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Open AccessCCS ChemistryCOMMUNICATIONS1 Jan 2024

Direct Synthesis of α-Aminophosphonates from Amines, Alcohols, and White Phosphorus

    CCS Chem. 2024, 6, 91–99
    https://doi.org/10.31635/ccschem.023.202303143

    Developing practical strategies for the synthesis of organophosphorus compounds (OPCs) from white phosphorus (P4) without the use of Cl2 and PCl3 remains a significant challenge. The first multicomponent oxidative α-phosphonylation of amines with P4 and alcohols has been developed. With the use of copper(II) as the catalyst and air as the safe oxidant, structurally sophisticated α-aminophosphonates have been prepared in high yields. Furthermore, this method is also suitable for selective construction of P–O–P compounds. The reaction is characterized by a complete conversion of P4. The activation of P4 with transition metals often leads to formation of complexes [MxPy]n associated with the deactivation of transition metals. This breakthrough showcases the potential of transition-metal-catalyzed reactions in elemental phosphorus chemistry.

    Introduction

    Demands for efficient construction of valuable organophosphorus compounds (OPCs) from industrial inorganic phosphorus compounds have received widespread attention.1–4 However, there are few reports on the preparation of structurally sophisticated phosphorus compounds containing both P–C and P–X (X = N, O, S, etc.) bonds in one step from white phosphorus (P4).5–7 In the past decade, catalytic phosphonylation reactions using dialkyl phosphites [DAPIs, (RO)2P(O)H] as building blocks for constructing P–C bonds have been well known (Figure 1).8–10 The industrial process for the preparation of P–X bonds is first chlorination of P4 to generate PCl3, followed by the phosphorylation of organic reagents, along with the release of amounts of HCl.11–15 In contrast, direct synthesis of OPCs from P4 are a highly attractive idea because it avoids numerous issues, including environmental pollution, safety concerns, high recycling costs, and low efficiency.16–18 However, this approach is still limited due to challenges faced by transition-metal-catalyzed functionalization of P4.19–21 These challenges include the activation of P4 with transition metals, which often leads to the formation of [MxPy]n complexes associated with the deactivation of transition metals,22–25 and the difficulty in selective cleavage of the same six P–P bonds in P4.26–28

    Figure 1

    Figure 1 | Synthesis of α-aminophosphonates and pyrophosphates from P4.

    α-Aminophosphonates are natural α-amino acid structural analogs with widespread applications, ranging from fungicides to enzyme inhibitors.29 Traditional methods for synthesizing α-aminophosphonates involve the condensation between DAPIs and imines (Figure 1). In recent years, several alternative strategies for synthesizing these compounds using DAPIs and amines have been explored, such as transition-metal-catalyzed cross-dehydrogenative coupling reactions30–33 and photocatalytic reactions.34 Based on these studies, we became interested in the development of oxidative phosphonylation of amines with P4 via a domino multicomponent reaction. This method not only provides the first example of phosphonylation of sp3-carbon atoms with P4 but also showcases the potential of transition-metal-catalyzed multicomponent reactions in elemental phosphorus chemistry.

    We report here the merger of copper(II) catalysis and air oxidation for P–C and P–O bond formation using tetrahydroisoquinolines, alcohols, and P4 as starting materials. Owing to the reactive DAPIs as the key intermediates,35,36 we also disclose the first copper-catalyzed synthesis of pyrophosphates [P(O)–O–P(O) bonds] from P4 by slightly changing the reaction conditions (Figure 1). This approach not only simplifies the synthetic process but also offers a more environmentally friendly alternative compared to traditional methods.

