Convenient One-Pot Synthesis of α-Amino Phosphonates in Water Usingp-Toluenesulfonic Acid as Catalyst for the Kabachnik-Fields Reaction

Microwave-Assisted Synthesis of Aminophosphonic Derivatives and Their Antifungal Evaluation against Lomentospora prolificans

Lomentospora prolificans is a pathogenic and multidrug-resistant fungus that can infect both immunocompetent and immunocompromised patients, with mortality rates up to 87%. The World Health Organization (WHO) included this fungal species in its first list of 19 priority fungal pathogens, which focused on fungal pathogens that can cause invasive acute and subacute systemic fungal infections. Therefore, there is a growing interest in finding new therapeutic alternatives. In this work, the synthesis of twelve α-aminophosphonates by the microwave-assisted Kabachnik-Fields reaction and twelve α-aminophosphonic acids by a monohydrolysis reaction is reported. All compounds were evaluated by the agar diffusion method as a preliminary screening in comparison with voriconazole, showing inhibition halos for compounds 7, 11, 13, 22 and 27. The five active compounds in the preliminary tests were evaluated against five strains of L. prolificans following protocol M38-A2 from CLSI. The results showed that these compounds exhibit antifungal activity in the concentration range of 900->900 μg/mL. Cytotoxicity against healthy COS-7 cells was also evaluated by the MTT assay, and it was shown that compound 22 was the least cytotoxic, with a viability of 67.91%, comparable to the viability exhibited by voriconazole (68.55%). Docking studies showed that the possible mechanism of action of the active compounds could be through the inhibition of the enzyme lanosterol-14-alpha-demethylase in an allosteric hydrophobic cavity.

Mechanistic study of Hg(II) interaction with three different α-aminophosphonate adsorbents: Insights from batch experiments and theoretical calculations

Herein, efficient and potential chelating α-aminophosphonate based sorbents (AP-) derived from three different amine origins (aniline/anthranilic acid/O-phenylenediamine) to form AP-H, carboxylated and aminated enhanced aminophosphonate as AP-H, AP-COOH, and AP-NH₂ were synthesized via a facile method. The structure of the synthesized sorbents was elucidated using different techniques; elemental analysis (CHNP/O), FT-IR, NMR (¹H-, ¹³C and ³¹P NMR), TGA and BET. The fabricated sorbents were exploited for Hg(II) removal from aqueous solution via sorption properties. Isotherm fitted by Langmuir equation: the maximum sorption capacities at optimum pH 5.5, and T:25 ± 1 °C, were found to be 1.33, 1.23, and 1.15 mmol Hg g^-1 for AP-COOH, AP-NH₂, AP-H, respectively, which is roughly correlated with the active sites density and the hard/soft characteristics of adsorbents' reactive groups. Metal-ligand binding affinities are qualitatively rationalized in terms of hard and soft acids and bases (HSAB) theory. The interaction of Hg(II) (soft) has a stronger affinity to AP-COOH can be considered a softer base compared with reference material (AP-H) over than AP-NH₂ (hard). This sequence result showed opposite trends consistent with their reciprocal properties according to the steric effect modulates and the specific surface area. Thermodynamics analysis for absolute values of ΔH°, ΔS° and ΔG° afford the selectivity towards Hg(II) sorption with the following order: AP-COOH > AP-NH₂ >AP-H. Elution and regeneration was carried out by HCl solution and recycled for a minimum of five cycles, the sorption and desorption efficiencies are greater than 91%. Such sorbents exhibit good durability, stability and promising potential for Hg(II) removal. Finally, a new modelling technique for quantitative non-linear description and comparison of equivalent geographical positions in 3D space of extended relationships. Exothermic and spontaneous behavior were observed using a proposed Floatotherm that included the Van't Hoff parameters model.

Synthesis of α-Aminophosphonates and Related Derivatives; the Last Decade of the Kabachnik-Fields Reaction

The Kabachnik-Fields reaction, comprising the condensation of an amine, oxo compound and a P-reagent (generally a >P(O)H species or trialkyl phosphite), still attracts interest due to the challenging synthetic procedures and the potential biological activity of the resulting α-aminophosphonic derivatives. Following the success of the first part (Molecules 2012, 17, 12821), here we summarize the synthetic developments in this field accumulated in the last decade. The procedures compiled include catalytic accomplishments as well as catalyst-free and/or solvent-free "greener" protocols. The products embrace α-aminophosphonates, α-aminophosphinates, and α-aminophosphine oxides along with different bis derivatives from the double phospha-Mannich approach. The newer developments of the aza-Pudovik reactions are also included.

Highly Selective Separation Intermediate-Size Anionic Pollutants from Smaller and Larger Analogs via Thermodynamically and Kinetically Cooperative-Controlled Crystallization

Selective separation of organic species, particularly that of intermediate-size ones from their analogs, remains challenging because of their similar structures and properties. Here, a novel strategy is presented, cooperatively (thermodynamically and kinetically) controlled crystallization for the highly selective separation of intermediate-size anionic pollutants from their analogs in water through one-pot construction of cationic metal-organic frameworks (CMOFs) with higher stabilities and faster crystallization, which are based on the target anions as charge-balancing anions. 4,4'-azo-triazole and Cu2+ are chosen as suitable ligand and metal ion for CMOF construction because they can form stronger intermolecular interaction with p-toluenesulfonate anion (Ts-) compared to its analogs. For this combination, a condition is established, under which the crystallization rate of a Ts--based CMOF is remarkably high while those of analog-based CMOFs are almost zero. As a result, the faster crystallization and higher stability cooperatively endow the cationic framework with a close-to-100% selectivity for Ts- over its analogs in two-component mixtures, and this preference is retained in a practical mixture containing more than seven competing (analogs and inorganic) anions. The nature of the free Ts- anion in the cationic framework also allows the resultant CMOF to be recyclable via anion exchange.

2-[Anilino(diphenylphosphoryl)methyl]phenol from a three-component Kabachnik-Fields reaction

The title compound, C25H22NO2P, was synthesized in high yield by a three-component Kabachnik-Fields reaction of diphenylphosphine oxide, salicylaldehyde and aniline in dry toluene at room temperature. It precipitates as racemic crystals, in which strong hydrogen bonds between the hydroxy group and the P=O group of a neighbouring molecule form one-dimensional heterochiral chains along the crystallographic a axis, with an O···O separation of 2.568 (2) Å. The pseudo-tetrahedral environment of the P atom is distorted, with O-P-C bond angles significantly larger than the C-P-C angles.