Diselenide-Mediated Catalytic Functionalization of Hydrophosphoryl Compounds

Facile Synthesis of H-Phosphinates from P(OR)3 or ClP(OR)2 via SiO2-Promoted Hydrolysis

H-Phosphinates represent a valuable class of organophosphorus building blocks and catalytic ligands. The existing synthetic approaches are generally associated with the use of strong acids, the need for meticulous treatment of intermediates, and the limitation of only P-aryl introductions. Following a comprehensive investigation into the unexpected SiO2-promoted hydrolysis observed during the chromatography workup of the crude R'P(OR)2 intermediates, we have developed an extremely simple and general synthetic route to H-phosphinates from commercially available Grignard reagents and P(OR)3. An alternative approach involved the use of ClP(OR)2 in place of P(OR)3, which proved to be a valuable strategy for the preparation of sterically hindered ArMgBr substrates bearing bulky ortho-substituted motifs. A library of 36 structurally diverse P-(cyclo)alkyl and P-(hetero)aryl H-phosphinates was thus obtained in moderate to high yields using this practical protocol. Furthermore, the CuCl2-mediated P(O)-H bond derivations were also examined, resulting in the formation of the corresponding EtOPhP(O)-X (X = O, N, S) compounds in nearly quantitative yields.

Tf2O-Mediated P(O)-N Bond Formation of Either P(O)-OH or P(O)-H Reagents with Multitype Amines

We have developed a Tf2O-mediated approach for the direct amination of either P(O)-OH or P(O)-H reagents with a variety of aliphatic or aromatic amines. Without the requirement of precious metals and toxic reagents, this protocol provides an alternative route to various phosphinamides and phosphoramides. The reaction proceeds under simple and mild conditions and can be effectively scaled up with similar efficiency.

Construction of C-P Bonds from Free Cyclobutanone Oximes and Chlorophosphines via Radical-Radical Coupling

Herein, we report a catalyst-free reaction of cyclobutanone oximes with chlorophosphines (R2PCl), which forms a fragile C═N-O-PR2 species that undergoes N-O homolysis, fragmentation, and radical-radical coupling, leading to the formation of cyano-containing phosphine oxides in good yields. The reaction features an in situ activation of cyclobutanone oximes for radical generation, in which R2PCl plays a dual role as both an activator and a reactant.

Recent Advances in the Use of Diorganyl Diselenides as Versatile Catalysts

The importance of organoselenium compounds has been increasing in synthetic chemistry. These reagents are well-known as electrophiles and nucleophiles in many organic transformations, and in recent years, their functionality as catalysts has also been largely explored. The interest in organoselenium-based catalysts is due to their high efficacy, mild reaction conditions, strong functional compatibility, and great selectivity. Allied to organoselenium catalysts, the use of inorganic and organic oxidants that act by regenerating the catalytic species for the reaction pathway is common. Here, we provide a comprehensive review of the last five years of organic transformations promoted by diorganyl diselenide as a selenium-based catalyst. This report is divided into four sections: (1) cyclisation reactions, (2) addition reactions and oxidative functionalisation, (3) oxidation and reduction reactions, and (4) reactions involving phosphorus-containing starting materials.

Copper-cobalt double metal cyanides as green catalysts for phosphoramidate synthesis

Phosphoramidates are common and widespread backbones of a great variety of fine chemicals, pharmaceuticals, additives and natural products. Conventional approaches to their synthesis make use of toxic chlorinated reagents and intermediates, which are sought to be avoided at an industrial scale. Here we report the coupling of phosphites and amines promoted by a Cu₃[Co(CN)₆]₂-based double metal cyanide heterogeneous catalyst using I₂ as additive for the synthesis of phosphoramidates. This strategy successfully provides an efficient, environmentally friendly alternative to the synthesis of these valuable compounds in high yields and it is, to the best of our knowledge, the first heterogeneous approach to this protocol. While the detailed study of the catalyst structure and of the metal centers by PXRD, FTIR, EXAFS and XANES revealed changes in their coordination environment, the catalyst maintained its high activity for at least 5 consecutive iterations of the reaction. Preliminary mechanism studies suggest that the reaction proceeds by a continuous change in the oxidation state of the Cu metal, induced by a O₂/I^- redox cycle.

