Environmentally benign synthesis and antimicrobial study of novel chalcogenophosphates

Construction of Phosphorothiolated 2-Pyrrolidinones via Photoredox/Copper-Catalyzed Cascade Radical Cyclization/Phosphorothiolation

A photoredox/copper-catalyzed cascade radical cyclization/phosphorothiolation reaction of N-allylbromoacetamides and P(O)SH compounds has been established. A broad range of novel nonfluorine- or difluoro-substituted 2-pyrrolidinones bearing the C(sp3)-SP(O)(OR)2 moiety can be conveniently constructed in moderate to good yields under mild conditions. Importantly, most of the tested phosphorothiolated 2-pyrrolidinones showed potent inhibitory effects toward both AChE and BChE.

NaOAc-Assisted Aerobic Oxidation Protocol for the Synthesis of Pentacoordinate Chalcogenyl Spirophosphoranes with P-Se/P-S Bonds under Open Air

The NaOAc-assisted aerobic oxidation reaction of pentacoordinate hydrospirophosphoranes and dichalcogenyl compounds with open air as a green oxidant has been developed under mild conditions. A series of novel pentacoordinate spirophosphoranes with P-Se/P-S bonds were synthesized in excellent yields. The reaction mechanism was determined by 31P nuclear magnetic resonance tracing experiments, high-resolution mass spectrometry tracing experiments, and X-ray diffraction analysis. The method features a broad substrate scope, good functional group tolerance, and a high degree of atomic utilization and is meaningful for the synthesis of bioactive chalcogenphosphate compounds with chalcogen and phosphorus moieties.

Organoselenium Compounds: Chemistry and Applications in Organic Synthesis

Selenium, originally described as a toxin, turns out to be a crucial trace element for life that appears as selenocysteine and its dimer, selenocystine. From the point of view of drug developments, selenium-containing drugs are isosteres of sulfur and oxygen with the advantage that the presence of the selenium atom confers antioxidant properties and high lipophilicity, which would increase cell membrane permeation leading to better oral bioavailability. In this article, we have focused on the relevant features of the selenium atom, above all, the corresponding synthetic approaches to access a variety of organoselenium molecules along with the proposed reaction mechanisms. The preparation and biological properties of selenosugars, including selenoglycosides, selenonucleosides, selenopeptides, and other selenium-containing compounds will be treated. We have attempted to condense the most important aspects and interesting examples of the chemistry of selenium into a single article.

Catalyst-free thiophosphorylation of in situ formed ortho-quinone methides

A metal-, chloride reagent and base-free thiophosphorylation reaction of in situ formed ortho-quinone methide (o-QM) to synthesize functionalized thiophosphates has been developed. The reaction is an atom-economical process, producing water as the sole byproduct. (EtO)₂P(O)SH functions as both a Brønsted acid and nucleophilic thiolate to produce the o-QM intermediate and the thiophosphate product, respectively. The aza o-QMs were also successfully thiophosphorylated in the presence of catalytic TsOH to form sulfonamido thiophosphates.

Photoinduced Decarboxylative Phosphorothiolation of N-Hydroxyphthalimide Esters

A visible-light-induced protocol for the synthesis of phosphorothioates is developed by employing the Ir-catalyzed decarboxylative phosphorothiolation of N-hydroxyphthalimide esters. This novel synthesis method utilizes carboxylic acids as raw material, which is stable, cheap, and commercially available. Scope studies show that this reaction has good compatibility of functional groups. Notably, both the synthesis of steric hindrance phosphorothioates and the later modification of some bioactive compounds are successfully achieved.

A greener protocol for the synthesis of phosphorochalcogenoates: Antioxidant and free radical scavenging activities

In this contribution, a metal- and base-free protocol has been developed for the synthesis of phosphorochalcogenoates (Se and Te) by using DMSO as solvent at 50 °C. A variety of phosphorochalcogenoates were prepared from diorganyl dichalcogenides and H-phosphonates, leading to the formation of a Chal-P(O) bond, in a rapid procedure with good to excellent yields. A full structural elucidation of products was accessed by 1D and 2D NMR, IR, CGMS, and HRMS analyses, and a stability evaluation of the phosphorochalcogenoates was performed for an effective operational description of this simple and feasible method. Typical ⁷⁷Se{¹H} (δ_Se = 866.0 ppm), ¹²⁵Te{¹H} (δ_Te = 422.0 ppm) and ³¹P{¹H} (δ_P = -1.0, -13.0 and -15.0 ppm) NMR chemical shifts were imperative to confirm the byproducts, in which this stability study was also important to select some products for pharmacological screening. The phosphorochalcogenoates were screened in vitro and ex vivo tests for the antioxidant potential and free radical scavenging activity, as well as to investigation toxicity in mice through of the plasma levels of markers of renal and hepatic damage. The pharmacological screening of phosphorochalcogenoates indicated that compounds have antioxidant propriety in different assays and not changes plasma levels of markers of renal and hepatic damage, with excision of 3g compound that increased plasma creatinine levels and decreased plasma urea levels when compared to control group in the blood mice. Thus, these compounds can be promising synthetic antioxidants that provide protection against oxidative diseases.

Highly atom-economical, catalyst-free, and solvent-free phosphorylation of chalcogenides

Silica gel promoted, catalyst-free and solvent-free S-P, Se-P and Te-P bond formations are described. A variety of disulfides coupled with diarylphosphine oxides provide the corresponding phosphinothioates in excellent yields. For the first time, diselenides and ditellurides reacted with dialkyl phosphites under catalyst-free conditions to provide the corresponding phosphoroselenoates and phosphorotelluroates, respectively, in good to excellent yields.

Arylation of Axially Chiral Phosphorothioate Salts by Dinuclear PdI Catalysis

S-aryl phosphorothioates are privileged motifs in pharmaceuticals, agrochemicals, and catalysts; yet, the challenge of devising a straightforward synthetic route to enantioenriched S-aryl phosphorothioates has remained unsolved to date. We demonstrate herein the first direct C-SP(=O)(OR')(OR'') coupling of diverse and chiral phosphorothioate salts with aryl iodides, enabled by an air- and moisture-stable PdI dimer. Our mechanistic and computational data suggest distinct dinuclear PdI catalysis to be operative, which allows for operationally simple couplings with broad scope and full retention of stereochemistry.

Atom-economical selenation of electron-rich arenes and phosphonates with molecular oxygen at room temperature

An environmentally benign selenation of electron-rich arenes and phosphonates is developed adopting a novel recycle–reuse–reduce strategy for selenol by oxygen.

Magnetically recyclable Cu-BTC@Fe3O4 composite-catalyzed C(aryl)–S–P bond formation using aniline, P(O)H compounds and sulfur powder

A magnetically recyclable Cu-BTC@Fe₃O₄-catalyzed synthesis of S-aryl phosphorothioates using aniline as the aryl source and sulfur powder as the sulfur source has been developed.

Peroxide-free synthesis of benzo[b][1,4]thiazine 1,1-dioxides and their antimicrobial study

A peroxide-free reaction protocol for the oxidation of benzo[b][1,4]thiazines has been developed under mild conditions. An in vitro antimicrobial study along with statistical analysis, MIC study and bacterial killing kinetics were investigated.

Catalyst-free selenylation of imidazoheterocycles

A simple, efficient, and practical method for the phenylselenylation of imidazo[1,2-a]pyridines via electrophilic substitution employing readily available phenylselenium bromide has been developed in aqueous media at room temperature.