An Efficient,One-Pot Synthesis of Dialkyl 5-Hydroxy-4-aryl-2,5-dihydrofuran-2,3-dicarboxylate Derivatives

The reaction between arylglyoxalmonohydrates, dialkyl acetylenedicarboxylates, and triphenylphosphine is described as a simple and efficient method for the synthesis of 5-hydroxy-4-aryl-2,5-dihydrofuran-2,3-dicarboxylate derivatives.     

One-Pot,Three-Component Synthesis of Dialkyl 1,2-Dihydroquinoline-2,3-Dicarboxylates from Triphenylphosphine,Acetylenic Esters,and Amide Derivatives of 2-Aminobenzaldehyde in Aqueous Acetone

Abstract

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by amide derivatives of 2-aminobenzaldehyde in the mixture of acetone-water (3:1) leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce the corresponding stabilized phosphorus ylides. An intramolecular Wittig reaction of the stabilized phosphorus ylide group with the aldehyde group leads to the corresponding dialkyl 1,2-dihydroquinoline-2,3-dicarboxylates.     

Multicomponent Synthesis of 2,5-Dioxo- and 4-Aryl-5-oxo-2-thioxo-1,2,3,4,5,6,7,8-octahydroquinazolines

Ten 2,5-dioxo- and 4-aryl-5-oxo-2-thioxo-1,2,3,4,5,6,7,8-octahydroquinazolines have been synthesized in three-component interactions of 1,3-cyclohexanedione or dimedone, urea or thiourea, and substituted benzaldehydes (3-bromo-, 4-bromo-, 4-fluoro-, 4-methoxy-, 3,4-methylenedioxy-, and 3-nitro-). 9-Aryl-4,5-dioxo-1,2,3,4,5,6,7,8-octahydro-9H-xanthenes were also formed in these reactions.     

Three-Component Reaction of Triphenylphosphine,Dialkyl Acetylenedicarboxylate,and 2-Aminothiazole or 2-Aminobenzothiazole in the Presence of Arylglyoxals: An Efficient One-Pot Synthesis of Highly Functionalized Pyrroles

A new and efficient one-pot synthesis of polysubstituted pyrrole derivatives by three-component reaction of dialkyl acetylenedicarboxylates, triphenylphosphine, 2-aminothiazole or 2-aminobenzothiazole in the presence of arylglyoxals is described. The reactions were performed in dichloromethane at room temperature and neutral conditions and afforded good yields of products.     

Triphenylphosphine-Catalyzed Stereoselective Synthesis of Alkyl 3-(2-Naphthylsulfanyl)-2-propenoate from Alkyl Acetylenecarboxylates and 2-Naphthalenethiol

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and alkyl acetylenecarboxylates by 2-naphthalenethiol, leads to vinyltriphenylphosphonium salts, which undergo an addition–elimination reaction to produce the corresponding S-vinyl thioethers. The NMR spectra indicated that the compounds contained two stereoisomers for each S-vinyl thioether; their ratio was determined on the basis of ¹ H NMR spectra. The reaction is fairly stereoselective.     

Triphenylphosphine-Catalyzed Synthesis of Stable,Functionalized 2H-Oxetes

Triphenylphosphine underwent Michael addition to dialkyl acetylenedicarboxylate and subsequently to the carbonyl group of α-haloketones. Then, these compounds were cyclized to produce the unstable 1, 3-diionicphosphorus compound, which spontaneously lost triphenyl phosphine, and was converted to the functionalized oxetes derivatives.     

Synthesis and characteristics of the mass spectra of 2,5-dimercapto-2,5-dimethyltetrahydrothiophene

2,5-Dimercapto-2,5-dimethyltetrahyrothiophene was synthesized by the reaction of 1-iodopropan-2-one with hydrogen sulfide in an ether solution of hydrogen chloride at-70°C. Its structure was established by mass spectrometry, ¹H and ¹³C NMR spectroscopy. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 216–219, February, 2007.     

Synthesis of Dialkyl 4-Ethoxy-2,5-dihydro-1-(9,10-dihydro-9,10-dioxoanthracen-1-yl)-5-oxo-1H-pyrrole2,3-dicarboxylates

Abstract

The reaction of ethyl 9,10-dihydro-9,10-dioxoanthracen-1-yl-carbamoyl-formate with dialkyl acetylenedicarboxylates in the presence of triphenylphosphine leads to dialkyl 4-ethoxy-2,5-dihydro-1-(9,10-dihydro-9,10-dioxoanthracen-1-yl)-5-oxo-1H-pyrrole-2,3-dicarboxylates in fairly good yields. A dynamic NMR effect is observed as a result of restricted rotation around the single bond linking the anthraquinone moiety and the heterocyclic ring system, which is attributed to the interaction between the pyrrole residue and the peri C═O group.     

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     

One-Step Synthesis of Electron-Poor Alkenes from Triphenylphosphine,Acetylenic Esters, 2,2,2-Trichloroethanol,and Ninhydrin

Protonation of the highly reactive 1:1 intermediates, produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, by 2,2,2-trichloroethanol leads to vinyltriphenylphosphonium salts, which undergo a Michael addition reaction with a conjugate base to produce the corresponding chlorine-containing stabilized phosphorus ylides. An intermolecular Wittig reaction of the chlorine-containing stabilized phosphorus ylides with ninhydrin leads to the corresponding highly electron-poor chlorine-containing alkenes.     

