Reinvestigation of the iodine-mediated phosphoramidation reaction of amines and P(OR)3 and its synthetic applications

31P Nuclear Magnetic Resonance Spectroscopy for Monitoring Organic Reactions and Organic Compounds

31P NMR spectroscopy is a consolidated tool for the characterization of organophosphorus compounds and, more recently, for reaction monitoring. The evolution of organic synthesis, mainly due to the combination of elaborated building blocks with enabling technologies, generated great challenges to understand and to optimize the synthetic methodologies. In this sense, 31P NMR experiments also became a routine technique for reaction monitoring, accessing products and side products yields, chiral recognition, kinetic data, intermediates, as well as basic organic parameters, such as acid-base and hydrogen-bonding. This review deals with these aspects demonstrating the essential role of the 31P NMR spectroscopy. The recent publications (the last ten years) will be explored, discussing the experiments of 31P NMR and the strategies accomplished to detect and/or quantify distinct organophosphorus molecules, approaching reaction mechanism, stability, stereochemistry, and the utility as a probe.

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.

Visible-Light-Driven Organophotocatalyzed Mono-, Di-, and Tri-C(sp3)-H Alkylation of Phosphoramides

A photocatalytic metal-free, visible-light-driven, highly atom-economic, direct multiple α-C(sp³)-H alkylation of phosphoramides and thiophosphoramides is demonstrated under environmentally benign conditions. Economically viable and commercially available Eosin-Y is used as an HAT photocatalyst for mono-α-C(sp³)-H alkylation of phosphoramide derivatives. Remarkably, di- and tri-C(sp³)-H alkylation of phosphoramides and thiophosphoramides using an acridinium photocatalyst is reported with good yield and selectivity. Mechanistic studies reveal that monoalkylation of phosphoramides by Eosin-Y follows the HAT mechanism, whereas di- and tri-C(sp³)-H alkylation by the acridinium photocatalyst follows the SET mechanism.

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.

Efficient Synthesis of Phosphonamidates through One-Pot Sequential Reactions of Phosphonites with Iodine and Amines

A one-pot sequential strategy to construct phosphonamidates has been developed by generating phosphonites in situ from arylmagnesium bromides and triethyl phosphite followed by treatment with iodine and amines. A variety of phosphonamidates were obtained with good to excellent yields at room temperature from easily available materials.

Opening up the Toolbox: Synthesis and Mechanisms of Phosphoramidates

This review covers the main synthetic routes to and the corresponding mechanisms of phosphoramidate formation. The synthetic routes can be separated into six categories: salt elimination, oxidative cross-coupling, azide, reduction, hydrophosphinylation, and phosphoramidate-aldehyde-dienophile (PAD). Examples of some important compounds synthesized through these routes are provided. As an important class of organophosphorus compounds, the applications of phosphoramidate compounds, are also briefly introduced.