Iodine catalyzed solvent-free cross-dehydrogenative coupling of arylamines and H-phosphonates for the synthesis of N-arylphosphoramidates under atmospheric conditions

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.

Revisiting applications of molecular iodine in organic synthesis

Molecular iodine contributes significantly to organic transformations in synthetic organic chemistry. It works effectively due to its mild Lewis acidic character, ability as an oxidizing agent, good moisture stability, and easy availability.

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.

Practical Synthesis of Phosphinic Amides/Phosphoramidates through Catalytic Oxidative Coupling of Amines and P(O)-H Compounds

Herein, we report a highly efficient ZnI₂ -triggered oxidative cross-coupling reaction of P(O)-H compounds and amines. This operationally simple protocol provides unprecedented generic access to phosphinic amides/phosphoramidate derivatives in good yields and short reaction time. Besides, the reaction proceeds under mild conditions, which avoids the use of hazardous reagents, and is applicable to scale-up syntheses as well as late-stage functionalization of drug molecules. The stereospecific coupling is also achieved from readily available optically enriched P(O)-H compounds.

Transition-metal-free amination phosphoryl azide for the synthesis of phosphoramidates

A facile and efficient approach to phosphoramidates was developed via amination of phosphoryl azides. A variety of phosphoramidates were obtained in one step with good to excellent yields under a mild reaction system. The process uses easily available amines as a N source and offers a new opportunity for P-N bond formation.

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

A systematic study on the iodine-mediated phosphoramidation reaction of amines and trialkyl phosphites was conducted, which not only disclosed the factors affecting the reaction but also revealed that it could proceed smoothly in CH2Cl2 at room temperature in open air. Using this method, various phosphoramidates with different aliphatic amines and aromatic amines were synthesized in good to excellent yields. Our present investigation shows that this underused method is actually a mild, practical and general way to synthesize phosphoramidates and will have wide applications.

One-Pot Synthesis of P(O)-N Containing Compounds Using N-Chlorosuccinimide and Their Influence in Thermal Decomposition of PU Foams

Synthesis of intermediate containing P(O)-Cl bonds is the key to converting P(O)-H bonds to P(O)-N. In this work we have performed chlorination reactions of different H-phosphinates and H-phosphonates using N-chlorosuccinimide as an environmentally-benign chlorinating agent. The chlorination reaction showed high yield and high selectivity for transformation of P(O)-H bonds into P(O)-Cl analogues, resulting in an easily separable succinimide as the by-product. Using a one-pot synthesis methodology, we have synthesized a series of P(O)-N containing derivatives whose synthesis was found to be dependent on the reaction solvents and the starting materials. The synthesized P(O)-N compounds were incorporated in flexible polyurethane foam (FPUF) and screened for their influence in thermal decomposition of FPUFs using thermogravimetric analysis (TGA) and a microscale combustion calorimeter (MCC). All solid P(O)-N compounds influenced the first-stage decomposition of FPUFs, which resulted in an accelerated decomposition or temporary stabilization of this stage. However, the liquid P(O)-N derivatives volatilize at an earlier stage and could be active in the gas phase. In addition, they also work in condensed phase via acid catalyzed decomposition for FPUFs.

Direct intramolecular amination of tryptophan esters to prepare pyrrolo[2,3-b]indoles

A metal-free iodine-catalyzed intramolecular amination has been developed for the practical synthesis of pyrrolo[2,3-b]indoles from readily available tryptophan esters. The transformation has been applied to a wide array of substrates and can be performed on gram scale under very mild conditions.

Cu(ii)-catalyzed cross-dehydrogenative coupling reaction of N′-acyl arylhydrazines and phosphites

A novel Cu(ii)-catalyzed cross-dehydrogenative coupling reaction of N′-aryl acylhydrazines and dialkyl phosphites has been developed for the synthesis of phosphorylhydrazides by using NMO as an external oxidant and AgNO₃ as additive.

Recent advances in H-phosphonate chemistry. Part 1. H-phosphonate esters: synthesis and basic reactions

This review covers recent progress in the preparation of H-phosphonate mono- and diesters, basic studies on mechanistic and stereochemical aspects of this class of phosphorus compounds, and their fundamental chemistry in terms of transformation of P-H bonds into P-heteroatom bonds. Selected recent applications of H-phosphonate derivatives in basic organic phosphorus chemistry and in the synthesis of biologically important phosphorus compounds are also discussed.

Intramolecular oxidative coupling: I2/TBHP/NaN3-mediated synthesis of benzofuran derivatives

A novel intramolecular oxidative coupling reaction has been established to prepare benzofuran derivatives via direct C(sp²)–H functionalization for the formation of C–O bonds. This transformation is mediated by I₂/TBHP/NaN₃ under metal-free conditions and a catalytic amount of NaN₃ plays a crucial role in the reaction.