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 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.     

Synthesis of Highly Functionalized 1-Azadienes and Ketenimines

Summary. The 1:1 reactive intermediate generated by the addition of alkyl isocyanides to dialkyl acetylenedicarboxylates was trapped by fairly strong NH-acids such as carbazole, indole, or pyrrole to yield highly functionalized 1-azadienes and ketenimines.     

Design and Optimization of Ecofriendly One-Pot Synthesis of 2,4,5-Triaryl-1H-imidazoles by Three-Component Condensation Using Response Surface Methodology

Phase-transfer-catalyzed, highly versatile, and high-yielding protocol for the synthesis of 2,4,5-triaryl-1H-imidazoles was developed through response surface methodology (RSM). The effects of different solvents, reaction paths, and phase-transfer catalysts (PTCs) in different concentrations were envisioned. Three independent variables (catalyst, catalyst loading, and solvent volume) identified by one-factor-at-a-time (OFAT) study were screened through full factorial design at two levels. The analysis of variance results suggested the significance of catalyst PEG400 and solvent glacial acetic acid at 5 h reaction. The optimum reaction conditions suggested by the RSM were the use of PEG400 (10.61 mol%) and glacial acetic acid (10.71 mL) for 5 h cycloocondensation. The experimental yield of 4,5-diphenyl-2-nitrophenyl-1H-imidazole (97%) was in agreement with predicted yield (97.5%).     

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.     

Reactions of metallated 1-hydroxy-2,2,4,5,5-pentamethyl-2,5-dihydro-1H-imidazole with functionalized nitroxyl radicals derived from 2,5-dihydro-1H-imidazole and 2,5-dihydro-1H-imidazole 3-oxide

The reactions of the dianion generated from 1-hydroxy-2,2,4,5,5-pentamethyl-2,5-dihydro-1H-imidazole under the action of lithium diisopropylamide with nitroxyl radicals derived from 2,5-dihydro-1H-imidazole or 2,5-dihydro-1H-imidazole 3-oxide and containing the ester, aldehydo, cyano, or imino groups afforded biradicals, including those containing the enamino ketone and enamino imine functions. The reactions of this dianion with nitriles derived from 2,5-dihydro-1H-imidazole 3-oxide gave rise to an enamino nitrile, i.e., electrophilic cyanation formally occurred.     

Synthesis of Functionalized Pyrido[1,2-f]phenanthridines from Phenanthridine,Activated Acetylenes,and Arylidenemalononitriles

The zwitterions generated from phenanthiridine and dialkyl acetylenedicarboxylates (DAADs) react with a variety of arylidenemalononitriles, affording substituted pyrido[1,2-f]phenanthridines.     

Synthesis of 5-[2-(Phenoxy)ethyl] Derivatives of 6-Methyluracil, 6-Methyl-2-thioxo-2,3-dihydro-1H-pyrimidin-4-one,and 2-Imino-6-methyl-2,3-dihydro-1H-pyrimidin-4-one

A synthesis of novel derivatives of 6-methyluracil, 6-methyl-2-thioxo-, and 2-imino-6-methyl-2,3-dihydro-1H-pyrimidin-4-one containing a 2-(phenoxy)ethyl substituent at position 5 of the pyrimidine ring has been carried out. It was found that 5-[2-(phenoxy)ethyl] derivatives of 6-methyl-2-thioxo- and 2-imino-6-methyl-2,3-dihydro-1H-pyrimidin-4-one are obtained by the condensation of the corresponding ethyl 3-oxo-2-(2-phenoxyethyl)butanoates with thiourea or guanidine. 6-Methyl-5-[2-(phenoxy)ethyl]uracils can be prepared by treating 6-methyl-5-[2-(phenoxy)ethyl]-2-thioxo-2,3-dihydro-1H-pyrimidin-4-ones with an excess of aqueous monochloroacetic acid solution. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1213–1217, August, 2005.     

Vinyltriphenylphosphonium Salt Mediated One-Pot Stereoselective Synthesis of Dialkyl ( E )-2-(2-methyl-5-oxo-1-cyclopentenyl)-2-butenedioates

Protonation of the highly reactive 1:1 intermediates produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by 2-hydroxy-3-methyl-2-cyclopenten-1-one leads to vinyltriphenylphosphonium salts, which undergo an intramolecular Wittig reaction to produce the corresponding cyclobutene derivatives. The cyclobutene derivatives are not isolable and undergo electrocyclic ring-opening reactions in CH 2 Cl 2 at room temperature to produce dialkyl ( E )-2-(2-methyl-5-oxo-1-cyclopentenyl)-2-butenedioates in moderate yields.     

Interaction of 1-Benzyl-4-benzoyl-5-phenyl-2,3-dihydro-2,3-pyrroledione with Ketene Diethylacetal: Synthesis and Crystal and Molecular Structure of 1-Benzyl-4-benzoyl-3-hydroxy-5-phenyl-5-ethoxycarbonylmethyl-2,5-dihydro-2-pyrrolone

1-Benzyl-4-benzoyl-5-phenyl-2,3-dihydro-2,3-pyrroledione reacts with ketene diethylacetal, forming 1-benzyl-4-benzoyl-3-hydroxy-5-phenyl-5-ethoxycarbonylmethyl-2,5-dihydro-2-pyrrolone, whose crystal and molecular structure was studied by XRD.