    Results and Discussion

    Reaction development

    We focused our initial studies on optimizing the reaction conditions using P4, N-phenyl tetrahydroisoquinoline (N-phenyl THIQ, 2a), and ethanol ( 3a) as model substrates (Table 1, see Supporting Information Scheme S1 and Tables S1–S5 for details). After extensive screening of solvents, catalysts, concentrations, and temperatures, the desired product 4a was obtained in almost quantitative yield when the oxidative phosphonylation of 2a was conducted under dry air, using Cu(OAc)2 as the catalyst and 1,2-dichloroethane (DCE) as the solvent at 70 °C for 24 h (entry 1 in Table 1). Other copper salts, such as CuCl2, CuBr2, CuI, CuCl, and CuBr, gave 4a in lower yields (25–85%, entry 2). When cobalt, nickel, and iron salts were tested, most performed poorly (entry 3). DCE was found to be the optimal solvent for this reaction (entry 4). Decreasing the amount of ethanol to 5 equiv resulted in an 81% yield of 4a (entries 1 and 5) while decreasing the amount of 2a led to much lower yields (entry 6). Furthermore, temperature screening indicated that temperature control was also very crucial for the reaction. The yield of product 4a decreased drastically when the temperature was decreased from 70 to 50 °C (entries 1 and 7). The reaction was inhibited in the absence of either copper salt or dry air conditions (entries 8 and 9).

    Table 1 | Optimization of Reaction Conditionsa
    if1.eps
    Entry Deviation from Standard Conditions Yieldb (%)
    1 None Quant. (95)c
    2 Other copper salts instead of Cu(OAc)2 25–85
    3 Co(OAc)2, Ni(OAc)2, FeCl3 instead of Cu(OAc)2 n.d.d
    4 Other solvents instead of DCE <32
    5 EtOH (5 equiv) 81
    6 2a (1 equiv) <40
    7 50 °C instead of 70 °C Trace
    8 Ar instead of dry air n.d.
    9 No copper salt <10

    aStandard conditions: P4 (6.20 mg, a 0.5 M solution of P4 in toluene, 0.4 mL), 2a (83.6 mg, 0.4 mmol, 2 equiv), 3a (93 μL, 1.6 mmol, 8 equiv), Cu(OAc)2 (5.46 mg, 0.03 mmol, 15 mol %), in DCE (4 mL), stirring at 70 °C for 24 h under dry air conditions (with a CaCl2 drying tube).

    bYield of product determined by 31P{1H} NMR analysis of the crude reaction mixture using (C6H5)3P(O) as an internal standard. The data were not corrected for the influence of molecular relaxation time and nuclear overhauser effect.

    cIsolated yield is shown in parentheses.

    dn.d., not detected.

    Synthesis of α-aminophosphonates

    We next explored the substrate scope of the C–H phosphonylation reaction using a wide range of N-aryl tetrahydroisoquinolines (N-aryl THIQs) (Figure 2, Supporting Information Schemes S2–S5 and S10). The N-tethered phenyl ring tolerated substitution at the para position with F ( 4b), Cl ( 4c), Br ( 4d), OMe ( 4e), Me ( 4f), and NHBoc ( 4n), at the meta position with Me ( 4g) and at the ortho position with Me ( 4h). The N-tethered phenyl ring was also replaced with a biphenyl( 4i), 2-napthalenyl ( 4j), and 1-natphalenyl ( 4k) group. However, when the benzene ring contained a strong electron-withdrawing group, such as –CF3, –NO2 ( 4l and 4m), no desired product was obtained. N-benzyl THIQ could not provide the desired product 4o under standard conditions, but the addition of 0.5 equiv of N-hydroxyphthalimide (NHPI) promoted the reaction, resulting in a moderate yield of 4o ( Supporting Information Scheme S6). Other tertiary amines, such as 1-phenyl piperidine, N,N-dimethylaniline, and tributylamine were also tried. Unfortunately, no P–C bond-forming products were detected by 31P {1H} NMR. Only some complicated signals at δ 7 to −2 ppm appeared.

    Figure 2

    Figure 2 | Scope of amine. Reaction conditions from Table 1, entry 1. Isolated yields were reported based on P atom (12.4 mg, 0.4 mmol). aReaction time: 67 h. bNHPI (0.5 equiv) was added.

