A Simple Synthesis of Stable Heterocyclic Phosphorus Ylides Derived from NH-Acids

Crystalline phosphorus ylides are obtained in excellent yields from the addition reaction between triphenylphosphine, dimethyl acetylenedicarboxylate and strong NH-acids, such as 2-acetylpyrrole, indole, ethyl 3-indolylglyoxalate and N -benzyl-2-pyrrolylglyoxamate. Dynamic NMR effects are observed in the 1 H NMR spectra of stabilized ylides obtained from 2-acetylpyrrole and indole ( j G p = 67.1 and 68.8 kJmol m 1 respectively) and are attributed to restricted rotation around the carbon-carbon partial double bond resulting from conjugation of the ylide moiety with the adjacent carbonyl group.     

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.     

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.     

Phosphorus Ylides in the Coordination Sphere of Transition Metals: An Inventory

Phosphorus ylides are not only classical reagents in organic chemistry, but also play an increasingly important role as novel components in organometallic compounds. These metallic “ylide complexes” are either synthesized from “preformed ylides” and coordination compounds by addition or substitution, on the building block principle, or they are formed, in sometimes complicated reactions, from phosphanes, metal complexes, and C₁ substrates in the coordination sphere of the metals. The resulting metal-carbon bonds are greatly modified in their properties by the immediate presence of the phosphonium center and often belong to the most stable of M-C structural units. The metal can come from any group of the periodic table, including the lanthanoids and actinoids. Numerous preparative and structural studies are gradually enabling us to gain an overall picture of the scope of this area of research.     

Three-Component Reaction of Triphenylphosphine,Acetylenic Esters,and Arylsulfonyl Hydrazides or Aryl Hydrazines: An Efficient One-Pot Synthesis of Stable β-Nitrogen-Substituted Phosphorus Ylides

The three-component reaction between dialkyl acetylenedicarboxylates and triphenylphosphine in the presence of arylsulfonyl hydrazides or aryl hydrazines produces highly functionalized, salt-free phosphorus ylides in excellent yields.     

Synthesis of Stable Multifunctional C-Phosphonio Phosphorus Vinyl Ylides

Trifluoromethanesulfonic acid reacts at 240 K with bis[bis(diisopropylamino)phosphino]diazomethane, 1, affording the corresponding cationic (phosphino)(P-hydrogenophosphonio)diazomethane derivative 2, which eliminates dinitrogen above 250 K, leading to (phosphino)(phosphonio)carbene 3 isolated in 76% yield (mp 88 degrees C). Bis(diisopropylamino)phosphenium salt 5a adds at 240 K to P-chlorodiazomethylenephosphorane 4 giving (phosphino)(P-chlorophosphonio)diazo derivative 6a, which leads, after N(2) elimination, to the corresponding carbene 7a. Addition of potassium tert-butoxide to 3 gives rise to the transient diphosphinocarbene 8, which rearranges into phosphaalkene 9. Sodium tetrafluoroborate, tert-butyllithium, and tributyltin hydride react with 3 to afford P-fluoro-P'-hydrogenocarbodiphosphorane 10, P,P'-dihydrogenocarbodiphosphorane 12, and stannyl-substituted methylene salt 15, respectively. tert-Butyl isocyanide reacts with phosphoniocarbene 3 giving heterocycle 19, whereas with carbene 7 phosphonioketeneimine 18 and bis(diisopropylamino)phosphinonitrile are obtained.     

Three-Component One-Pot Synthesis of Polyhydroacrodine Derivatives in Aqueous Media

9,10-Diaryldecahydroacridine-1,8-diones were synthesized by a three-component reaction of aromatic aldehydes, aromatic amines, and 5,5-dimethyl-1,3-cyclohexanedione using sodium 1-dodecanesulfonic (SDS) as the catalyst in aqueous media. The key intermediates before the cyclization step were obtained and characterized. The structures of all the products were determined by IR and ¹H NMR spectra and further confirmed by single-crystal x-ray diffraction analysis.     

A Facile Synthesis of Stable Phosphorus Ylides Containing Chlorine and Sulfur Derived from 6-Chloro-2-benzoxazolethiol and 2-Chloro-phenothiazine

Stable crystalline phosphorus ylides containing chlorine and sulfur were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylene-dicarboxylates in the presence of 6-chloro-2-benzoxazolethiol and 2-chloro-phenothiazine. These stable ylides exist in solution as a mixture of two geometrical isomers. This is caused by the conjugation of the ylide moiety with the adjacent carbonyl group, which results in a restricted rotation around the respective carbon-carbon bond.     

Three-Component Reaction of Triphenylphosphine,Dimethyl Acetylenedicarboxylate,and Aldehyde Benzoylhydrazones: An Efficient One-Pot Synthesis of Stable Phosphorus Ylides

Protonation of the reactive 1:1 intermediate produced in the reaction between dimethyl acetylenedicarboxylate and triphenylphosphine by benzoylhydrazones leads to vinylphosphonium salts, which undergo Michael addition with the conjugate base of the NH acid to produce highly fanctionalized, salt-free phosphorus ylides in excellent yields.     

