Studies on the Catalysis of Ene Reactions by Lithium Perchlorate in Different Solvents

Abstract

The catalytic effect of lithium perchlorate on ene reaction of cis-cyclooctene with diethyl azodicarboxylate, 4-phenyl-1,2,4-triazoline-3,5-dione and the metallo-ene reaction of diallyldibutyltin with diethyl azodicarboxylate has been studied in different solvents like acetonitrile, acetone, diethyl ether, dimethylformamide and ethyl acetate.     

Alkylation of quinoline and isoquinoline in the presence of LiCl

EEDQ and EEDI generated in situ by the reaction of quinoline and isoquinoline with diethyl pyrocarbonate was treated with alkylating reagents having an activated carbon such as diethyl malonate, ethyl acetoacetate etc. in the presence of 0.5 equiv of LiCl in acetonitrile to provide the corresponding alkyl dihydroquinolines and alkyl dihydroisoquinolines in high yields.     

Preparation of carbodiimides by the reaction of thioureas with diethyl azodicarboxylate

A new synthesis of disubstituted carbodiimides from N.N′-disubstituted thioureas, diethyl azodicarboxylate and triphenyl phosphine has been achieved. The intermediates of the reaction have been isolated and found to be 1:1 adducts of the thioureas and diethyl azodicarboxylate, N¹,N²-disubstituted—S—(N³,N⁴-biscarboethoxy)hydrazinoisothioureas which, on treatment with triphenyl phosphine at room temperature, afford the corresponding carbodiimides. Alternatively, the intermediates on heating under reflux in benzene or toluene, decompose to the carbodiimides, diethyl hydrazodicarboxylate and sulphur.     

Radiation copolymerization of vinyl acetate with the diethyl esters of maleic and fumaric acids

The radiation-induced copolymerization of vinyl acetate with diethyl maleate and with diethyl fumarate was investigated in the temperature range from ?40 to 90°C over a wide range of comonomer compositions. Both the rates of copolymerization and the molecular weights of the resulting copolymers were found to depend strongly on the initial comonomer compositions. The apparent activation energy was found to change at 13°C with an increase in temperature from a value of 1.76 kcal/mole to a value of 4.31 kcal/mole in the copolymerization with diethyl maleate, while in the case of the copolymerization with diethyl fumarate the apparent activation energy changed at 21°C from a value of 1.76 kcal/mole to a value of 5.98 kcal/mole. Scavenger studies indicate that a free-radical mechanism prevails over the entire temperature range investigated in the case of both copolymerizations.     

A simple and convenient procedure for the synthesis of 1-aminophosphonates from aromatic aldehydes

A simple, efficient, possible industrial process has been developed for the synthesis of 1-aminophosphonic acids from simple starting materials. As described below, treatment of aromatic aldehydes with ammonia and reaction with diethyl phosphite gives diethyl N-(arylmethylene)-1-aminoaryl methylphosphonates, which can be easily hydrolyzed to diethyl 1-aminoarylmethylphosphonates. This method is easy, rapid, and good yielding for the synthesis of 1-aminoalkylphosphonates from simple starting materials.     

Vibrational spectra and molecular conformation of diethyl fumarate and especially the maleate

Infrared and Raman spectra of diethyl maleate and diethyl fumarate were recorded in the liquid and solid states. From the spectral changes on phase transition the known conformational equilibrium s-trans/s-cis ? s-trans/s-trans in the case of dialkyl fumarates is confirmed, and the view that dialkyl maleates exist only in a single conformation is corrected. The observation of several bands in the vCC region of IR and Raman spectra of diethyl maleate, and significant intensity shifts in this region with phase transition prove the existence of at least two conformers in liquid dialkyl maleates.     

Reactions of 1,2-ethanedithiol and 2-mercaptoethanol with unsaturated derivatives of four-coordinate phosphorus acids

The reaction of 1,2-ethanedithiol with diethyl vinylphosphonate in the presence of EtONa occurs as the addition of the sulfhydryl group to the β-carbon atom of the substrate to give 1 : 1 and 1 : 2 adducts. The nucleophilic addition of 2-mercaptoethanol at the β position of the multiple bond of diethyl vinyl-, diethyl allenyl-, and diethyl prop-1-ynylphosphonates involves only the sulfhydryl group.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2156–2159, October, 2004.     