    The reaction compatibility with different alcohols was next explored by using N-phenyl THIQ ( 2a) as the coupling partner (Figure 3). To our gratification, our method was found to be broadly compatible with alcohols. Methanol ( 4ab), isopropyl alcohol ( 4ac), n-butanol ( 4ad), and bulkier n-nonanol ( 4ae) were well tolerated. Alcohol carrying a Cl atom, such as 4af, successfully ,participated in this procedure of oxidative phosphonylation. Furthermore, the standard conditions tolerated an aliphatic amide ( 4ag) and a furan amide ( 4ah) ( Supporting Information Schemes S7 and S8). When the aryl-substituted alcohols were employed as the substrates, products 4ai– 4an were obtained in the range of 56–95%. Benzyl alcohol ( 4aj), 2-(4-chlorophenyl)ethanol ( 4ai), 2-(thiophen-2-yl)ethanol ( 4ak), and 2-phenoxyethan-1-ol ( 4al) all produced the desired products in good yields. β-Substituted aliphatic primary alcohol with bulkier groups afforded the product 4am in 77% yield, and the spatially hindered 9-fluorenylmethanol was also tolerated, providing the target product 4an in moderate yield. The mild conditions ensured substrate compatibility with both alkenes ( 4ao, 4ap, and 4at) and internal alkynes ( 4aq).

    Figure 3

    Figure 3 | Scope of alcohol. Reaction conditions from Table 1, entry 1. Isolated yields were reported based on P atom (12.4 mg, 0.4 mmol).

    Disappointingly, terminal and trimethylsilyl (TMS)-protected alkynes were very sensitive to this reaction system, and no desired products ( 4au and 4av) were obtained. Cyclic secondary alcohols produced the corresponding products 4ar–4at in good yields. No 4aw was detected, and a large amount of P4 remained when tert-butanol was applied. In all the transformations mentioned above, no other P-containing compounds were detected, even with low yields. To demonstrate the method’s application potential, a gram-scale reaction of P4 (124 mg) with N-phenyl THIQ ( 2a) and n-nonanol ( 3f) was employed, delivering 4af in 72% yield.

    Subsequently, some different diols were examined, and we discovered that the corresponding phosphorus-containing pentacyclic products could be generated when ethylene glycol ( 4aa′), butane-2,3-diol ( 4ab′), and cyclohexane-1,2-diol ( 4ac′) were used (Figure 4). Among them, cis diols gave more stable and higher yields compared to cis-trans-mixed diols in the reaction. However, when propane-1,3-diol ( 4ad′) was used as the substrate, the desired phosphorus-containing hexacyclic product was not detected.

    Figure 4

    Figure 4 | Scope of diol. Reaction conditions from Table 1, entry 1. Isolated yields were reported based on P atom (12.4 mg, 0.4 mmol).

    Synthesis of pyrophosphates

    Pyrophosphates play an important role in various biological processes and have numerous applications, including as enzyme inhibitors, flame retardants, and anticancer drugs.37 We then speculated about whether this copper catalytic strategy could be used to produce valuable pyrophosphate esters (Figure 5 and Supporting Information Scheme S11).38 The model reaction of P4 with isopropanol 3b was optimized ( Supporting Information Tables S6–S8). With CuCl2 as the best catalyst and 1,4-dioxane as the best solvent, the reaction was performed at 70 °C for 36 h to afford the desired product 5b in 55% yield. A series of chain primary alcohols selected as substrates provided the corresponding pyrophosphate esters 5a–5c in satisfactory yields. No other P-containing products were detected by 31P NMR. Using 2-cyclohexyl ethanol and 2-phenylethanol as substrates, the corresponding pyrophosphates 5d and 5e were formed in 67% and 72% 31P{1H} NMR yields, respectively, along with a portion of trialkyl phosphate esters (20%–30%). It is important to note that anhydrous conditions are required to avoid the generation of H3PO4 and (RO)PO3H2 byproducts.

    Figure 5

    Figure 5 | Synthesis of pyrophosphates from P4. aIsolated yields of 5a, 5b and 5c were reported based on P atom (24.8 mg, 0.8 mmol). TMEDA, N,N,N′,N′-tetramethylethylenediamine. b31P{1H} NMR yield.

    Mechanistic studies

    In situ NMR studies of the reaction were conducted, and the corresponding 31P{1H} NMR spectra are shown in Figure 6 and Supporting Information Figure S1. After stirring the reaction mixture at 70 °C for 30 min, the signal peak (δ 522.75 ppm) of P4 was largely retained, and no new peak was detected. When the reaction proceeded for 4 h, a signal appeared at 22.0 ppm (Figure 6a), indicating the formation of 4ae. After 12 h, P4 was further consumed, and the product peak 4ae gradually increased. Meanwhile, a new peak was detected at 7.4 ppm, indicating the existence of the intermediate of (RO)2P(O)H (R: 4-chloro-1-butanol, Figure 6b).

