Reactions of Aliphatic Diazo Compounds: V. Reaction of Methyl Diazoacetate with Imides of Itaconic Acid

Methyl diazoacetate regioselectively adds to N-substituted imides of itaconic acid to afford 2-pyrazolines, methyl 7-aryl-6,8-dioxo-1,2,7-triazaspiro[4.4]non-2-ene-3-carboxylates that in reaction with halogens (Cl₂, Br₂) yield methyl 5-aryl-1-halo-4,6-dioxo-5-azaspiro[2.4]heptane-1-carboxylates as a mixture of syn- and anti-isomers.     

Reactions of Aliphatic Diazo Compounds: III. Reaction of Ethyl Diazoacetate with 1,3-Diarylpropenones

Ethyl diazoacetate adds to 1,3-diarylpropenones in a regioselective fashion to give intermediate 4,5-dihydro-3H-pyrazole derivative; 1,3-hydride shift in the latter leads to formation of isomeric ethyl 4-aryl- 5-aroyl-4,5-dihydro-1H-pyrazole-3-carboxylate and ethyl 4-aryl-3-aroyl-4,5-dihydro-1H-pyrazole-5-carboxylate at a ratio of 5:1. Thermolysis of these products is not stereospecific; as a result, three isomeric substituted ethyl cyclopropanecarboxylates and 2-pyranone derivative are formed.     

Reactions of Diazo Compounds with Imines. Preliminary communication

The [Rh₂(OAc)₄]-catalyzed addition of methyl diazoacetate to N-benzylideneaniline ( 1a ) afforded the imine cis- 2 in 35% yield. Under catalysis by chiral Rh^II catalysts, however, only racemic 1a was produced, and the yield was low. In the presence of dimethyl maleate, aziridine formation was suppressed, and an intermediate ylide 6 was trapped as cycloadduct 7 . No aziridines were obtained, however, from 1b, 1c , and 3 . The iminium salt 8 reacted with (trimethylsilyl)diazomethane in the absence of [Rh₂(OAc)₄] via dipolar cycloaddition followed by extrusion of N₂ to 10 .     

Reactions of Aliphatic Diazo Compounds: VI. Reactions of Diazomethane and Ethyl Diazoacetate with (E)-2-Arylmethylene-1,2,3,4-tetrahydronaphthalen-1-ones

Diazomethane and ethyl diazoacetate add to (E)-2-arylmethylene-1,2,3,4-tetrahydronaphthalen-1-ones in a regio- and stereoselective fashion, yielding the corresponding 4'-aryl-1,2,3,4,4',5'-hexahydro-3'H-naphthalene-2-spiro-3'-pyrazol-1-ones. The products formed by addition of ethyl diazoacetate undergo isomerization into 4,5-dihydro-1H-pyrazole derivatives.     

Diazo Reactions with Unsaturated Compounds: VII. Vinyl p-Methylphenyl and Vinyl p-Nitrophenyl Ethers in the Meerwein Reaction

Vinyl p-methylphenyl ether in aqueous acetone at pH 3-4 in the presence of catalytic amounts of copper(II) chloride reacts with arenediazonium chlorides to form arylacetaldehydes. Vinyl p-nitrophenyl ether under the same conditions fails to react with arenediazonium chlorides.     

Unusual Reaction of Diazo Compounds with Enamines

Transition metal catalyzed decomposition of diazo compounds and consequent transformations constitute various synthetic useful reactions in the past decades. The catalytic addition of diazo compounds to olefins generally provides cyclopropanes in high yield. However the reaction of electron-rich enamines with diazo compounds gave variable results. Wenkert et al. reported the reaction of enamines with ethyl diazoacetae (EDA) in the presence of cuprous chloride or silver oxide unexpectedly gave…     

Microwave Assisted Synthesis of Diosgenin Esters of Maleic and Itaconic Acids

Diosgenin monomaleate and diosgenin monoitaconate were prepared by the esterification of diosgenin with maleic and itaconic anhydride, respectively, in toluene using p-toluenesulphonic acid as catalyst. A domestic microwave oven was modified and used for the synthesis of both products. The reaction time for consuming all the diosgenin according to thin-layer chromatography (TLC) was reduced by around 90% in the synthesis of monomaleate of diosgenin as well as in the synthesis of monoitaconate of diosgenin in comparison with conventional heating, whereas the monomaleate of diosgenin yield increased from 43 to 80–85% and the monoitaconate of diosgenin yield from 34 to 95% under the same experimental conditions. It was easier to purify the diosgenin monoitaconate than the diosgenin monomaleate. Both products were characterized by NMR and FTIR spectroscopy.     

