Reactions of β-Ketophosphonates and Enamine Phosphonates with Electrophilic Reagents

Abstract

The direction of the reactions of β-ketophosphonates and enamine phosphonates strongly depends on the structure of substrates and electrophiles. Regio- and stereoselectivity on the reaction of anionic P-ketophosphonates depends on the nature of cation and solvent. The yield of O-products increases substantially when going from alkylation to acylation, and in particular to phosphorylation.     

Synthetic Utilization of α-Phosphonovinyl Anions

The α-phosphonovinyl anions, generated in situ from treatment of β-hetero-substituted vinyl-phosphonates 1a-c with LDA (or LTMP), were trapped with various electrophiles such as chlorotriorganosilanes, chlorotrimethylgermane, chlorotriorganotins, dimethyl disulfide, and halogen to afford the corresponding β-hetero-substituted α-functionalized vinylphosphonates 2–14 in good to excellent yields. The Friedel-Crafts reaction of α-(silyl) or α-(germyl)phosphonoketene dithioacetals 2, 9 or 4 with acid chlorides gave α-acylated phosphonoketene dithioacetals 15–19 in 53–91 % yields. The palladium-catalyzed cross-coupling reaction of β-ethoxy-α-(tributylstannyl)vinylphosphonate 13 with a variety of organic halides (R = acyl, allyl, aryl etc.) provided β-ethoxy-α-substituted vinylphosphonates 20–25 in good to moderate yields. The palladium-mediated cross-coupling reaction of α-(iodo)-vinyl-phosphonates 7, 14 with terminal acetylenes afforded α-alkynylated vinylphosphonates 26–29 in 69–83 % yields.     

Synthesis of N-(alkoxycarbonyl or alkoxycarbonyl-methyl-alkoxyphosphonyl)-α-amino-O, O-diphenyl phosphonates and their bioactivities

With phosphonoformic acid (PFA) and its analog, phosphonoacetic acid (PAA), as the lead compounds, α-amino phosphonates were introduced into PFA and PAA. The derivatives of N-(alkoxycarbonyl-alkoxyphosphonyl)-α-amino phosphonates (I) and N-(alkoxycarbonyl-methyl-alkoxyphosphonyl)-α-amino phosphonates (II) with the N-terminal of amino phosphonates bonding to phosphorus atom of PFA andPAA were synthesized via the reaction of the corresponding phosphonyl chloride with α-amino phosphonates in the presence of a base. The³¹P NMR spectra of I and II were determined. It is found that the coupling constants³ J _pp with R³ being alkyl group were lower than those with R³ being (substituted) phenyl, and this result was discussed. The preliminary bioassay showed that some of the compounds I and II have better activities against tobacco mosaic virus (TMV). The inhibitory was higher than that of DHT (2, 4-dioxyhexahydro-1, 3, 5-triazine). In addition, some of the compounds showed the activity against cancer cells. Project supported by the National Natural Science Foundation of China.     

Reactions of vinylphosphonates with piperazines

Russian Journal of General Chemistry - Dialkyl [2-(piperazin-1-yl)ethyl]phosphonates were obtained by the reactions of piperazine with dialkyl vinylphosphonates. The addition of...     

Radical Addition of Bis(Trimethylsilyl)Phosphonate to Vinyltrimethylsilane: Crystal Structure of (2-Trimethylsilylethyl)Phosphonic Acid

Abstract

The formation of phosphorus-carbon bond by free radical addition of phosphorus compounds containing P-H bond to olefins has been known since more than three decades ago. Alkyl or aryl phosphins, phosphinates, phosphonates and phosphorus or hypophosphorus acid have been used in these reactions, but a little attention have been paid to silyl phosphonates. As a part of ongoing study on the structure and reactivity of organosilicon-phosphonate compounds, we synthesized bis(trimethylsi1yl) (2-trimethylsilylethyl)phosphonate (I) by the reaction of bis(trimethylsily1) phosphonate with vinyltrimethylsilane in the presence of a peroxide. The product was characterized by its ¹H and ³¹P NMR and IR spectra. Hydrolysis of (I) led to the formation of corresponding phosphonic acid (n). The crystal structure of (11) has been determined by X-ray diffraction analysis.     

Fluoroalkyl alpha,beta-unsaturated imines. Valuable synthetic intermediates from primary fluorinated enamine phosphonates

[reaction: see text] A simple method for the preparation of fluoroalkyl allylamines or alpha,beta-unsaturated ketones by an olefination reaction of primary enamine phosphonates and aldehydes, followed by selective reduction with hydrides or hydrolysis, is reported. Fluorinated beta-amino nitriles are also obtained by an olefination reaction of primary enamine phosphonates with aldehydes and subsequent addition of metalated acetonitrile.     