A Facile One-Pot Synthesis of Vinpocetine

A one-pot synthesis of vinpocetine from vincamine was established. Lewis acids caused transesterification and/or dehydration of vincamine in EtOH. FeCl₃ catalyzed both transesterification and dehydration while Ti(OEt)₄ selectively catalyzed transesterification.     

Indium-mediated Facile Synthesis of （6-Chloropyridine-3-yl）methyl Heterocyclic Thioether Derivatives in Aqueous Media

A series of substituted (6-chloropyridine-3-yl)methyl heterocyclic thioether derivatives were prepared by indium mediating in water. The preliminary biological tests showed that compound 3d exhibited good antiviral activity.     

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.     

Synthesis of a New Class of Highly Functionalized Phosphorus Ylides Containing Heterocyclic Compounds

The zwitterionic intermediate generated from the reaction of triphenylphosphine with electron deficient acetylenic compounds was trapped by various NH acids. The synthesis resulted in a new class of highly functionalized heterocyclic compounds. Some of the reactions produced E and Z isomers. And the stability and transformation of them were studied by dynamic ¹H NMR and density functional theory (DFT) calculations.     

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.     

Facile One-Pot Synthesis of 1,2,3,4-Tetrahydroquinoline-3-carboxylic Acids and Their Heterocyclic Analogs

A facile one-pot method for the synthesis of 1,2,3,4-tetrahydroquinoline-3-carboxylic acids and their heterocyclic analogs based on the tert-amino effect. A set of 1,2,3,4-tetrahydroquinoline-3-carboxylic acids was readily prepared starting from various ortho-dialkylaminoaldehydes and Meldrum's acid using Me₃SiCl in dimethylformamide (DMF) solution.     

Synthesis,Isolation and Crystal Structures of the Metalated Ylides [Cy3P-C-SO2Tol]M (M = Li,Na, K)

The preparation and isolation of the metalated ylides [Cy₃PCSO₂Tol]M ( ^Cy1-M ) (with M = Li, Na, K) are reported. In contrast to its triphenylphosphonium analogue the synthesis of ^Cy1-M revealed to be less straight forward. Synthetic routes to the phosphonium salt precursor ^Cy1 - H₂ via different methods revealed to be unsuccessful or low-yielding. However, nucleophilic attack of the ylide Cy₃P = CH₂ at toluenesulfonyl fluoride under basic conditions proved to be a high-yielding method directly leading to the ylide ^Cy1-H . Metalation to the yldiides was finally achieved with strong bases such as nBuLi, NaNH₂, or BnK. In the solid state, the lithium compound forms a tetrameric structure consisting of a (C–S–O–Li)₄ macrocycle, which incorporates an additional molecule of lithium iodide. The potassium compound forms a C₄-symmetric structure with a (K₄O₄)₂ octahedral prism as central structural motif. Upon deprotonation the P–C–S linkage undergoes a remarkable contraction typical for metalated ylides.     

A Simple Synthesis of Stable Phosphorus Ylides Derived from 2-Benzoxazolinone and 2-Mercaptobenzoxazole

The reaction of triphenylphosphine with dialkyl acetylenedicarboxylates in the presence of a strong SH-acid or NH-acid, such as 2-mercaptobenzoxazole and 2-benzoxazolinone, has been studied. In some cases, stable phosphorus ylides are obtained in excellent yields. The ylide moiety of these compounds is strongly conjugated with the adjacent carbonyl group, and the rotation about the partial double bond in (E) and (Z) geometrical isomers is slow on the NMR time scale at an ambient temperature. Thus, these exist as a mixture of geometrical isomers.     

A Novel Synthesis of Fused Heterocyclic Sulfones

The applicability and synthetic potency of the novel reagent diethyl 2‐aryl‐3‐phenylsulfonylpropen‐1,1‐dicarboxylate 3 is reported. Compound 3 proved to be a key precursor in heterocyclic sulfones syntheses. Chemical and spectroscopic evidence for the structure of the newly synthesized compounds are described.     

One-Pot Synthesis of Tetrahydrobenzo-[b]-pyran Derivatives in Aqueous Media

In modem organic chemical research, 4H-benzo-[b]-pyran and their derivatives have attracted strong interest due to their useful biological and pharmacological properties. Herein, we report a clean one-pot synthesis of 2-amino-3-cyano-4-aryl-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydro-benzo-[b]-pyrans from aromatic aldehyde, malononitrile and 5,5-dimethyl-1,3-cyclohexadione using hexadecyl trimethyl ammonium bromide (HTMAB) as the catalyst. This method provides several advantages such as high yield, simple work-up procedure and environmental friendliness. All the products were characterized by 1H NMR and IR analyses.