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The increasing demand to provide sustainably produced plastic materials requires, a.o., the development of biobased flame retardants (FRs) for applications where flame retardancy is essential. To meet those challenging new sustainability requirements, a set of novel phosphorus-containing cellulose esters were synthesized by an efficient two-step procedure. In the first step, cellulose was treated with acrylic anhydride to synthesize acrylate-functionalized cellulose esters—more specifically, cellulose acrylate butyrate (CeAcBu) and propionate (CeAcPr). Subsequently, phosphorylated anhydro erythritol (PAHE), synthesized from the sugar alcohol erythritol, was added to the acrylate-functionalized cellulose esters via Phospha-Michael addition. For comparison a cellulose ester based on 6H-Dibenzo[c,e][1,2]oxaphosphorin-6-on (DOPO) was prepared analogously. The acrylate-functionalized cellulose esters and novel FRs were characterized by NMR spectroscopy. TGA investigations of PAHE-functionalized CeAcBu revealed an onset temperature of decomposition (2% mass loss) of approx. 290 °C. The novel PAHE-based FR was incorporated into a polypropylene-polyethylene copolymer (PP-co-PE) together with poly-tert-butylphenol disulfide (PBDS) (8 wt.%/2 wt.%) as a synergist. The PP-PE samples achieved V2 classification in the UL 94 V test. In addition, specimens of a rapeseed oil-based polyamide containing PAHE-functionalized CeAcBu at 20 wt.% loading yielded a V2 rating with short burning times. [ABSTRACT FROM AUTHOR]

Addition of the P−H bond in bis(mesitoyl)phosphine, HP(COMes)2 (BAPH), to a wide variety of activated carbon–carbon double bonds as acceptors was investigated. While this phospha‐Michael addition does not proceed in the absence of an additive or catalyst, excellent results were obtained with stoichiometric basic potassium or caesium salts. Simple amine bases can be employed in catalytic amounts, and tetramethylguanidine (TMG) in particular is an outstanding catalyst that allows the preparation of bis(acyl)phosphines, R−P(COMes)2, under very mild conditions in excellent yields after only a short time. All phosphines RP(COMes)2 can subsequently be oxidized to the corresponding bis(acyl)phosphane oxides, RPO(COMes)2, a substance class belonging to the most potent photoinitiators for radical polymerizations known to date. Thus, a simple and highly atom economic method has been found that allows the preparation of a broad range of photoinitiators adapted to their specific field of application even on a large scale. [ABSTRACT FROM AUTHOR]

Microwave-assisted phospha-Michael addition reactions were carried out in the 13α-oestrone series. The exocyclic 16-methylene-17-ketones as α,β-unsaturated ketones were reacted with secondary phosphine oxides as nucleophilic partners. The addition reactions furnished the two tertiary phosphine oxide diastereomers in high yields. The main product was the 16α-isomer. The antiproliferative activities of the newly synthesised organophosphorus compounds against a panel of nine human cancer cell lines were investigated by means of MTT assays. The most potent compound, the diphenylphosphine oxide derivative in the 3-O-methyl-13α-oestrone series (9), exerted selective cell growth-inhibitory activity against UPCI-SCC-131 and T47D cell lines with low micromolar IC50 values. Moreover, it displayed good tumour selectivity property determined against non-cancerous mouse fibroblast cells.