STUDIES ON CYCLOADDITION REACTIONS OF VINYLPHOSPHONATES WITH NITRONES

Cycloaddition reactions of vinylphosphonates with nitrones were studied. A series of 4-phosphonyl-3-aryl-N-arylisoxazolidines were synthesized by the reaction of vinylphosphonates with nitrones. The structure of 3a was confirmed by X-ray single-crystal diffraction.     

Novel 4-chloro-or-4-bromoresorcinol-based bicyclic phosphonates

Abstract

The reaction of 4-chloro- and 4-bromoresorcinol with 2-ethoxyvinylphosphonic acid dichloroanhydride has been investigated for the first time. It has been determined that the product of the reaction is the mixture of structural isomers of bicyclic phosphonates at the ratio of 9:1. The structure and composition of the compounds have been elucidated from ¹H, ³¹P, and ¹³C NMR spectroscopy, mass-spectrometry (MALDI-TOF), as well as elemental and X-ray analysis.     

N-(R-Cyclopropyl) Trifluoroacetimidoyl Phosphonates

Abstract

A convenient synthetic approach for previously unknown N-(R-cyclopropyl)trifluoroacetimidoyl phosphonates 5a,b (R?H, CF₃) was developed on the basis of the reaction of respective trifluoroacetimidoyl chlorides with triethyl phosphite. It was shown that imidoyl phosphonates 5a,b exist as equilibrium mixture of Z/E isomers (Z:E ～92:8). Activation parameters of Z–E isomerization were evaluated by ¹⁹F NMR spectroscopy. Catalytic hydrogenation of 5a,b can serve as a convenient method for the synthesis of trifluoroethylaminophosphonates with a rigid N-cyclopropyl group.     

Phosphorylation of Nitrogen-Bearing Unsaturated and Aromatic Compounds

Abstract

The enamine reaction provides a valuable method for the selective alkylation and acylation of aldehydes and keto-nes. Similar procedure of phosphorylation is not practically studied. Using 1,3,3-trimethyl-2-methyleneindoline (Fischer's base) as the model enamine we investigated conditions of phosphorylation as well as stereochemistry, and reactions of obtained products of type 1. It was found that properties of some compounds were similar to those of amides of phosphorus acids (vinilologie).     

(α-Phosphoryl Carbanions. Searching of Course of Wittig-Horner Reaction by 31P Low Temperature NMR

Abstract

Continuing our studies on utilization of the Wittig-Horner reaction in organic synthesis, we have examined reactivity of α-lithium derivatives of several phosphonates towards carbonyl compounds, by ³¹P NMR at low temperature (from -100°C to r.t.). The chemical shifts δ [ppm] of a few representative phosphonates (1), carbanions (2) and betains (3) will be given.     

A selective synthesis of enamines versus aziridines

The reaction of 10‐azidoacetyl‐10H‐phenothiazine with olefinic dipolarophiles depends on the reaction temperature. In refluxing toluene, a mixture of enamine and aziridine is formed in 3:1 ratio. The reaction mechanism appears to involve a Michael‐type addition of the nucleophilic N¹ azide atom to the olefinic double bond. In chloroform, a cycloaddition reaction takes place with the formation of a 4,5‐dihydro‐1,2,3‐triazole. The heating of dihydrotriazoles in toluene is accompanied by nitrogen elimination leading to a mixture of enamine and aziridine in 1:3 ratio. J. Heterocyclic Chem., 2011.     

Synthesis of New Phosphonate Derivatives of Naphtho[2,1-b[Pyran]3,2-e][1,2,4]Triazolo [1,5-c]Pyrimidines

Abstract

The synthesis of new naphthopyranotriazolopyrimidines phosphonates 4a–i in good yields (74%–93%) has been accomplished via Michaelis–Arbusov rearrangement by the reaction of trialkyl phosphite with naphthopyranotriazolopyrimidines chloride 3a–e, which were obtained from α-functionalized iminoethers 1 in two steps. The synthesized compounds 4a–i were completely characterized by IR, ¹H, ¹³C, and ³¹P NMR and HRMS.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis of new α-hydroxyphosphonates and α-acetoxyphosphonates

A series of new α-hydroxyphosphonate (5–14) have been synthesized in high yields by reaction of β-chloro-α,β-unsaturated aldehydes (1–4) and trialkyl phosphite in the presence of chlorotrimethylsilane at room temperature under solvent-free conditions. In addition, compounds (5–14) were reacted with acetic anhydride in DBU to give the new α-acetoxyphosphonate derivatives (15–23). All these phosphonates (5–23) were obtained as mixtures of two (E and Z) isomers and fully characterized by multinuclear (¹H, ¹³C, and ³¹P) NMR, IR spectroscopy and HRMS.     