Comments on a novel synthesis of diethyl 1-aminoarylmethylphosphonates on the surface of alumina

Contrary to the literature statement we found that aromatic aldehydes react with diethyl phosphite and hexamethyldisilazane to give 1-(trimethylsilyloxy)-1-arylmethylphosphonates and not 1-amino-1-arylmethylphosphonate derivatives. Therefore, for preparation of diethyl N-arylidene-1-amino-1-arylmethylphosphonate, we recommend the direct reaction of hydrobenzamides with diethyl phosphite, instead of aromatic aldehydes, hexamethyldisilazane and alumina as catalyst on solid phase, as has been described previously (Sardarian, A. R.; Kaboudin, B. Tetrahedron Lett.1997, 38, 2543-2546).     

Organophosphorus chemistry. Part 19. Free-radical addition of dialkyl phosphites to polyfluoro-olefins

An improved procedure for the peroxide-catalysed addition of dialkyl phosphites to tetrafluoroethylene is described, and the reactions of diethylphosphite with chlorotrifluoroethylene, 1,1-difluoroethylene,perfluoropropene, and 3,3,3-trifluoropropene have been investigated and found to yield diethyl 2-chloro-1,1,2-trifluoroethylphosphonate, diethyl 2,2-difluoroethylphosphonate, an 80:20 mixture of diethyl 2$\text{H}$-hexafluoro-$\text{n}$-propylphosphonate and diethyl 1$\text{H}$-hexafluoropropyl-2-phosphonate, and diethyl 3,3,3-trifluoropropyl-1-phosphonate, respectively.     

Reactions of some nitrosoperfluoroalkanes with trimethylsilyl phosphites

Nitrosotrifluoromethane or nitrosopentafluoroethane reacted with trimethylsilyl diethyl or tris(trimethylsilyl) phosphite to give phosphato-fluorocarbimino- or phosphato-trifluoroacetimino-phosphonates and fluorotrimethylsilane. Some intermediate compounds could be detected by NMR spectroscopy, namely, diethyl (N-trimethylsiloxy-N-trifluoromethyl)- or diethyl (N-trimethylsiloxy-N-pentafluoroethyl)amidophosphate and difluorocarbimino diethyl phosphate. © 1996 John Wiley & Sons, Inc.     

Selective Hydrogenation of Diethyl Disulfide to Ethanethiol in the Presence of Sulfide Catalysts

The gas-phase reaction of diethyl disulfide hydrogenation at atmospheric pressure in the presence of supported transition metal sulfides was studied. The reaction of diethyl disulfide with hydrogen at T = 200°C resulted in ethanethiol, and the selectivity to ethanethiol was no lower than 94%. The selectivity decreased at a higher temperature because of diethyl disulfide decomposition to ethylene and hydrogen sulfide. The reaction of diethyl disulfide in the presence of hydrogen occurred at a higher rate and selectivity than that in an atmosphere of helium. The activity of metal sulfides supported on aluminum oxide was higher than on the other studied supports—aluminosilicate, silica gel, and a carbon support. Metal sulfides supported on Al₂O₃ were arranged in the following order according to their activity: Rh > Ru > Mo Pd > Ni > W. Bimetallic catalysts were less active than monometallic catalysts. The activity of catalysts increased with the sulfide sulfur content; the partial reduction of metal sulfides also increased the catalytic activity.     

Solventless DBU-promoted Mannich-type reactions of α-amido p-tolylsulfones with diethyl fluoromalonates and diethyl malonates

Mannich-type reactions of α-amido p-tolylsulfones with diethyl fluoromalonates and diethyl malonates, respectively in presence of catalytic amount of DBU have been developed. A variety of α-amido p-tolylsulfones prepared from aromatic and aliphatic aldehydes reacts with diethyl fluoromalonates and diethyl malonates, respectively under mild reaction conditions to afford α-fluoro β-amino esters and β-amino esters in moderate to good yield.     