Nickel-Catalyzed Sodium Hypophosphite-Participated Direct Hydrophosphonylation of Alkyne toward H-Phosphinates

The traditional methods for the synthesis of phosphinate esters use phosphorus trichloride (PCl₃) as the phosphorous source, resulting in procedures that are often highly polluting and energy intensive. The search for an alternative approach that is both mild and environmentally friendly is a challenging, yet highly rewarding task in modern chemistry. Herein, we use an inorganic phosphorous-containing species, NaH₂PO₂, to serve as the source of phosphorous that participates directly in the nickel-catalyzed selective alkyne hydrophosphonylation reaction. The transformation was achieved in a multicomponent fashion and at room temperature, and most importantly, the H-phosphinate product generated is an advanced intermediate which can be readily converted into diverse phosphinate derivatives, including those bearing new P-C, P-S, P-N, P-Se, and P-O bonds, thus providing a complimentary method to classic phosphinate ester synthesis techniques.

Copper-Catalyzed Phosphorylation of N,N-Disubstituted Hydrazines: Synthesis of Multisubstituted Phosphorylhydrazides as Potential Anticancer Agents

An efficient copper-catalyzed aerobic oxidative cross-dehydrogenative coupling reaction for the synthesis of multisubstituted phosphorylhydrazides from N,N-disubstituted hydrazines and hydrogen phosphoryl compounds is accomplished. The reaction proceeds under mild conditions without the addition of any external oxidants and bases. This work reported here represents a direct P(═O)-N-N bond formation with the advantages of being operationally simple, good functional group tolerance, and high atom and step economy. Furthermore, the selected compounds exhibit potential inhibitory activity against tumor cells, which can be used in the field of screening of anticancer agents as new chemical entities.

Recent advances in the synthesis and applications of phosphoramides

Phosphoramide, as an important framework of many biologically active molecules, has attracted widespread attention in recent decades. It is not only widely used in pharmaceuticals because of its excellent biological activities, but it also shows good performance in organic dyes, flame retardants and extractors. Thus, it is of great significance to develop effective and convenient methods for the synthesis of phosphoramides. In this review, the recent advancements made in the synthesis routes and applications of phosphoramides are discussed. The synthetic strategies of phosphoramides can be separated into five categories: phosphorus halides as the substrate, phosphates as the substrate, phosphorus hydrogen as the substrate, azides as the substrate and other methods. The latest examples of these methods are provided and some representative mechanisms are also described.

Electrochemical phosphorylation of arenols and anilines leading to organophosphates and phosphoramidates

A practical phosphorylation for generating organophosphates and phosphoramidates via electrochemical dehydrogenative cross-coupling of P(O)H compounds with arenols and anilines is disclosed. This method involves using inorganic iodide salts as both redox catalysts and electrolytes in an undivided cell without the addition of oxidants or bases. A preliminary mechanistic study suggests that radicals are not involved in this process. This method is green and eco-friendly and has good functional group tolerance, high yields and broad substrate scope, with the potential for practical synthesis.

Synthesis of Selenium-Containing Polystyrene Microspheres and Using as Catalyst for Oxidation of Acrolein

Selenium-containing polystyrene (DSe-PS) microspheres were synthesized by soap-free emulsion polymerization using 1,2-bis(2,3,5,6-tetrafluoro-4-vinylphenyl)diselane (FVPDSe) and divinylbenzene (DVB) as crosslinking agents. The particle size of the obtained DSe-PS was characterized by a scanning electron microscope and dynamic light scattering. The results showed that the diameter of the obtained DSe-PS microspheres could be adjusted by changing the ratio of the monomer and crosslinker/water. The diselenide moiety in the obtained DSe-PS microspheres could be oxidized to seleninic acid by H2O2 which can catalyze the oxidation of acrolein. The oxidized DSe-PS microspheres exhibited higher catalytic activity and selectivity to methyl acrylate in a model oxidation of acrolein.

Tunable synthesis of chalcophosphinic amides and tertiary phosphinates using tert-butyl N,N-dialkylperoxyamidate

The tunable amidation and esterification of phosphine chalcoxide have been developed, in which tert-butyl N,N-dialkylperoxyamidate plays a dual role as a secondary amine and a tertiary alcohol precursor.