Diazo Reactions with Unsaturated Compounds: VI. Reaction of 1-(p-Nitrophenylsulfonyl)buta-1,3-diene with Arenediazonium Chlorides

1-(p-Nitrophenylsulfonyl)buta-1,3-diene reacts with arenediazonium chlorides in aqueous acetone in the presence of catalytic amounts of CuCl₂·2H₂O to form 1-(p-nitrophenylsulfonyl)-4-aryl-3-chloro-1-bu- tenes. In the presence of SO₂, 1-(p-nitrophenylsulfonyl)buta-1,3-diene does not react with arenediazonium chlorides.     

Reaction of Aliphatic Diazo Compounds with Dinitrogen Trioxide. A Facile route to 3,4-Disubstituted 1,2,5-Oxadiazole-2-oxides(Furoxans)

As part of our continuing studies¹of the chemistry of diazo compounds, we have investigated the reaction of α-diazosulfones, α-diazoketones and ethyl diazoacetate with dinitrogen trioxide. When a solution of the diazo compound is allowed to react at 0–5° with excess n₂O₃ ² in CH₂Cl₂, and almost instantaneous evolution of a gas (presumably nitrogen) is observed. Work-up afforded 3,4–disubstituted furoxans (I–VII, see Table) in good Yields.     

Phosphine-Catalyzed Reactions of Imides and Hydrophosphoryl Compounds Addition to Divinyl Sulfone

Russian Journal of General Chemistry - An efficient method for the phosphine-catalyzed bisaddition of P(O)H compounds and cyclic imides to divinyl sulfone has been developed. The reaction proceeds...     

Kinetic Investigations of Reactions with Maleic Anhydride Copolymers and Model Compounds

Alternating copolymers that contain maleic anhydride (MAn) as a component occur in two different stereochemical configurations which are differentiated by their reactivity. Model compounds, 2, 3-dialkylsuccinic acids and their anhydrides, were investigated and it was demonstrated that there is a distinct difference between threo and erythro configurations in their chemical and physical behavior. Both configurations also occur in the alternating copolymers. Beside the model compounds, the alternating copolymers ethylene-MAn, propylene-MAn, and styrene-MAn were investigated in their reactions with amines, alcohols, and water (hydrolysis). The cis configurations showed the higher reaction rates. Reactions of the anhydride moieties with equimolar amounts of aniline, ethanol, and water demonstrated that reactions follow second-order rate laws. With excess reactant, the reaction follows a pseudo-first-order rate law. The rate constants depend on the degree of polymerization and on the comonomer. Increasing steric hindrance and molecular weight lead to a decrease of the reaction rate. Catalysis of the hydrolysis reaction by tertiary amines results in similar rate constants for the configurations of the substituted succinic acid anhydrides. The reasons are discussed.     

Triarylborane‐Catalyzed Alkenylation Reactions of Aryl Esters with Diazo Compounds

Herein we report a facile, mild reaction protocol to form carbon–carbon bonds in the absence of transition metal catalysts. We demonstrate the metal‐free alkenylation reactions of aryl esters with α‐diazoesters to give highly functionalized enyne products. Catalytic amounts of tris(pentafluorophenyl)borane (10–20 mol %) are employed to afford the C=C coupled products (31 examples) in good to excellent yields (36–87 %). DFT studies were used to elucidate the mechanism for this alkenylation reaction.     

Synthesis of Substituted Phosphonates and Their Reactions with Carbonyl Compounds

Abstract

The reaction of the derivatives of 3-phenyl-3-chloro-2-oxopropionic acid with the trivalent phosphorus compounds has been studied. The esterification or amidation of this acid have been shown to influence the course of reaction with Ph₃P. In the reaction with esters enolphosphonium salts are produced, ketophosphonium salts are obtained when amides are involved. Properties of these compounds have also been studied in the Wittig reaction. 3-(α-chlorobenzyl)-2-oxoquinoxaline which reacted with trialkyl phosphates (Arbuzov reaction) has been synthesized. These phosphonates are obtained in nearly quantitative yields, in alkaline conditions (Horner-Emmons reaction) they react smoothly with aromatic aldehydes to give the substituted vinylyuinoxalines.