phospha-Michael Addition Research Articles

Palladacycle catalyzed asymmetric P-H addition of diarylphosphines to N-enoyl phthalimides.

The first asymmetric phospha-Michael addition of diarylphosphines to N-enoyl phthalimides has been developed in the presence of a chiral palladacycle catalyst. A library of free chiral tertiary phosphine adducts were directly obtained with excellent yields and enantioselectivities. Products can be subsequently functionalized to afford β-phosphinoamides, the direct preparation of which from cinnamides has been notoriously challenging.

Novel Ionic Tagged Amine Anchored on Magnetic Nanoparticles: An Efficient and Magnetically Recyclable Catalyst for Phospha-Michael Addition

Ionic tagged propyl amine immobilized on magnetic nanoparticles (MNPs) was synthesized and fully characterized. The novel catalyst (MNPs@PA-IL) was applied in phospha-Michael addition and gave the desired β-phosphonomalonates in good yields. The MNPs supported catalyst with ionic tag could be readily recovered from the reaction mixture using an external magnet. Compared with ionic-free counterpart (MNPs@PA), MNPs@PA-IL present better catalytic activity. The proposed mechanism regarding the MNPs@PA-IL catalyzed phospha-Michael reaction was also discussed.

ChemInform Abstract: N‐Heterocyclic Carbene Catalyzed Carba‐, Sulfa‐, and Phospha‐Michael Additions with NHC·CO2 Adducts as Precatalysts.

N-heterocyclic carbene catalyzed Michael additions have been revisited with 1,3-dialkyl- or 1,3-diarylimidazol(in)ium-2-carboxylates, that is, NHC·CO2 adducts, as the source of the free NHC catalysts in solution. Using these precatalysts, a number of efficient carba-, sulfa-, and phospha-Michael additions were achieved very conveniently, without the need for an external strong base to generate the NHC by deprotonation of an azolium salt. To further expand the scope of the procedure, some NHC-catalyzed sulfa-Michael/aldol organocascades were also investigated.

Microwave-Assisted Synthesis of P-Heterocycles*

The direct esterification, thioesterification and amidation of cyclic phosphinic acids, such as 1-hydroxy-3-phospholene 1-oxides, 1-hydroxy-phospholane 1-oxides and a 1-hydroxy-1,2,3,4,5,6-hexahydrophosphinine 1-oxide, which do not take place on conventional heating, were carried out under MW conditions in excess of the alcohol, thioalcohol and amine, respectively. The cyclic phosphinates were also prepared by MW-assisted alkylating esterification of the corresponding phosphinic acids in solid–liquid phase. Using alkyl halides of normal reactivity, the application of a phase transfer catalyst was also beneficial. In addition, MW-assisted Diels–Alder reactions, so-called inverse Wittig-type reactions furnishing β-oxophosphoranes, a few kinds of phospha-Michael additions leading to precursors of bidentate P-ligands, and a few Kabachnik–Fields condensations affording α-aminophosphonates and α-aminophosphine oxides are discussed.

Chiral ytterbium silylamide catalyzed enantioselective phospha-Michael addition of diethyl phosphite to chalcones

An efficient and enantioselective phospha-Michael addition of diethyl phosphite to chalcones has been established. In the presence of a catalytic amount of chiral lanthanide silylamide generated from [(Me3Si)2N]3Yb(μ-Cl)Li(THF)3 and salen, the reaction produced the target γ-oxophosphonates with high yields and enantioselectivity.

Phospha-Michael Addition to In Situ Prepared 5-Arylmethylidene Meldrum’s Acids

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.

N-Heterocyclic Carbene Catalyzed Carba-, Sulfa-, and Phospha-Michael Additions with NHC·CO2 Adducts as Precatalysts

N-heterocyclic carbene catalyzed Michael additions have been revisited with 1,3-dialkyl- or 1,3-diarylimidazol(in)ium-2-carboxylates, that is, NHC·CO2 adducts, as the source of the free NHC catalysts in solution. Using these precatalysts, a number of efficient carba-, sulfa-, and phospha-Michael additions were achieved very conveniently, without the need for an external strong base to generate the NHC by deprotonation of an azolium salt. To further expand the scope of the procedure, some NHC-catalyzed sulfa-Michael/aldol organocascades were also investigated.

Enantioselective phospha-Michael addition of diarylphosphines to β,γ-unsaturated α-ketoesters and amides

An enantioselective hydrophosphination of β,γ-unsaturated α-ketoesters and amides has been developed using a chiral palladacycle catalyst. Adducts can be obtained in excellent yields and enantioselectivities, providing direct access to chiral tertiary phosphines which are synthetically useful intermediates in the preparation of bidentate ligands.