HIGH YIELD SYNTHESIS OF α-ALKOXYPHOSPHONIUM SALTS AND α-ALKOXYPHOSPHONATES

Abstract

The recent work of Ley et al. ¹ on α-alkoxyphosphorane compounds from cyclic enolethers has prompted us to report our findings in this area. In addition to cyclic enol ethers we have studied the acyclic case as well as the use of phosphite in place of triphenylphosphine. Using this approach we have prepared alkoxy-as well as 5-and 6-membered oxyheterocyclic phosphonium salts and phosphonates in high yield.     

Oxidative Phosphonylation of Aromatic Compounds

Abstract

Aryl phosphonates can be prepared in good yields from the respective arenes and tri- or dialkylphosphites by either chemical or electrochemical oxidation^1. The anodic oxidation proceeds either via phosphonium radical cations which then attack the arenes electrophilically or via arene radical cations which add the trialkyl-phosphite as nucleophile^1,2. Aryl phosphonates are also obtained in good yields by chemical oxidation with peroxidisulfate/AgNO₃, Iron(III)- or Cerium(IV)-complexes in acetonitrile/water or glacial acetic acid^3.     

New Synthetic Routes to β-Olefinic Trialkoxyphosphonium Salts and Phosphonates: Organometallic Variants of the Michaelis-Arbuzov Reaction

The low-temperature addition of tertiary phosphites to [(allyl)Fe (CO)₄]⁺X^? complexes proceeds regio- and stereospecifically and produces metal-coordinated β-olefinic trialkoxyphosphonium ions. These can be converted by various routes into the uncomplexed phosphonium salts or phosphonates. Similar reactions of acyclic [(dienyl)Fe(CO)₃]⁺X^? compounds give metal-coordinated (2,4-dien-1-yl)trialkoxyphosphonium salts or dialkyl (2,4-dien-1-yl)phosphonates. The mechanisms and their relationship to the classical Michaelis-Arbuzov reaction are discussed. The new compounds are characterized, if possible, by ¹H-, ¹³C-, and ³¹P-NMR spectra. The new phosphonium salts and phosphonates, potentially useful for Wittig-Horner reactions, are difficult to obtain by conventional routes.     

三苯基锗炔基膦酸酯的合成和表征

０IntroductionInrecentyears，thechemistryoforganogermaniumcompoundswasextensivelystudiedbecauseoftheirbiologicalactivity犤１，２犦．Organotinderivativesofoxyandthiophosphorusacidarewell－known犤３～５犦．Inourearlywork，theorganotinderivativesofalkynyloralkenylphosphateweresynthesizedandtheirstructuresandbiologicalactivitieswerealsostudied犤６～８犦．Sofar，tri－organogermaniumderivativesofphosphonicacidhavenotbeenreported．Inthispaper，O－bis（triphenylgermanium）alkynylphosphatesandO－trip…     

Vinylphosphite-Vinylphosphonate Rearrangement in Acyclic and Cyclic Systems

Abstract

Acyclic vinylphosphites (1) with π-acceptors at the β-carbon atom of vinyloxylic system and some cyclic vinylphosphites, 4-methylen-1,3,2-dioxaphosphorines (2) with electron withdrawing groups at C⁵ in the heterocycle, and 4-methylen-1,3,2-oxazaphosphorines (3), may undergo earlier unknown vinylphosphite-vinylphosphonate rearrangement. This rearrangement seems formally like a migration of the phosphorus-containing fragment to a-carbon of vinyloxylic system and results in the formation of acyclic vinylphos-phonates (4) in the case of (I), 2-oxo-3-methylen-1,2-oxa-phospholenes (5) and 2-oxo-5-methylen-1,2-azaphospholenes (6) in the cases (2) and (3) respectively. Isomerization is favoured by electrondonating groups at the phosphorus (111) atom. It is likely that the rearrangement of (1) and (2) proceeds through the stage of formation of cyclic oxeten-cation and disubstituted phosphite-anion as intermediates, which then combine to vinylphosphonates.