Alkaline hydrolysis of a variety of (4-(2-alkenoyl)phenyl)triarylphosphonium bromides is reported. This hydrolysis triggers coupling of 4-(2-alkenoyl)phenyl with one aryl via phosphorus(V). Both diarylphosphinite and an α,β-unsaturated ketone are in situ generated and then undergo phospha-Michael addition to provide β-diarylphosphoryl ketones bearing a biaryl moiety in 27–70% yields in the absence of a transition metal. [ABSTRACT FROM AUTHOR]

Microwave-assisted phospha-Michael addition reactions were carried out in the 13α-oestrone series. The exocyclic 16-methylene-17-ketones as α,β-unsaturated ketones were reacted with secondary phosphine oxides as nucleophilic partners. The addition reactions furnished the two tertiary phosphine oxide diastereomers in high yields. The main product was the 16α-isomer. The antiproliferative activities of the newly synthesised organophosphorus compounds against a panel of nine human cancer cell lines were investigated by means of MTT assays. The most potent compound, the diphenylphosphine oxide derivative in the 3-O-methyl-13α-oestrone series (9), exerted selective cell growth-inhibitory activity against UPCI-SCC-131 and T47D cell lines with low micromolar IC50 values. Moreover, it displayed good tumour selectivity property determined against non-cancerous mouse fibroblast cells. [ABSTRACT FROM AUTHOR]

We report an efficient method for the direct β-acylation of 2-ylideneoxindoles with acyl chlorides that is catalyzed by organophosphanes in the presence of base. A variety of functionalized 2-ylideneoxindoles were prepared in moderate to good yields under mild, metal-free conditions via a tandem phospha-Michael/O-acylation/intramolecular cyclization/rearrangement sequence. Mechanistic investigations revealed that C–O bond cleavage on a possible betaine intermediate is the key step for the installation of the keto-functionality at the β-position of 2-ylideneoxindoles in a highly stereospecific manner. The synthetic utility of this protocol could also be proven by a scale-up reaction and synthetic transformations of the products. [ABSTRACT FROM AUTHOR]

A relay Cu(I)/Brønsted base catalyzed one‐pot phospha‐Michael addition/5‐exo‐dig cyclization/isomerization of in situ generated aza‐alkynyl o‐quinone methides (N‐o‐AQMs) from 1‐(o‐aminophenyl)prop‐2‐ynols with P(O)‐compounds has been established to afford C3‐phosphorylated indoles. It demonstrates that the 1,4‐conjugate addition adduct from N‐o‐AQMs could undergo further cyclization with the tethered alkyne moiety to afford N‐heterocyclic compounds. [ABSTRACT FROM AUTHOR]

By nucleophilic addition of phosphite P(OMe)3 to a cage‐opened C60 derivative, α‐hydrophosphate and enol phosphate were obtained as kinetic and thermodynamic products, respectively. Different from classical Abramov products bearing a phosphorus–carbon bond, these products have a phosphorus–oxygen bond. The observed anomaly originates from the fully conjugated π system, which significantly stabilizes zwitterionic intermediates bearing a phosphorus–oxygen bond. The thus formed enol phosphate was found to exhibit an intense absorption band that extended to 730 nm, reflecting the intramolecular charge‐transfer transitions. We also report domino phosphorylation reactions, which gave a cage‐opened C60 derivative bearing a direct P−C bond. [ABSTRACT FROM AUTHOR]

Conjugate addition of the long chain dialkyl phosphites to electron-deficient alkenes under PBu3 catalysis afforded the corresponding phosphonates in good yields in a short reaction time. Long chain alkyl groups in the phosphites were well tolerated in this transformation. The products of this reaction are of particular interest as components of lubrication oil composition. [ABSTRACT FROM AUTHOR]

A tandem phospha‐Michael addition/N‐acylation/intramolecular Wittig reaction of in situ formed aza‐o‐QMs is disclosed. This approach features high functional group tolerance and provides a convenient and practical access to biologically significant indole derivatives (37 examples, up to 91% yield) under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Abstract Organophosphorus compounds provide great potential as replacements for traditional organohalogen flame retardants. Compounds containing the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) unit may be especially important. 2-Dopyl-1,4-di(2-dopylpropanoy)benzene contains three dopyl units (>10% P) all bound through carbon. It displays excellent flame retardancy in DGEBA epoxy resin. [ABSTRACT FROM AUTHOR]