    Figure 6

    Figure 6 | In situ 31P{1H} NMR spectra for the synthesis of 4ae. 4-chloro-1-butanol and THIQ 2a were used in these reactions.

    After 24 h, full consumption of P4 was observed, with 4ae being the only phosphorus-containing compound (Figure 6c). To further identify the key intermediate (RO)2P(O)H (Figure 7, see Supporting Information Schemes S12–S17 and Figure S2–S13), a reaction of 4-chloro-1-butanol ( 3e) and P4 was carried out under the standard condition, yielding 6e in 35% yield (Figure 7a). This intermediate 6e reacted directly with THIQ 2a to afford 4ae in 75% yield (Figure 7b). When the reaction between 3e and P4 was performed under argon for 24 h, 6e and a small amount of 7 were generated (Figure 7c). To determine whether (RO)(HO)P(O)H was another intermediate in this reaction, we used (PhCH2CH2O)(HO)P(O)H ( 7y) as the P atom source to react with phenylethanol ( 3y) under the standard condition, and the generation of (PhCH2CH2O)2P(O)H ( 6y) was not detected. However, when 2a was added to the reaction, the desired product ( 4ay) was obtained in 54% yield (Figure 7e). N-aryl-THIQ may promote the conversion of (PhCH2CH2O)(HO)P(O)H to (PhCH2CH2O)2P(O)H. On the contrary, the presence of N-aryl-THIQ may inhibit the conversion of (C4H9O)3P to (C4H9O)2P(O)H. When (C4H9O)3P was used as the P atom source under the standard condition, the formation of (C4H9O)2P(O)H ( 6d) was detected in 44% yield. However, the yield of the desired product ( 4ad) was low when 2a was added to the reaction, and most of (C4H9O)3P was converted to (C4H9O)3P(O) ( 9) (Figure 7d). Subsequently, we used n-decanol labeled with 18O ( 3x) as the substrate to react with P4 and amine under the standard condition and determined the source of oxygen atoms in P=O by detecting the content of 18O in the product ( 4ax) using HRMS (Figure 7f, Supporting Information Figure S14 and Schemes S18 and S19). The highest peak in the mass spectrum was 4ax with two 18O labels, followed by 4ax with a single 18O label. Only a small amount of 4ax with three 18O labels was observed. The approximate ratio of the above compounds was 9:5:2. According to the above control experiments and the 18O labeling experiment, (RO)3P may only be a less important intermediate. Furthermore, it was found that 4a was obtained in high yield when 6 equiv of butylated hydroxytoluene (BHT) or 1,1-diphenylethylene were added, suggesting that a radical reaction may not be involved (Figure 7g). We also conducted a control experiment on the order of reactant addition. When P4 was reacted with copper salt at 70 °C for 10 min before adding alcohol and amine, the reaction yield decreased sharply, and most of the P4 remained (Figure 7h, Supporting Information Figure S15 and Scheme S20). P4 and copper are prone to forming complex metal-phosphorus complexes [CuxPy]n, which are brown-black insoluble solids. Currently, we are unable to separate and characterize the intermediates. Therefore, the working mechanism between copper and P4 is still unknown.

    Figure 7

    Figure 7 | Control experiments.

    Although the detailed mechanism of the Cu(II)-catalyzed oxidative α-phosphonylation of amines with P4 remains ambiguous at present, a possible pathway is suggested and described in Figure 8. Cu(II)-catalyzes the ring opening of P4 by ROH, forming intermediate A. The intermediate A undergoes repeated cleavage of the P–P bond of P4 in a similar manner to form the intermediates (RO)PH2 ( B) and (RO)2PH ( C). Both intermediates are then oxidized by air to afford the intermediates (RO)(HO)P(O)H ( D) and (RO)2P(O)H ( E). Lewis acid Cu(II) catalyzes the esterification between D and ROH, producing (RO)2P(O)H ( E).4 Preliminary 31P NMR studies (Figure 6) and control experiments (Figure 7a,b) showed that (RO)2P(O)H ( E) was involved as a key intermediate in the reaction. On the other hand, iminium cation intermediate F is formed through Cu(II)-catalyzed air oxidation of THIQ. Further addition of E to the iminium cation F yields the desired α-phosphonylation product.32,33

    Figure 8

    Figure 8 | Tentative mechanistic pathway.

