Synthesis of Unsymmetrical Tertiary Phosphine Oxides via Sequential Substitution Reaction of Phosphonic Acid Dithioesters with Grignard Reagents

Tf2O/DMSO-Promoted Umpolung Phosphorylation for C(sp2)-P or C(sp3)-P Bond Formation

We have developed an umpolung method utilizing the Tf2O/DMSO-based system for C(sp2)-P bond or C(sp3)-P bond formation. This method employs both P(O)-H and P(O)-OH compounds as phosphorus sources and demonstrates excellent compatibility with a wide range of Grignard reagents. Without the requirement of precious transition metals or additives, this one-pot protocol provides a practical and efficient synthetic pathway to a variety of aryl and alkyl phosphine oxides. The broad substrate scope and diverse synthetic applications highlight the practical utility of this method.

Closing the Loop: Low-Waste Phosphorus Functionalization Enabled by Simple Disulfides

Useful monophosphorus products are obtained from both white and red phosphorus via a simple strategy involving initial oxidation by aryl disulfides followed by quenching with nucleophiles. Direct transformations of elemental phosphorus are usually very challenging, forcing chemists to instead rely on inefficient and hazardous multi-step methods. However, here they are achieved using inexpensive and easy-to-handle reagents, providing access to diverse P-C, P-N and P-O bonded products in good yields. By isolating the thiolate byproducts of these reactions, a simple, closed loop can be achieved that produces only minimal, benign waste byproducts, in contrast to other direct methods. This closed loop can even be elaborated into a true (electro)catalytic cycle, which is extremely rare in the field of elemental phosphorus functionalization.

DMSO-Catalyzed Double P-O Bond or Double P-S Bond Formations of Phosphinic Acids

A DMSO-catalyzed double P-O bond or double P-S bond formation of phosphinic acid with an O- or S-containing nucleophile has been developed. Under metal-free and mild conditions, this simple procedure provides a compatible and rapid access to a variety of phosphonates and dithiophosphates. The DFT calculation of stabilization energy (SE) and the mechanism studies demonstrated that the "just right" Lewis base property and the relatively "soft" interaction strength with the phosphenium-dication ensure the unique catalytic activity of DMSO in this transformation.

A Modular Three-Component Approach for Site-selective Tandem Arene Thiophosphorylation

Thiophosphates serve as pivotal reagents within the realms of both organic and inorganic synthesis, with their most notable applications observed in agricultural chemistry. This manuscript delineates a modular three-component synthetic strategy for site-selective arene C-H thiophosphorylation with thianthrenium salt, 1,4-diazabicyclo[2.2.2]octane-sulfur dioxide (DABSO), and diarylphosphine oxides as substrates. This approach facilitates the metal-free and green synthesis of a diverse spectrum of S-aryl phosphorothioates through C-H functionalization and late-stage modification showcasing practicality and broad applicability.

Photochemical halogen-bonding assisted carbothiophosphorylation reactions of alkenyl and 1,3-dienyl bromides

Herein, we present a synthetic procedure for the facile and general preparation of novel S-alkenyl and dienyl phosphoro(di)thioates for the first time. Extensive mechanistic investigations support that the reactions rely on a photochemical excitation of a halogen-bonding complex, formed with a phosphorothioate salt and an alkenyl or dienyl bromide, which light-induced fragmentation leads to the formation of the desired products through a radical-based pathway. The substrate scope is broad and exhibits a wide functional group tolerance in the formation of the final compounds, including molecules derived from natural products, all with unknown and potentially interesting biological properties. Eventually, a very efficient continuous flow protocol was developed for the upscale of these reactions.

Metal-Free S-Arylation of Phosphorothioate Diesters and Related Compounds with Diaryliodonium Salts

We developed a direct metal-free S-arylation of phosphorothioate diesters using diaryliodonium salts. The method allows for the preparation under simple conditions of a broad range of S-aryl phosphorothioates, including complex molecules (e.g., dinucleotide or TADDOL derivatives), as well as other related organophosphorus compounds arylated at a chalcogen. The reaction proceeds with a full retention of the stereogenic center at the phosphorus atom, opening convenient access to P-chiral products. The mechanism of the reaction was established using DFT calculations.

