LaCl3.7H2O: An efficient catalyst for the synthesis of phosphinates (Michaelis–Arbuzov reaction) under neat conditions and their potential antimicrobial activity

Synthesis of Phosphorus(V)-Substituted Six-Membered N-Heterocycles: Recent Progress and Challenges

Heterocycles functionalized with pentavalent phosphorus are of great importance since they include a great variety of biologically active compounds and pharmaceuticals, advanced materials, and valuable reactive intermediates for organic synthesis. Significant progress in synthesis of P(O)R2-substituted six-membered heterocycles has been made in the past decade. This review covers the synthetic strategies towards aromatic monocyclic six-membered N-heterocycles, such as pyridines, pyridazines, pyrimidines, and pyrazines bearing phosphonates and phosphine oxides, which were reported from 2012 to 2022.

Improvements, Variations and Biomedical Applications of the Michaelis-Arbuzov Reaction

Compounds bearing the phosphorus–carbon (P–C) bond have important pharmacological, biochemical, and toxicological properties. Historically, the most notable reaction for the formation of the P–C bond is the Michaelis–Arbuzov reaction, first described in 1898. The classical Michaelis–Arbuzov reaction entails a reaction between an alkyl halide and a trialkyl phosphite to yield a dialkylalkylphosphonate. Nonetheless, deviations from the classical mechanisms and new modifications have appeared that allowed the expansion of the library of reactants and consequently the chemical space of the yielded products. These involve the use of Lewis acid catalysts, green methods, ultrasound, microwave, photochemically-assisted reactions, aryne-based reactions, etc. Here, a detailed presentation of the Michaelis–Arbuzov reaction and its developments and applications in the synthesis of biomedically important agents is provided. Certain examples of such applications include the development of alkylphosphonofluoridates as serine hydrolase inhibitors and activity-based probes, and the P–C containing antiviral and anticancer agents.

Heterogeneous catalyst SiO2-LaCl3·7H2O: characterization and microwave-assisted green synthesis of α-aminophosphonates and their antimicrobial activity

Silica-supported lanthanum (III) chloride (SiO₂-LaCl₃·7H₂O) was prepared and characterized by infrared spectroscopy, X-ray diffraction analysis, scanning electron microscope, energy-dispersive X-ray spectroscopy, thermogravimetric analysis and differential thermal analysis techniques. The catalytic activity of this silica-supported lanthanum (III) chloride was investigated in a one-pot three-component Kabachnik-Fields reaction. A library of new α-aminophosphonates was prepared employing various benzothiazole and thiadiazole amines, different substituted aldehydes and diethylphosphite under solvent-free conditions using conventional/microwave methods with good to excellent yields (85-97%). The advantages of this catalyst are that it is environmentally benign, economically inexpensive, and easy to prepare, gives high yields and high purity is less time-consuming, offers easy purification is reusable and enables products to be obtained by simple recrystallization without column chromatography.