Abstract A series of phosphonate-containing compounds based on dibenzo[ d,f ][1,3,2]dioxaphosphepine 6-oxide (BPPO) is presented. BPPO is synthesized by a three–component condensation and is added to activated alkenes with systematically varied structure via phospha-Michael addition. Acrylates, α,β-unsaturated carboxylic acid diesters and benzoquinone are used as activated alkenes. The new compounds are characterized by 1H, 13C and 31P NMR spectroscopy. The as-prepared phosphonates are envisioned to have flame retardant properties. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

A series of biobased phosphorus flame retardants has been prepared by converting starch-derived bis-2,5-(hydroxymethyl)furan to the corresponding diacrylate followed by Michael addition of phosphite to generate derivatives with phosphorus moieties attached via P−C bonds. All compounds behave as effective flame retardants in DGEBA epoxy resin. The most effective is the DOPO derivative, 2,5-di[(3-dopyl-propanoyl)methyl]furan. When incorporated into a DGEBA blend at a level to provide 2% phosphorus, a material displaying a LOI of 30, an UL 94 rating of V0 and a 40% reduction in combustion peak heat release rate compared to that for resin containing no additive is obtained. The analogous compounds generated from bisphenol A and tetrabromobisphenol A exhibit similar flame-retarding properties.

In this account, our group's efforts towards exploring new substrates as precursors for the Wittig reaction have been discussed. Several new strategies developed by our group for the generation of requisite ylides for the Wittig reaction are highlighted. The idea behind the development of some chemoselective and diversity-oriented strategies are discussed in detail in a progressive manner. These strategies encompass a wide range of substrates that are employed for the synthesis of an array of heterocycles and multifunctional olefins and present a huge scope for their application on an industrial level. [ABSTRACT FROM AUTHOR]

New antineoplastic series of substituted benzothiazolo-β-aminobisphosphonic acids have been developed on the basis of the prospecting potency of the benzothiazole motifs and the aminomethylenebisphosphonate moiety as well as on the prediction of the biological activity utilizing computer program PASS, version 2014-1. Target compounds were obtained in excellent yields (70-90%) via Phospha-Michael-type addition reaction of tetraethyl methylene-1,1-bisphosphonate reagent to a group of Schiff bases incorporating benzothiazole moiety. The reactions proceeded under microwave irradiation, utilizing the advantages of the environment, friendly protocol such as high efficiency, short reaction time, and excellent yields. In consistency with the prospected results, the new NBP acids revealed positive properties against human breast and colon tumor cell lines. Remarkable potency for six lead compounds (out of 12) was observed against breast (MCF7, MDAMB/435, MDAMB/231/ATCC, HS-578T with GI50: 2.05-6.47 μM) and colon (COLO-205, HCT-116, HCC-2998, and SW-620 with GI50: 3.03-7.92 μM) carcinoma cell lines when compared with the positive control Adriamycin (breast, GI50: 3.27-6.64 μM; colon, GI50: 4.09-8.75 μM). Notably, there is a consistency between the prediction and the determined biological results. [ABSTRACT FROM AUTHOR]

The PBu 3 -catalyzed conjugate addition of diphenylphosphine oxide to unsubstituted and substituted electron-deficient alkenes is reported. β-Substituted α,β-unsaturated esters, trans -methyl crotonate and trans -methyl cinnamate, known for their reluctance to participate in phosphine-catalyzed transformations, also react well under the developed conditions. Mild reaction conditions, simple work-up and the ease of catalyst recovery make the proposed methodology useful for the preparation of functionalized tertiary phosphine oxides. The utility of this method was demonstrated by the gram-scale reactions of diphenylphosphine oxide with electron-deficient alkenes. [ABSTRACT FROM AUTHOR]