    Conclusion

    In summary, the first example of direct construction of α-aminophosphonates using P4, tetrahydroisoquinolines and alcohols has been successfully developed. This domino multicomponent reaction involves (1) copper-catalyzed selective synthesis of (RO)2P(O)H from P4, (2) copper-catalyzed air oxidation of tetrahydroisoquinolines, and (3) nucleophilic addition of (RO)2P(O)H to iminium cations. This economic and green approach enables the direct use of P4 as the P-atom source and offers substrate compatibility with various functional groups. Advantageously, the catalytic system can also synthesize pyrophosphate esters from P4. By establishing this novel approach to synthesizing α-aminophosphonates, we can continue to push the boundaries of P4 chemistry, ultimately leading to the development of greener and more efficient synthetic methods for a wide range of applications.

    Supporting Information

    Supporting Information is available and includes general information, experimental procedures, product characterization data, and copies of 1H, 13C, and 31P NMR spectra of all the products.

    Conflict of Interest

    There is no conflict of interest to report.

    Funding Information

    We gratefully acknowledge financial support from the National Key Research and Development Program of China (grant no. 2020YFA0608300), the Space Application System of China Manned Space Program (grant no. KJZ-YY-WSM01), and National Natural Science Foundation of China (grant nos. 21772163, 21778042, and 41876072).

