produce the desired products. As such, this review offers a thorough overview of the phosphorylated transformation and potential mechanisms of P(III)-nucleophiles, specifically focusing on developments since 2010. Notably, this review may provide researchers with valuable insights into designing and synthesizing functionalized organophosphorus compounds from P(III)-nucleophiles, guiding future advancements in both research and practical applications.

Non-Noble-Metal Mono and Bimetallic Composites for Efficient Electrocatalysis of Phosphine Oxide and Acetylene C-H/P-H Coupling under Mild Conditions

The present work describes an efficient reaction of electrochemical phosphorylation of phenylacetylene controlled by the composition of catalytic nanoparticles based on non-noble-metals. The sought-after products are produced via the simple synthetic protocol based on room temperature, atom-economical reactions, and silica nanoparticles (SNs) loaded by one or two d-metal ions as nanocatalysts. The redox and catalytic properties of SNs can be tuned with a range of parameters, such as compositions of the bimetallic systems, their preparation method, and morphology. Monometallic SNs give phosphorylated acetylene with retention of the triple bond, and bimetallic SNs give a bis-phosphorylation product. This is the first example of acetylene and phosphine oxide C-H/P-H coupling with a regenerable and recyclable catalyst.

Pd-catalyzed synthesis of C-C (Sonogashira, Suzuki, Heck, Stille), C-P and C-S linked products using gem -dibromovinyl BODIPY

The chemistry of gem-dibromovinyl derivatives has undergone a renaissance through the application of palladium catalysis and has been applied to pyrrole substituted gem-dibromovinyl BODIPY. gem-Dibromovinyl BODIPYs (substituted at either the [Formula: see text]-position of 8-phenyl or the [Formula: see text]-position of the pyrrole rings) were studied for cross-coupling reactions using Sonogashira, Suzuki, Heck and Stille conditions, and with phosphonates and thiols. The assigned structures were supported by MS and 1H NMR, [Formula: see text]C NMR, X-ray diffraction analysis as well as optical spectroscopy. The conjugates were investigated for their absorption, fluorescence and solvatochromic properties in different solvents. Substitution at the [Formula: see text]-position of 8-phenyl derivatives of gem-diethynyl BODIPYs did not induce any shift in the absorption maximum, while the [Formula: see text]-position pyrrole substituted derivatives showed a red shift. Aromatic compounds gave larger red shifts as compared to the aliphatic substituted analogs.

Visible-Light-Induced Oxidative C-H Functionalization of Unreactive Cycloalkanes, Alcohols, and Ethers with Alkynylphosphine Oxides into Benzo[b]phosphole Oxides under Photocatalyst-, Metal-, and Base-Free Conditions

We developed the radical cyclization/addition of alkynylphosphine oxides with easily available cycloalkanes, alcohols, and ethers using a visible-light and environmentally friendly synthetic strategy in the absence of photocatalyst at room temperature. This mild and metal- and base-free reaction provided a structurally varied set of significant benzo[b]phosphole oxides through sequential C-H functionalization in an atom-economical manner.

Phosphorylation of Carboxylic Acids and Their Derivatives with P(O)–H Compounds Forming P(O)–C Bonds

Herein, we highlight advances in the phosphorylation of readily available carboxylic acids and their derivatives forming synthetically important P(O)–sp3C, P(O)–sp2C, and P(O)–spC bonds, with an emphasis on the results demonstrated since 2010. This review examines the challenges associated with the use of this strategy for the synthesis of organophosphorus compounds and details advances in the design of catalytic systems that suppress these problems thus resulting in notable progress. Mechanistic details are discussed where available.

1 Introduction

2 Formation of P(O)–sp3C Bonds

3 Formation of P(O)–sp2C Bonds

4 Formation of P(O)–spC Bonds

5 Outlook and Conclusion

TiO2/Cu2O nanoparticle-catalyzed direct C(sp)-P bond formation via aerobic oxidative coupling in air and visible light

The synthesis of organophosphorus compounds is one of the important goals in organic chemistry. Among these compounds, alkynylphosphonates are significantly utilized as the main precursors for the synthesis of biologically active molecules in medicinal chemistry and have attracted extensive interest in the past few decades. Although few efforts have been made towards the direct and atom-economical synthesis of alkynylphosphonates, efforts towards the utilization of visible light as a green and renewable energy source have not been made to date. Here, we have promoted a strategy to construct a type of nano metal oxide composite photocatalyst (Cu2O decorated on TiO2) for the synthesis of alkynylphosphonates via direct C-P bond formation between terminal alkyne and H-phosphonate under visible light irradiation. In this p-n heterojunction photocatalyst, Cu2O acted as a visible-light absorber; moreover, the CB (conduction band) of TiO2 was favorable for accepting a photogenerated electron, and the generated electron hole (e-/h+) pair could initiate the reaction. The present study can provide a new way for the synthesis of this important class of phosphorus organic compounds.