A simple, clean, and efficient approach for the one-pot synthesis of 2-oxindol-3-ylphosphonates has been successfully developed. With 7 mol% loading of the 1,4-diazabicyclo[2.2.2]octane-based ionic liquid catalyst, 2-oxindol-3-ylphosphonates form in good to excellent yields within short times. This tandem reaction involves a phospha- Michael addition to the activated alkenes, which form in situ by Knoevenagel condensation. The corresponding products are easily separated and purified by simple crystallization. The catalyst can be recycled five times without significant activity loss. This approach is readily amenable to large-scale synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] The phospha-Michael addition (PMA) to many Michael acceptors like nitro-olefins, cyclic enones is well known. Chalcones and α,β-unsaturated esters are rarely employed in PMA reaction. In this article, we report the PMA of biphenylphosphine oxide to chalcone and α , β -unsaturated esters using the newly identified organocatalyst 1,1-diaminobenzalazine. The reaction has wide substrate scope, and the products were formed with very good yields. This work establishes the versatility of the organocatalyst 1,1-diaminobenzalazine in producing substituted 3-(diphenylphosphoryl)-1,3-diphenylpropan-1-ones. [ABSTRACT FROM AUTHOR]

A convenient and mild procedure is developed forβ-nitrophosphonates via phospha-Michael addition of phosphites to nitrostyrene at room temperature in the presence of 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU)–based ionic liquid [DBUH][OAc]. The operational simplicity, convenient workup, and reusability of the ionic liquid make this method attractive. [ABSTRACT FROM PUBLISHER]

Polystyrene-supported DABCO was employed for the first time as a recyclable heterogeneous basic catalyst for one-pot synthesis of β-phosphonomalonates via tandem Knoevenagel–phospha-Michael reaction at room temperature. The reaction conditions are mild and the method is operationally simple. The catalyst could be easily separated from the reaction mixture by filtration and recycled six times without activity loss. [ABSTRACT FROM AUTHOR]

Knoevenagel condensation reaction of an aldehyde and Meldrum's acid produces a 5-arylmethylidene Meldrum's acid, which undergoes Michael addition of a trialkyl phosphite under solvent- free conditions to afford the title compounds in good yields. [ABSTRACT FROM AUTHOR]

A novel phosphorus-containing vegetable oil (PETR) was prepared through phospha-Michael addition of a diphenyl phosphine oxide to the enone derivative of high-oleic sunflower oil (ETR). The reaction was investigated using the enone derivative of methyl oleate under conventional thermal heating and microwave irradiation. The kinetic study showed a great enhancement of reaction rate for the microwave-initiated addition. The crosslinking of ETR with diaminodiphenylmethane (DDM) via aza-Michael addition was also investigated under microwave irradiation, showing a noticeable acceleration of the curing. The new phosphorus-containing triglyceride was crosslinked with DDM to obtain phosphorus-containing vegetable oil-based thermosets of different phosphorus contents. Limiting oxygen index values from 26.4 to 35.0 for the final materials were obtained, demonstrating that the flame retardant properties of vegetable oil-based thermosets can be improved by adding covalently bonded phosphorus to the polymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

Abstract: 3-Aminopropylated silica gel, which is prepared from commercially available and cheap starting materials, is introduced as an efficient and recyclable catalyst for the phospha-Michael addition of phosphorus nucleophiles to α,β-unsaturated malonates. Short reaction times, mild reaction conditions, ease of recovery and catalyst reusability make this method a new, economic and waste-free chemical process for the synthesis of β-phosphonomalonates. [ABSTRACT FROM AUTHOR]

An efficient synthesis of β-phosphono malonates via phospha-Michael addition of phosphorous nucleophiles to α,β-unsaturated malonates in the presence of HClO4-SiO2 as a new and �recyclable catalyst is described. [ABSTRACT FROM AUTHOR]