    References

    • 1. Geeson M. B.; Cummins C. C.Let’s Make White Phosphorus Obsolete.ACS Cent. Sci.2020, 6, 848–860. Google Scholar
    • 2. Mei Y.; Yan Z.; Liu L. L.Facile Synthesis of the Dicyanophosphide Anion via Electrochemical Activation of White Phosphorus: An Avenue to Organophosphorus Compounds.J. Am. Chem. Soc.2022, 144, 1517–1522. Google Scholar
    • 3. Qian D-W.; Yang J.; Wang G-W.; Yang S-D.Nickel-Catalyzed Sodium Hypophosphite-Participated Direct Hydrophosphonylation of Alkyne toward H-Phosphinates.J. Org. Chem.2023, 88, 3539–355. Google Scholar
    • 4. Fisher H. C.; Prost L.; Montchamp J.-L.Organophosphorus Chemistry without PCl3: A Bridge from Hypophosphorous Acid to H-Phosphonate Diesters.Eur. J. Org. Chem.2013, 2013, 7973–7978. Google Scholar
    • 5. Scott D. J.Recent Breakthroughs in P4 Chemistry: Towards Practical, Direct Transformations into P1 Compounds.Angew. Chem. Int. Ed.2022, 61, e202205019. Google Scholar
    • 6. Fang W.; Douair I.; Hauser A.; Li K.; Zhao Y.; Roesky P. W.; Wang S.; Maron L.; Zhu C.Uranium(III)-Phosphorus(III) Synergistic Activation of White Phosphorus and Arsenic.CCS Chem.2021, 3, 3268–3276. Google Scholar
    • 7. Hu J.; Chai Z.; Liu W.; Huang Z.; Wei J.; Zhang W.-X., Phosphafluorenyl Lithiums: Direct Synthesis from White Phosphorus, Structure and Diversified Synthons.Sci. China Chem.2021, 65, 322–327. Google Scholar
    • 8. Zheng Z.; He J.; Ma Q.; Zhang Y.; Liu Y.; Tang G.; Zhao Y.Photoredox/Copper-Catalyzed Coupling of Terminal Alkynes with P(O)SH Compounds Leading to Alkynyl Phosphorothioates.Green Chem.2022, 24, 4484–4489. Google Scholar
    • 9. Gan L.; Xu T.; Tan Q.; Cen M.; Wang L.; Zhao J.; Liu K.; Liu L.; Chen W-H.; Han L-B.; Nycz J. E.; Chen T.Metal-Free Highly Chemo-Selective Bisphosphorylation and Deoxyphosphorylation of Carboxylic Acids.Chem. Sci.2023, 14, 5519–5526. Google Scholar
    • 10. Guo Y.; Luo Y.; Mu S.; Su J.; Xu J.; Song Q.Design, Synthesis, and Applications of ortho-Sulfur Substituted Arylphosphanes.CCS Chem.2023, 5, 1353–1364. Link, Google Scholar
    • 11. Chen F.; Bai M.; Zhang Y.; Liu W.; Huangfu X.; Liu Y.; Tang G.; Zhao Y.Decarboxylative Selective Phosphorylation of Aliphatic Acids: A Transition-Metal- and Photocatalyst-Free Avenue to Dialkyl and Trialkyl Phosphine Oxides from White Phosphorus.Angew. Chem. Int. Ed.2022, 61, e202210334. Google Scholar
    • 12. Till M.; Streitferdt V.; Scott D. J.; Mende M.; Gschwind R. M.; Wolf R.Photochemical Transformation of Chlorobenzenes and White Phosphorus into Arylphosphines and Phosphonium Salts.Chem. Commun.2022, 58, 1100–1103. Google Scholar
    • 13. Lennert U.; Arockiam P. B.; Streitferdt V.; Scott D. J.; Rodl C.; Gschwind R. M.; Wolf R.Direct Catalytic Transformation of White Phosphorus into Arylphosphines and Phosphonium Salts.Nat. Catal.2019, 2, 1101–1106. Google Scholar
    • 14. Donath M.; Schwedtmann K.; Schneider T.; Hennersdorf F.; Bauza A.; Frontera A.; Weigand J. J.Direct Conversion of White Phosphorus to Versatile Phosphorus Transfer Reagents via Oxidative Onioation.Nat. Chem.2022, 14, 384–391. Google Scholar
    • 15. Scott D. J.; Cammarata J.; Schimpf M.; Wolf R.Synthesis of Monophosphines Directly from White Phosphorus.Nat. Chem.2021, 13, 458–464. Google Scholar
    • 16. Huangfu X.; Wang Y.; Lu G.; Cao Y.; Tang G.; Zhao Y.Direct Synthesis of Phosphorotrithioites and Phosphorotrithioates from White Phosphorus and Thiols.Green Chem.2020, 22, 5303–5309. Google Scholar
    • 17. Lu G.; Chen J.; Huangfu X.; Li X.; Fang M.; Tang G.; Zhao Y.Visible-Light-Mediated Direct Synthesis of Phosphorotrithioates as Potent Anti-Inflammatory Agents from White Phosphorus.Org. Chem. Front.2019, 6, 190–194. Google Scholar
    • 18. Zhang Y.; Cai Z.; Chi Y.; Zeng X.; Chen S.; Liu Y.; Tang G.; Zhao Y.Diphenyl Diselenide-Catalyzed Synthesis of Triaryl Phosphites and Triaryl Phosphates from White Phosphorus.Org. Lett.2021, 23, 5158–5163. Google Scholar