Palladium-Catalyzed C-P(III) Bond Formation by Coupling ArBr/ArOTf with Acylphosphines

Palladium-catalyzed C-P bond formation reaction of ArBr/ArOTf using acylphosphines as differential phosphination reagents is reported. The acylphosphines show practicable reactivity with ArBr and ArOTf as the phosphination reagents, though they are inert to the air and moisture. The reaction affords trivalent phosphines directly in good yields with a broad substrate scope and functional group tolerance. This reaction discloses the acylphosphines' capability as new phosphorus sources for the direct synthesis of trivalent phosphines.

Nucleophilic transformations of azido-containing carbonyl compounds via protection of the azido group

Nucleophilic transformations of azido-containing carbonyl compounds are discussed. The phosphazide formation from azides and di(tert-butyl)(4-(dimethylamino)phenyl)phosphine (Amphos) enabled transformations of carbonyl groups with nucleophiles such as lithium aluminum hydride and organometallic reagents. The good stability of the phosphazide moiety allowed us to perform consecutive transformations of a diazide through triazole formation and the Grignard reaction.

Regioselective and stereoselective cleavages of P–S/C–S bonds by lithium and the formation of P-stereogenic functional phosphine derivatives

Various menthyl-containing phosphinothioates were prepared.

Radical Arylation of Triphenyl Phosphite Catalyzed by Salicylic Acid: Mechanistic Investigations and Synthetic Applications

A straightforward and scalable methodology to synthesize diphenyl arylphosphonates at 20 °C within 1-2 h is reported using inexpensive SA as the catalytic promoter of the reaction. Mechanistic investigations suggest that the reaction proceeds via radical-radical coupling, consistent with the so-called persistent radical effect. The reaction tolerated a wide range of functional groups and heteroaromatic moieties. The synthetic usefulness and the unique reactivity of the obtained phosphonates were demonstrated in different one-step transformations.

Robust synthesis of NIR-emissive P-rhodamine fluorophores

P-Rhodamines were accessed by implementing a robust three step sequence consisting of (i) addition of m-metallated anilines to dichlorophosphine oxides, (ii) selective dibromination, and (iii) cyclization of the diaryllithium reagents derived from the dibromides to form the dihydroacridophosphine core of P-rhodamines. A modified route was developed to produce non-symmetric P-rhodamines. A library of prepared P-rhodamines provides first insight into dependence of fluorophore properties on the structure of P-rhodamines. A P-rhodamine with highest batochromic shifts and quantum yields in the class was identified.

Synthesis of benzyl sulfidesviasubstitution reaction at the sulfur of phosphinic acid thioesters

An ambident electrophilicity of phosphinic acid thioesters is disclosed. Unexpected carbon–sulfur bond formation took place in the reaction between phosphinic acid thioesters and benzyl Grignard reagents to provide various benzyl sulfides.

Flexible Synthesis of Phosphoryl-Substituted Imidazolines, Tetrahydropyrimidines, and Thioamides by Sulfur-Mediated Processes

The solvent-free sulfur-mediated reactions of phosphinic chlorides with alkyl diamines were developed for the practical synthesis of unknown phosphoryl-substituted 4,5-dihydro-1H-imidazoles, 1,4,5,6-tetrahydropyrimidines, and thioamides. Their good tolerance to functional groups, broad substrate scope, and easy scalability were shown. The chemoselective preparation of a variety of phosphoryl-substituted bis(thioamides) was accomplished via the adjustment of a solvent.

Staudinger reaction using 2,6-dichlorophenyl azide derivatives for robust aza-ylide formation applicable to bioconjugation in living cells

Efficient formation of water- and air-stable aza-ylides has been achieved by the Staudinger reaction. The reaction proceeds rapidly and has been successfully applied to chemical modification of proteins in living cells.

Dearylation of arylphosphine oxides using a sodium hydride–iodide composite

A new protocol for the dearylative functionalization of arylphosphine oxides was developed using NaH in the presence of LiI.