Abstract: The reaction of 1,2-diaza-1,3-butadienes with dialkyl phenylphosphonites under solvent-free conditions proceeds via zwitterionic intermediate and gives, by precipitation, the stable ylidic α-phosphanylidene-hydrazones that, in turn, can be transformed into the corresponding 3-phenyl-2H-1,2,3λ5-diazaphospholes. The latter compounds are converted by hydrolytic cleavage in methanol–water (95:5) into E-hydrazonophosphonates that are useful for the preparation of the corresponding β-ketophosphonates and 4-[alkoxy(phenyl)phosphoryl]-1,2-diaza-1,3-butadienes. These peculiar 1,2-diaza-1,3-butadienes, bearing an alkoxy(phenyl)phosphoryl group on the carbon atom in position 4 are also able to add different nucleophiles, such as methanol or thiourea, giving 2-[alkoxy(phenyl)phosphoryl]-2-methoxyhydrazones and 5-phosphinate-substituted thiazol-4-ones, respectively. [Copyright &y& Elsevier]

Kabachnik-Fields reactions of a variety of amines, phospha-Michael additions to maleimide derivatives and alcoholysis of dialkyl phosphites were studied under microwave conditions. [ABSTRACT FROM PUBLISHER]

A series of biobased phosphorus flame retardants has been prepared by converting starch-derived bis-2,5-(hydroxymethyl)furan to the corresponding diacrylate followed by Michael addition of phosphite to generate derivatives with phosphorus moieties attached via P–C bonds. All compounds behave as effective flame retardants in DGEBA epoxy resin. The most effective is the DOPO derivative, 2,5-di[(3-dopyl-propanoyl)methyl]furan. When incorporated into a DGEBA blend at a level to provide 2% phosphorus, a material displaying a LOI of 30, an UL 94 rating of V0 and a 40% reduction in combustion peak heat release rate compared to that for resin containing no additive is obtained. The analogous compounds generated from bisphenol A and tetrabromobisphenol A exhibit similar flame-retarding properties. [ABSTRACT FROM AUTHOR]

By nucleophilic addition of phosphite P(OMe) 3 to a cage-opened C 60 derivative, α-hydrophosphate and enol phosphate were obtained as kinetic and thermodynamic products, respectively. Different from classical Abramov products bearing a phosphorus-carbon bond, these products have a phosphorus-oxygen bond. The observed anomaly originates from the fully conjugated π system, which significantly stabilizes zwitterionic intermediates bearing a phosphorus-oxygen bond. The thus formed enol phosphate was found to exhibit an intense absorption band that extended to 730 nm, reflecting the intramolecular charge-transfer transitions. We also report domino phosphorylation reactions, which gave a cage-opened C 60 derivative bearing a direct P-C bond., (© 2020 Wiley-VCH GmbH.)

A series of new flame retardants (FR) based on dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO) incorporating acrylates and benzoquinone were developed previously. In this study, we examine the fire behavior of the new flame retardants in polyisocyanurate (PIR) foams. The foam characteristics, thermal decomposition, and fire behavior are investigated. The fire properties of the foams containing BPPO-based derivatives were found to depend on the chemical structure of the substituents. We also compare our results to state-of-the-art non-halogenated FR such as triphenylphosphate and chemically similar phosphinate, i.e. 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO), based derivatives to discuss the role of the phosphorus oxidation state. [ABSTRACT FROM AUTHOR]

A new type of click reaction between an alkyl phosphine and acrylamide was developed and applied for site-specific protein labeling in vitro and in live cells. Acrylamide is a small electrophilic olefin that readily undergoes phospha-Michael addition with an alkyl phosphine. Our kinetic study indicated a second-order rate constant of 0.07 m(-1)  s(-1) for the reaction between tris(2-carboxyethyl)phosphine and acrylamide at pH 7.4. To demonstrate its application in protein functionalization, we used a dansyl-phosphine conjugate to successfully label proteins that were site-specifically installed with N(ɛ) -acryloyl-l-lysine and employed a biotin-phosphine conjugate to selectively probe human proteins that were metabolically labeled with N-acryloyl-galactosamine., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)