    • 19. Zhang Y.; Cao Y.; Chi Y.; Chen S.; Zeng X.; Liu Y.; Tang G.; Zhao Y.Formation of N−P(O)−S Bonds from White Phosphorus via a Four-Component Reaction.Adv. Synth. Catal.2022, 364, 2221–2226. Google Scholar
    • 20. Huangfu X.; Zhang Y.; Chen P.; Lu G.; Cao Y.; Tang G.; Zhao Y.Synthesis of Mixed Phosphorotrithioates from White Phosphorus.Green Chem.2020, 22, 8353–8359. Google Scholar
    • 21. He J.; Shi S.; Zhang Y.; Zhang Y.; Xu P.; Tang G.; Zhao Y.Synthesis of Tetrathiophosphates from White Phosphorus.Chin. J. Chem.2023, 41, 2311–2316. Google Scholar
    • 22. Du S.; Yin J.; Chi Y.; Xu L.; Zhang W. X.Dual Functionalization of White Phosphorus: Formation, Characterization, and Reactivity of Rare-Earth-Metal Cyclo-P3 Complexes.Angew. Chem. Int. Ed.2017, 56, 15886–15890. Google Scholar
    • 23. Bishimbaeva G. K.; Nalibaeva A. M.; Polimbetova G. S.; Borangazieva A. K.; Ibraimova Z. U.; Zhanabaeva A. K.Catalytic Synthesis of Phosphorus-Containing Extractant: Tributyl Phosphate.Russ. J. Appl. Chem.2019, 92, 543–548. Google Scholar
    • 24. Xu L.; Chi Y.; Du S.; Zhang W. X.; Xi Z.Direct Synthesis of Phospholyl Lithium from White Phosphorus.Angew. Chem. Int. Ed.2016, 55, 9187–9190. Google Scholar
    • 25. Frötschel-Rittmeyer J.; Holthausen M.; Friedmann C.; Röhner D.; Krossing I.; Weigand J. J.Homoatomic Cations: From [P5]+ to [P9]+.Sci. Adv.2022, 8, eabq8613. Google Scholar
    • 26. Barton D. H. R.; Zhu J. P.Elemental White Phosphorus as a Radical Trap: A New and General Route to Phosphonic Acids.J. Am. Chem. Soc.1993, 115, 2071–2072. Google Scholar
    • 27. Volkov P. A.; Khrapova K. O.; Telezhkin A. A.; Malysheva S. F.; Larina L. I.; Trofimov B. A.Synthesis of Alkyl-H-Phosphinic Acid Alkyl Esters from Red Phosphorus and Alkyl Bromides.Mendeleev Commun.2022, 32, 792–794. Google Scholar
    • 28. Cossairt B. M.; Cummins C. C.Radical Synthesis of Trialkyl, Triaryl, Trisilyl and Tristannyl Phosphines from P4.New J. Chem.2010, 34, 1533–1536. Google Scholar
    • 29. Yang Z.; Du Q.; Jiang Y.; Wang J.Asymmetric Access of γ-Amino Acidsand γ-Amino Phosphonic Acid Derivatives via Copper-Catalyzed Enantioselective and Regioselective Hydroamination.CCS Chem.2022, 4, 1901–1911. Link, Google Scholar
    • 30. Basle O.; Li C. J.Copper-Catalyzed Aerobic Phosphonation of sp3 C-H Bonds.Chem. Commun.2009, 4124–4126. Google Scholar
    • 31. Han W.; Ofial A. R.Iron-Catalyzed Dehydrogenative Phosphonation of N,N-Dimethylanilines.Chem. Commun.2009, 6023–6025. Google Scholar
    • 32. Lin B.; Shi S.; Lin R.; Cui Y.; Fang M.; Tang G.; Zhao Y.Cobalt-Catalyzed Oxidative C(Sp3)-H Phosphonylation for α-Aminophosphonates via C(Sp3)-H/P(O)-H Coupling.J. Org. Chem.2018, 83, 6754–6761. Google Scholar
    • 33. Boess E.; Sureshkumar D.; Sud A.; Wirtz C.; Fares C.; Klussmann M.Mechanistic Studies on a Cu-Catalyzed Aerobic Oxidative Coupling Reaction with N-Phenyl Tetrahydroisoquinoline: Structure of Intermediates and the Role of Methanol as a Solvent.J. Am. Chem. Soc.2011, 133, 8106–8109. Google Scholar
    • 34. Yi M. J.; Xiao T. F.; Li W. H.; Zhang Y. F.; Yan P. J.; Zhang B.; Xu P. F.; Xu G. Q.Organic Photoredox Catalytic α-C(Sp3)-H Phosphorylation of Saturated Aza-Heterocycles.Chem. Commun.2021, 57, 13158–13161. Google Scholar
    • 35. Cai Z.; Zeng X.; Zhang Y.; Liu Y.; Tang G.; Zhao Y.Direct Synthesis of Dialkylphosphites from White Phosphorus.Adv. Synth. Catal.2022, 364, 2916–2921. Google Scholar
    • 36. Cai Z, Zhang Y, Cao Y; Liu Y, Tang G, Zhao Y.Ternary Photoredox/Nickel/Halide Catalysis for the Phosphorylation of Alcohols with White Phosphorus.ACS Catal.2023, 13, 8330–8335. Google Scholar
    • 37. Prasher P.; Sharma M.Medicinal Chemistry of Pyrophosphate Mimics: A Mini Review.Drug Dev. Res.2022, 83, 3–15. Google Scholar
    • 38. Zhou Y.; Yin S.; Gao Y.; Zhao Y.; Goto M.; Han L. B.Selective P–P and P–O–P Bond Formations Through Copper-Catalyzed Aerobic Oxidative Dehydrogenative Couplings of H-Phosphonates.Angew. Chem. Int. Ed.2010, 49, 6852–6855. Google Scholar
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