Hydrophosphonylation of alkenes or nitriles by double radical transfer mediated by titanocene/propylene oxide

Efficient synthesis of α-amino-vinylphosphine oxides from alkyl nitriles via manganese-catalyzed phosphinoenamination

A protocol for the synthesis of α-amino-vinylphosphine oxides by phosphinoenamination reaction between alkyl nitriles and phosphine oxides was developed. The combination of Mn(OAc)2 as a Lewis acid and guanidine as a Lewis base was found to be an efficient catalytic system for this reaction. A series of alkyl nitriles and phosphine oxides are compatible with this conversion, furnishing the desired products in up to 95% yield under mild conditions. Furthermore, this method demonstrates the capability of gram-scale synthesis.

One-Pot Synthesis of α-Amino Bisphosphonates from Nitriles via Tf2O/HC(OR)3-Mediated Interrupted Ritter-Type Reaction

A versatile synthesis of α-amino bisphosphonates has been achieved through one-pot interrupted Ritter-type reaction under mild conditions. The reactive Ritter intermediate nitrilium is in situ generated by treatment of nitrile with readily accessible Tf₂O/HC(OR¹)₃, which is trapped by phosphite ester to deliver the desired product. This protocol is efficient, scalable, and well compatible with a broad scope of substrates. In addition, plentiful characteristic J_P-C couplings including unusual five-bond long-range ⁵J_P-C and ³J_P-C across quaternary carbon and hetero (N) atoms were observed in ¹³C NMR spectra.

One-Pot and Catalyst-Free Transformation of N-Protected 1-Amino-1-Ethoxyalkylphosphonates into Bisphosphonic Analogs of Protein and Non-Protein α-Amino Acids

Herein, we describe the development of one-pot transformation of α-ethoxy derivatives of phosphorus analogs of protein and non-protein α-amino acids into biologically important N-protected 1-aminobisphosphonates. The proposed strategy, based on the three-component reaction of 1-(N-acylamino)-1-ethoxyphosphonates with triphenylphosphonium tetrafluoroborate and triethyl phosphite, facilitates good to excellent yields under mild reaction conditions. The course of the reaction was monitored by ³¹P NMR spectroscopy, allowing the identification of probable intermediate species, thus making it possible to propose a reaction mechanism. In most cases, there is no need to use a catalyst to provide transformation efficiency, which increases its attractiveness both in economic and ecological terms. Furthermore, we demonstrate that the one-pot procedure can be successfully applied for the synthesis of structurally diverse N-protected bisphosphonic analogs of α-amino acids. As shown, the indirect formation of the corresponding phosphonium salt as a reactive intermediate during the conversion of 1-(N-acylamino)-1-ethoxyphosphonate into a 1-aminobisphosphonate derivative is a crucial component of the developed methodology.

Hydroxy- and Amino-Phosphonates and -Bisphosphonates: Synthetic Methods and Their Biological Applications

Phosphonates and bisphosphonates are stable analogs of phosphates and pyrophosphates that are characterized by one and two carbon–phosphorus bonds, respectively. Among the various phosphonates and bisphosphonates, hydroxy and amino substitutes are of interest as effective in medicinal and industrial chemistry. For example, hydroxy bisphosphonates have proven to be effective for the prevention of bone loss, especially in osteoporotic disease. On the other hand, different substitutions on the carbon atom connected to phosphorus have led to the synthesis of many different hydroxy- and amino-phosphonates and -bisphosphonates, each with its distinct physical, chemical, biological, therapeutic, and toxicological characteristics. Dialkyl or aryl esters of phosphonate and bisphosphonate compounds undergo the hydrolysis process readily and gave valuable materials with wide applications in pharmaceutical and agriculture. This review aims to demonstrate the ongoing preparation of various classes of hydroxy- and amino-phosphonates and -bisphosphonates. Furthermore, the current review summarizes and comprehensively describes articles on the biological applications of hydroxyl- and amino-phosphonates and -bisphosphonates from 2015 until today.

Nickel-Catalyzed 1,1-Dihydrophosphinylation of Nitriles with Phosphine Oxides

Treatment of phosphine oxides with nitriles usually furnishes 1,2-dihydrophosphinylation products. Herein, we developed a nickel-catalyzed 1,1-dihydrophosphinylation of nitriles with phosphine oxides to access primary amines. This reaction proceeded smoothly under very mild conditions. A series of nitriles and phosphine oxides were compatible with this conversion, and the desired products were obtained in moderate to good yields.

α-(Imino)pyridyldifluoroethyl Phosphonates: Novel Promising Building Blocks in Synthesis of Biorelevant Aminophosphonic Acids Derivatives

A convenient synthetic approach to previously unknown NH-iminophosphonates bearing 2-, 3-, and 4-pyridyldifluoromethyl groups at the imine carbon atom was developed. The synthetic potential of these novel building blocks was demonstrated by their conversion into highly functionalized acyclic and heterocyclic aminophosphonates and phosphonic acids combining in their structure biorelevant aminophosphonic fragment, difluoromethyl group, and pyridyl, piperidyl, thiazolidin-4-one, or thiazidinan-4-one heterocyclic moieties in a single molecular platform.

Synthetic Procedures Leading towards Aminobisphosphonates

Growing interest in the biological activity of aminobisphosphonates has stimulated the development of methods for their synthesis. Although several general procedures were previously elaborated to reach this goal, aminobisphosphonate chemistry is still developing quite substantially. Thus, innovative modifications of the existing commonly used reactions, as well as development of new procedures, are presented in this review, concentrating on recent achievements. Additionally, selected examples of aminobisphosphonate derivatization illustrate their usefulness for obtaining new diagnostic and therapeutic agents.

Recent developments in alkene hydro-functionalisation promoted by homogeneous catalysts based on earth abundant elements: formation of C-N, C-O and C-P bond

This Perspective article provides an overview of the recent advancements in the field of intra- and inter-molecular C-N, C-O and C-P bond formation by hydroamination, hydroalkoxylation, hydrophosphination, hydrophosphonylation or hydrophosphinylation of unactivated alkenes, including allenes, 1,3-dienes and strained alkenes, promoted by (chiral) homogeneous catalysts based on earth abundant elements of the s and p blocks, the first row transition metals and the rare-earth metals. The relevant literature from 2009 until late 2014 has been covered.

Probing the reactivity of H-phosphonate derivatives for the hydrophosphonylation of various alkenes and alkynes under free-radical conditions

Hydrophosphonylation of various alkenes and alkynes is reported using DPAP as a photoinitiator under UV irradiation.

Validating the alkene and alkyne hydrophosphonylation as an entry to organophosphonates

The hydrophosphonylation of terminal alkenes and alkynes by H-phosphonates affords Markovnikov and/or anti-Markovnikov adducts depending on the catalyst (a metal or a radical initiator) and the reaction conditions.