Synthesis of New Stable Phosphorus Ylides and 1,4‐Diionic Organophosphorus Compound from a Reaction between Hexamethyl Phosphorous Triamide and Dimethyl Acetylenedicarboxylate in the Presence of CH‐Acids

A simple and efficient one‐pot three‐component reaction between hexamethyl phosphorous triamide and dimethyl acetylenedicarboxylate (DMAD) in the presence of CH‐acids, such as acetylacetone, 1,3‐indandione, dibenzoylmethane, anthrone, and N,N‐dimethylbarbituric acid, has been studied. In all cases, new and stable phosphorus ylides are obtained in excellent yields. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond, resulting from conjugation of the ylide moiety with the adjacent carbonyl group. From the reaction of N,N‐dimethylbarbituric acid with DMAD in the presence of hexamethyl phosphorous triamide, a 1,4‐diionic organophosphorus compound is obtained. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:84–89, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21067     

NMR study and AIM analysis for assignment of the two Z- and E-isomers in phosphorane containing a 2-thiazoline-2-thiol

Triphenylphosphine reacts with dialkyl acetylenedicarboxylates in the presence of a SH-heterocyclic compound such as 2-thiazoline-2-thiol to generate stable phosphorus ylides. These stable ylides exist in solution as a mixture of the two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. In the recent work, NMR study and the assignment of more stable Z- or E-isomers as the major form were investigated by using natural population analysis (NPA).     

An Efficient One-Pot Synthesis of 2,3-Dialkyl-1,1-Diethyl-1-(Acetylamino)-3-(1,1,1-Triphenylphosphanilidene)-1,1,2,3-Propanetetracarboxylates and Their Temperature-Dependent NMR Spectra

Abstract

Stable crystalline phosphorus ylides of 1,1-diethyl 2,3-dimethyl 1-(acetylamino)-3-(1,1,1-triphenylphosphanilidine)-1,1,2,3-propanetetracarboxylates were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of diethyl acetamidomalonate as a CH-acid. These stable ylides exist in solution as a mixture of two geometrical isomers (E and Z) as a result of restricted rotation around the carbon–carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group on the nuclear magnetic resonance (NMR) time scale at ambient temperature. The dynamic effects in the ylide moieties were investigated by ¹H NMR spectra.

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.     

A Facile,One-Pot Synthesis of Azoic Compounds and Anthraquinone Derivatives Containing Dialkyl Phosphoryl Moieties in Multicomponent Reactions

Protonation of the reactive 1:1 intermediates produced in the reactions between triphenylphosphine and dialkyl acetylenedicarboxylates by 1-amino-anthraquinone or 1,5-diphenylcarbazone as a core dye leads to vinyl phosphonium salts, which undergo Michael addition with conjugate base of NH compounds to produce stable phosphorus ylides as novel dyes in fairly good yields. These ylides can exist in two geometrical isomers (Z) and (E) for 3, because the negative charge of the ylide moiety of these compounds are strongly conjugated with the adjacent carbonyl group. Rotation around the carbon–carbon double bond is slow in the (Z) and (E) geometrical isomers on the NMR time scale at ambient temperature. These compounds are assigned by their IR, ¹H, ¹³C NMR spectral data as well as their mass spectroscopic data.     

A Simple Synthesis of Stable Phosphorus Ylides from Indole and Some of Its Derivatives

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH acids, such as indole and 2-methyl indole, 3-methyl indole, and 5-boromo indole. These stable ylides exist in a solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

A Simple Synthesis of Stable Phosphoranes Derived from Imidazole Derivatives

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of strong NH-acids, such as imidazole, 2-methylimidazole, 4-methylimidazole, 2-ethylimidazole, benzimidazole, and 5,6-dimethylbezimidazole. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

Simple Synthesis of Stable Phosphorus Ylides Derived from Imidazolidine-2-Thione. Efficient One-Pot Synthesis of α-Amino Esters with β-Phosphorus Substituents

Crystalline phosphorus ylides are obtained in nearly quantitative yields from the addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and imidazolidine-2-thione. A dynamic NMR effect is observed in the ¹ H NMR spectrum of the stabilized ylide obtained from dimethyl acetylenedicarboxylate (Δ G ^≠ = 66.6 kJmol^?1 ) and is attributed to restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

An Efficient Synthesis of Stable Phosphorus Ylides Derived from Triphenylphosphine,Dialkyl Acetylenedicarboxylates,and an NH-Acid

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH-acids, such as benzotriazole, 5-methylbenzotriazole, 5-chlorobenzotriazole, pyrrole, 2-acetylpyrrole, pyrrole-2-carboxaldehyde, 4-nitro-acetanilide, 4-methoxyacetanilide, 4-bromoacetanilide, 4-methylacetanilide, 2-methyl-acetanilide, and 2,6-dimethylacetanilide. These stable ylides exist in a solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