ChemInform Abstract: Microwave‐Assisted Organophosphorus Synthesis

The spread of microwave (MW) equipment has brought about a tremendous development in synthetic organic chemistry. This environmentally friendly methodology, associated often with solventless conditions, has also had a positive impact on organophosphorus chemistry, allowing new reactions to be carried out, or increasing the rate, selectivity and yield. In special cases, MW irradiation may replace phase transfer or other kinds of catalysts. Reactions, such as the derivatization of phosphinic acids, the inverse Wittig protocol, Diels– Alder cycloadditions, fragmentation-related phosphorylations, phospha-Michael additions, Kabachnik–Fields condensations, the addition of >P(O)H species to carbonyl compounds, substitution of

Microwave-Assisted Organophosphorus Synthesis

The spread of microwave (MW) equipment has brought about a tremendous development in synthetic organic chemistry. This environmentally friendly methodology, associated often with solventless conditions, has also had a positive impact on organophosphorus chemistry, allowing new reactions to be carried out, or increasing the rate, selectivity and yield. In special cases, MW irradiation may replace phase transfer or other kinds of catalysts. Reactions, such as the derivatization of phosphinic acids, the inverse Wittig protocol, Diels– Alder cycloadditions, fragmentation-related phosphorylations, phospha-Michael additions, Kabachnik–Fields condensations, the addition of >P(O)H species to carbonyl compounds, substitution of

Phospha-Michael addition of diethyl phosphite to α,β-unsaturated malonates catalyzed by nano γ-Fe2O3-pyridine based catalyst as a new magnetically recyclable heterogeneous organic base

Nano γ-Fe2O3-pyridine based catalyst as a new magnetically recyclable heterogeneous organic base was synthesized. The synthesized odorless pyridine based catalyst was used as a new catalyst for the efficient synthesis of β-phosphonomalonates by the reaction of diethyl phosphite with α,β-unsaturated malonates. The catalyst was easily isolated from the reaction mixture by a magnetic bar and reused at least 10 times without significant degradation in the activity.

Microwave-Assisted Synthesis of Organophosphorus Compounds

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

Phospha-Michael addition to enone-containing triglyceride derivatives as an efficient route to flame retardant renewable thermosets

Phospha-Michael addition to enone-containing triglyceride derivatives as an efficient route to flame retardant renewable thermosets

Phospha-Michael addition to enone-containing triglyceride derivatives as an efficient route to flame retardant renewable thermosets

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

Phospha-Michael Additions to Activated Internal Alkenes: Steric and Electronic Effects

The addition of P(O)-H bonds to internal alkenes has been accomplished under solvent-free conditions without the addition of a catalyst or radical initiator. Using a prototypical secondary phosphine oxide, a range of substrates including cinnamates, crotonates, coumarins, sulfones, and chalcones were successfully functionalized. Highly activated acceptors such as isopropylidenemalononitrile and ethyl 2-cyano-3-methyl-2-butenoate underwent the phospha-Michael reaction upon simple trituration of the reagents at room temperature, whereas less activated substrates such as ethyl cinnamate and methyl crotonate required heating (>150 °C) in a microwave reactor to achieve significant consumption of the starting alkenes. For the latter alkenes, a competing reaction involving disproportionation of the ditolylphosphine oxide into ditolylphosphinic acid and ditolylphosphine was observed at the high temperatures needed to promote the addition reaction.

ChemInform Abstract: Phospha‐Michael Addition of Phosphorus Nucleophiles to α,β‐Unsaturated Malonates Using 3‐Aminopropylated Silica Gel as an Efficient and Recyclable Catalyst.

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.

The Phospha–Michael addition product {(t-BuNH)P(μ-N-t-Bu)2P(=N-t-Bu)—C(=CH2)CH(p-CH3O—C6H4)-P(O)[(OCH2C(CH3)2CH2O)

The title compound, 2-{2-[1,3-di-tert-butyl-4-(tert-butyl­amino)-2-(tert-butyl­imino)-1,3,2λ5,4-diaza­diphosphetidin-2-yl]-1-(4-meth­oxy­phen­yl)prop-2-en-1-yl}-5,5-dimethyl-1,3,2λ5-dioxaphosphinan-2-one, C31H57N4O4P3, was synthesized from the Phospha–Michael addition reaction of cyclo­diphos­pha­zane [(t-BuNH)P(μ-Nt-Bu)]2 and allenyl­phospho­nate [(OCH2C(CH3)2CH2O)P(O)C(p-CH3O—C6H4)=C=CH2]. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules. The structure exhibits pseudosymmetry but attempts to solve it in a higher (monoclinic) space group were unsuccessful.

Phosphomolybdic acid: An efficient and reusable catalyst for the synthesis of β-phosphono malonates

Phosphomolybdic acid (H3PMo12O40) is an efficient and reusable catalyst for the synthesis of the phospha-Michael addition of phosphite esters with different types of α,β-unsaturated malonates to produce a variety of β-phosphono malonates.

Phospha-Michael addition of phosphorus nucleophiles to α,β-unsaturated malonates using 3-aminopropylated silica gel as an efficient and recyclable catalyst

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.

HClO4-SiO2 as a Novel and Recyclable Catalyst for the Phospha-Michael Addition of Phosphorous Nucleophiles to α,β-Unsaturated Malonates

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.