TiCl4 and Grignard reagent-promoted ring-opening reactions of various epoxides: synthesis of γ-hydroxy-α,α-difluoromethylenephosphonates

A straightforward methodology for the synthesis of diethyl γ-hydroxy-α,α-difluoromethylenephosphonates is reported. In the presence of titanium tetrachloride, epoxide ring-opening reactions occurred upon treatment with lithium diethyl difluoromethylenephosphonate. When diethyl 3,4-epoxy-1,1-difluorobutylphosphonate was reacted with TiCl₄ and Grignard reagents, the corresponding halohydrins were obtained in very good yields.     

Synthesis of phosphorylated isoindolinone derivatives

The synthesis of diethyl [2-(2-alkyl-3-oxo-2,3-dihydro-1H-isoindol-1-yl)ethyl]phosphonates and diethyl [3-(2-alkyl-3-oxo-2,3-dihydro-1H-isoindol-1-yl)propyl]phosphonates, via metallation (sec-BuLi) of N-substituted isoindolin-1-ones and then the reaction of the generated lithiated species 4 with diethyl vinylphosphonate or diethyl 3-bromopropylphosphonate, respectively, is described.     

Application of 1-Azidoalkylphosphonates in the Synthesis of Phosphonodipeptides and Other N-Substituted Aminophosphonates

Efficient synthesis of diethyl 1-(isothiocyano)alkylphosphonates, and N-derivatives of diethyl 1-aminoalkylphosphonates as well as phosphonodipeptides were developed using diethyl 1-azidoalkylphosphonates as starting materials.     

Stobbe-like condensation reactions of the anion of diethyl (2-carboethoxy)benzylphosphonate with some aromatic and heterocyclic aldehydes

Deprotonation of diethyl (2-carboethoxy)benzylphosphonate using sodium ethoxide followed by reaction of the carbanion with furfural or aryl aldehydes gives diethyl (E)-1-(2′-carboxyphenyl)-1-phosphono-2-arylethenes that are formed via intramolecular Stobbe-like condensation reactions.     

Chromatographic determination of phthalic acid esters as an indicator of adulterated cognacs and cognac spirits

Based on the study performed, a conclusion was drawn that a system of procedures should be introduced into the practice of arbitration laboratories in order to identify the authenticity of cognacs and cognac spirits. These procedures were exemplified in the identification of diethyl phthalate in cognacs. Factors responsible for the falsely positive detection of diethyl phthalate in cognacs and cognac spirits were revealed. A substance that has a retention time equal to that of diethyl phthalate was identified as monoethyl succinate. As an example, recommendations were given for revealing adulterated cognac samples upon the detection of phthalic acid esters in them (including diethyl phthalate, which is a marker of denaturation). Sources of the contamination of test samples with diethyl phthalate were identified; an algorithm was developed for distinguishing between diethyl phthalate as an impurity component and diethyl phthalate added to an alcohol as a denaturation marker.     

Liquid-liquid equilibria of (water + butyric acid + diethyl succinate or diethyl glutarate or diethyl adipate) ternary systems

Liquid-liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + butyric acid (2) + diethyl succinate or diethyl glutarate or diethyl adipate (3)} at 298.2 K and 101.3 ± 0.7 kPa. The relative mutual solubility of butyric acid is higher in the diethyl succinate or diethyl glutarate or diethyl adipate layers than water layers. The consistency of the experimental tie-lines was determined through the Othmer-Tobias correlation equation. The LLE data were correlated with NRTL model, indicating the reliability of the NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (α = 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents.     

Structure of the trimer of acrolein diethyl acetal

Summary The product formed by the condensation of acrolein diethyl acetal under the influence of BF₃ etherate is a trimer of composition C₂₁H₄₂O₆ and is 2-ethoxy-4-(1-ethoxyallyl)glutaraldehyde diethyl acetal. A mechanism is proposed for its formation via a quasi-aromatic complex with subsequent cyclic electron transfer.     

Conjugate reduction of α,β-unsaturated esters and amides with tributyltin hydride in the presence of magnesium bromide diethyl etherate

We report herein that the conjugate reduction of α,β-unsaturated esters and amides, such as aryl acrylates, pantolactone esters of acrylic acids, diethyl itaconate and N-crotonylcamphorsultam, with tributyltin hydride proceeded in moderate to high yields in the presence of magnesium bromide diethyl etherate. The effect of metal halide enhancing the yields is also described.