Synthesis,Characterization, and Conformational Study of Acylhydrazones of α,β‐Unsaturated Aldehydes

New acylhydrazone derivatives 1–6 have been synthesized by condensation of tert‐butylphenoxyhydrazide and cinnamaldehyde A or β‐chloro‐α,β‐unsaturated aldehydes B–F . They were characterized by IR, (¹H, ¹³C, ¹⁹F) nuclear magnetic resonance (NMR), and high‐resolution mass spectroscopy. The NMR data show the existence of the cis/trans‐amide conformers due to N–C(O) bond rotation in addition to the E/Z isomers around the C=C bond of some of the starting aldehydes. The solvent polarity effects on the ratios of the cis/trans‐amide rotamers have also been investigated. Importantly, rotational barriers around the N–C(O) bond for all compounds 1–6 (62.9–68.8 kJ mol^–1) were calculated using the coalescence‐temperature method according to the Eyring equation. The results are discussed and compared with those previously reported for related acylhydrazones of aryl adehydes and acetone.     

NMR spectroscopic study of rotation around CC and C?N bonds in diene δ-aminocarbonyl compounds

A relatively fast rotation around the α,β carbon–carbon double bond at the equilibrium of geometrical isomers and a comparatively slow rotation around the carbon-nitrogen single bond in compounds of the type (X₁, X₂ are electron-attracting substituents) were detected and investigated by the NMR technique. The relationships between the free energies of activation for these rotational processes and the character of the substituents, the number of double bonds, solvents and concentration were studied.     

One-Pot Synthesis of Stable Phosphorus Ylides Using CH-Acid Compounds

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and di-tert-butyl acetylendicarboxylate, in the presence of antron, dimedone, indandion, and 3,5-dimethylbarbituric acid. These stable ylides exist in a solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

Dynamic 1H NMR study around the carbon-carbon single bond and partial carbon-carbon double bond in the two particular phosphorus ylides and in an enaminoester

Herein, a series of separate dynamic (1)H NMR effects are reported at different temperatures within a particular enaminoester involving a phenanthridine. These effects are attributed to restricted rotation around the two single bonds such as carbon-carbon (H(a)-C-C-H(b)) and nitrogen-carbon (NCCOOCH(3)). Activation energies (E(a)) for these interconversion processes in their rotational isomers are equal to 20 and 20 ± 1 kJ mol(-1), respectively. In addition, three dynamic (1)H NMR effects are investigated at different temperatures for a particular phosphorus ylide involving a 2-indolinone around the carbon-carbon single bond (H-C-C-PPh(3)) within the two Z- and E-rotational isomers and partial carbon-carbon double bond (OCH(3)-C=C-PPh(3)). Activation energies (E(a)) for these interconversion processes in rotational isomers are equal to 53, 63 and 73 ± 1 kJ mol(-1) , respectively. This behavior was also observed for other phosphorus ylide containing 2-mercaptobenzoxazole around the carbon-carbon single bond and partial carbon-carbon double bond with their relevant activation energies containing 13, 10 and 75 ± 1 kJ mol(-1), respectively.     

An Efficient One-Pot Synthesis and Temperature Dependence of NMR Spectra of Nitrogen-Containing Phosphorus Ylides

The addition of triphenylphosphine to dialkyl acetylenedicarboxylates in the presence of trifluoroacetamide, a NH acid, leads to stable crystalline phosphorus ylides in exellent yields. These stable ylides exist as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond, resulting from conjugation of the ylide moiety with the adjacent group.     

An Efficient Synthesis of Stable Phosphorus Ylides Derived from Hydantoin and 5,5-dialkylhydantoins

Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH-acids, such as hydantoin and 5,5-dialkylhydantoins. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

A facile synthesis of stable phosphorus ylides derived from 3,6‐dibromocarbazole and kinetic investigation of the reactions by UV spectrophotometry technique

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of NH‐acid, such as 3,6‐dibromocarbazole. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond, resulting from the conjugation of the ylide moiety with the adjacent carbonyl group. To determine the kinetic parameters of the reactions, they were monitored by UV spectrophotometry. The second‐order fits were drawn, and the values of the second‐order rate constant (k₂) were calculated using standard equations within the program. At the temperature range studied, the dependence of the second‐order rate constant (ln k₂) on reciprocal temperature was in a good agreement with the Arrhenius equation. This provided the relevant plots to calculate the activation energy of all reactions. Furthermore, useful information was obtained from studies of the effect of solvent, structure of reactants (different alkyl groups within the dialkyl acetylenedicarboxylates), and also the concentration of reactants on the rate of reactions. The proposed mechanism was confirmed according to the obtained results and a steady‐state approximation and the first step (k₂) of reaction was recognized as a rate‐determining step on the basis of the experimental data. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:723–732, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20501     