Cs2CO3-Mediated Rapid Room-Temperature Synthesis of 3-Amino-2-aroyl Benzofurans and Their Copper-Catalyzed N-Arylation Reactions

Cs₂CO₃ in dimethylformamide (DMF) is a perfect combination for the rapid room-temperature synthesis of 3-amino-2-aroyl benzofuran derivatives from the reaction of 2-hydroxybenzonitriles and 2-bromoacetophenones in good to excellent yields. Using this one-pot C-C and C-O bond-forming strategy, we prepared a series of 3-amino-2-aroyl benzofuran derivatives within a very short time (10-20 min). This method was also found suitable for gram-scale synthesis. Benzofurans (3) obtained by this Cs₂CO₃-mediated methodology were then further explored for the development of a tunable base- and ligand-free copper-catalyzed N-arylation methodology using arylboronic acids for the easy access of either mono- or bi-N-aryl derivatives of aminobenzofurans at ambient temperature. The reaction of 3 with malononitrile in DMF medium under microwave heating conditions provided highly fluorescent conjugated alkenes and novel pyridine-fused benzofurans.

Additive-free coupling of bromoalkynes with secondary phosphine oxides to generate alkynylphosphine oxides in acetic anhydride

A coupling of bromoalkynes with secondary phosphine oxides was developed to generate alkynylphosphine oxides under additive-free conditions in acetic anhydride.

An efficient preparation of β-ketophosphine oxides from alkynylphosphine oxides with benzaldehyde oxime as a hydroxide source

An effective transition-metal-free method has been developed for the preparation of β-ketophosphine oxides from alkynylphosphine oxides with benzaldehyde oxime.

Aerobic oxidative alkynylation of H-phosphonates and amides: an efficient route for the synthesis of alkynylphosphonates and ynamides using a recyclable Cu–MnO catalyst

We developed a straightforward, atom-economical and scalable route for the synthesis of alkynylphosphonates and ynamides using a reusable Cu–MnO catalyst.

Direct synthesis of alkynylphosphonates from alkynes and phosphite esters catalyzed by Cu/Cu2O nanoparticles supported on Nb2O5

A new, recyclable and efficient copper catalyst for cross-couplings of alkynes and phosphite esters has been disclosed, in which the synergistic effects of Nb₂O₅ on the catalyst are found owing to its strong Lewis acid sites.

Variable mechanism of nucleophilic substitution of P-stereogenic phosphoryl chloride with alkynyl metallic reagents

The variable mechanism for substitution of P-stereogenic phosphoryl chloride with alkynyl metallic reagents, which depends on temperature, stoichiometry of starting materials, and the structure of the nucleophilic reagent, is assumed as either SN2-like or Berry pseudorotation of pentacoordinated phosphorus intermediates, affording inversion and retention products, respectively. The formation of the inversion product can be controlled to occur predominantly to afford (RP)-alkynylphosphinates.

TBAI-catalyzed oxidative C–H functionalization: a new route to benzo[b]phosphole oxides

The first metal-free, efficient TBAI-catalyzed radical addition/cyclization of diaryl(arylethynyl)phosphine oxides with toluene derivatives has been developed, affording a general, one-step approach to structurally sophisticated benzo[b]phosphole oxides via sequential C–H functionalization along with the formation of two new C–C bonds.

Palladium-catalyzed dehydrogenative coupling of terminal alkynes with secondary phosphine oxides

The palladium-catalyzed dehydrogenative coupling of alkynes with secondary phosphine oxides is developed. Thus, in the presence of a silver additive, palladium acetate could efficiently catalyze the dehydrocoupling of secondary phosphine oxides with a variety of alkynes to produce the corresponding alkynylphosphine oxides in high yields. A reaction mechanism is proposed.

Palladium-catalyzed oxidative deacetonative coupling of 4-aryl-2-methyl-3-butyn-2-ols with H-phosphonates

A new and generally practical synthesis of alkynylphosphonates through a palladium-catalyzed consecutive Sonogashira/deacetonative process using aryl bromides, 2-methyl-3-butyn-2-ol and H-phosphonates is developed.

Room temperature alkynylation of H-phosphi(na)tes and secondary phosphine oxides with ethynylbenziodoxolone (EBX) reagents

We report the alkynylation of H-phosphi(na)tes and secondary phosphine oxides at room temperature using ethynylbenziodoxolone (EBX) reagents.