NMR study,theoretical calculations for assignment of the Z‐ and E‐isomers,and kinetics investigation of stable phosphorus ylides involving a 2‐mercapto‐4,6‐dimethyl pyrimidine

In the present work, NMR, theoretical, kinetics, and mechanism investigations were undertaken for a one‐pot condensation reaction between 2‐mercapto‐4,6‐dimethyl pyrimidine and dialkyl acetylenedicarboxylates in the presence of triphenyphosphine containing novel stable phosphorus ylides 4a–c . Herein, theoretical calculations have been employed for assignment of the most stable isomers (Z or E) of phosphorus ylides 4a,c by natural population analysis, atoms in molecules methods, and CHelpG keyword, in which E‐ 4(a, c) are more stable forms as the majors. The ¹H, ¹³C, and ³¹P NMR data of these ylides are consistent with results obtained from theoretical calculations. In addition, kinetic investigation of new ylides was undertaken by ultraviolet spectrophotometry. Useful information was obtained from studies of the effect of solvent, structure of reactants (different alkyl groups within the dialkyl acetylenedicarboxylates), and also the concentration of reactants on the rate of reactions. The proposed mechanism was confirmed according to the obtained results and a steady‐state approximation, and the first step (k₂) of the reaction was recognized as a rate‐determining step on the basis of the experimental data. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:462–474, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20632     

Triphenylphosphine Mediated Efficient Synthesis of 4-Substituted-1-methyl-2,5-dioxo-3-imidazolines

Summary.  Stable crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between 1-methylparabanic acid (1-methylimidazoline-2,4,5-trione) and dialkyl acetylenedicarboxylates in the presence of triphenylphosphine. These ylides exist in solution as a mixture of two geometric isomers. This is due to the restricted rotation around the carbon–carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. These ylides undergo smooth intramolecular Wittig reaction followed by an electrocyclic ring opening to produce dialkyl (E)-2-(1-methyl-2,5-dioxo-3-imidazolin-4-yl)-but-2-enedioates in good yields. Corresponding author. E-mail: isayavar@yahoo.com Received March 26, 2002; accepted (revised) April 24, 2002     

Triphenylphosphine-Catalyzed Simple Synthesis of Vinyl-Substituted Saccharins

Saccharin (1,1-dioxo-1,2-dihydro-1 u 6 -benzo[ d ]-isothiazol-3-one) undergoes a smooth reaction with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine to produce highly-functionalized salt-free sulfur-containing ylides in nearly quantitative yields. These stabilized phosphorus ylides exist as a mixture of two geometrical isomers as a result of restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. These ylides are converted to dialkyl 2-(1,1-dioxo-1 H -1 u 6 -benzo[ d ]-isothiazol-3-yl)-but-2-enedioates in boiling toluene.     

Chemoselective Synthesis of Stable Phosphorus Ylides from 6-Azauracil and Mechanistic Investigation of the Reaction by UV Spectrophotometry

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of NH-acids such as 6-azauracil. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group. To determine the kinetic parameters of the reactions, they were monitored by UV spectrophotometry. The second order fits were automatically drawn, and the values of the second order rate constants (k₂) were automatically calculated using standard equations. At the temperature range studied, the dependence of the second order rate constant (Ln k₂) on reciprocal temperature was in agreement with the Arrhenius equation. This provided the relevant plots to calculate the activation energy of all the reactions. Furthermore, useful information was obtained from studies of the effect of solvent, structure of reactants (different alkyl groups within the dialkyl acetylenedicarboxylates), and also concentration of reactants on the rate of reactions. The proposed mechanism was confirmed according to the obtained results, and a steady-state approximation and first step (k₂) of the reaction was recognized as a rate-determining step on the basis of experimental data.     

Through space spin-spin coupling <Superscript>19</Superscript>F-<Superscript>1</Superscript>H as the base for comparative analysis of conformational equilibrium in fluorine-substituted aryl vinyl selenides and sulfides

The analysis of long-range spin-spin coupling ¹⁹F-¹H and the other conformation-dependent parameters of ¹H NMR spectra shows that aryl vinyl selenides like aryl vinyl sulfides exist as mixtures of s-cis and s-trans rotational isomers. The combined data of ¹H and ¹³C NMR spectra reveal the increase in the torsional angle ϑ at the bond X-CH=CH₂ (X = S, Se) in selenides compared to sulfides due to diminished interaction energy of the unshared electron pairs of selenium with the π*-orbitals of the double bond as compared to analogous interaction in sulfides.