Synthesis of Enol Methyl Ethers of 3-Acetyl-6,6-dimethyltetrahydrothiopyran-2,4-dione and Their Reactions with Amines

The reaction of 3-acetyl-6,6-dimethyltetrahydrothiopyran-2,4-dione with diazomethane furnishes a mixture of 3-acetyl-6,6-dimethyl-4-methoxy-5,6-dihydro-2H-thiopyran-2-one and 3-acetyl-6,6-dimethyl- 2-methoxy-5,6-dihydro-2H-thiopyran-4-one in 2:3 ratio, whereas in reaction with dimethyl sulfate in the presence of potassium carbonate forms a mixture of the same products in 9:1 ratio. In both reactions the overall yield of ethers amounts to 50%. Treating of regioisomeric enol methyl ethers with pyrrolidine, o-toluidine, and allylamine provides the corresponding endocyclic enaminodiketones.     

Regioselective Synthesis of 4-Acetyl-and 5-Acetyl-3-methylisoxazole: Their Conversion into Silyl-and Methyl Enol Ethers

Acetonitrile oxide reacts regioselectively with 3-buten-2-one and (E)-4-methoxy-3-buten-2-one to give 5-acetyl-2 and 4-acetyl-3-methylisoxazole 3, respectively. Treatment of ketones 2 and 3 with trimethylsilyl trifluoromethanesulfonate gave the silyl enol ethers 4 and 5, whereas the methyl enol ethers 8 and 9 were obtained via elimination of methanol from the corresponding dimethyl ketals.     

Synthesis of 5-Bromomethylisoxazoles and Their Reactions with Secondary Amines

Treating R-3-chloro-4-bromo-2-buten-1-ones with hydroxylamine hydrochloride afforded 3-alkyl(aryl, furyl)-5-bromomethylisoxazoles. By reaction of the latter with secondary amines new previously unknown aminoisoxazoles were synthesized.     

Synthesis and Tuberculostatic Activity of Methyl 3-Isonicotinoyldithiocarbazate and S,S'-Dimethyl Dithiocarbonate Isonicotinoylhydrazone, and Their Reactions with Amines and Hydrazines

Methyl 3-isonicotinoyldithiocarbazates and S,S'-dimethyl dithiocarbonate isonicotinoylhydrazone were prepared. Their reactions with primary and secondary amines, diamines, and hydrazines were studied. The newly obtained derivatives did not show tuberculostatic activity in vitro.     

Synthesis of Indole 2,3-Epoxypropyl Derivatives and Their Reactions with Amines

Indole derivatives with a 2,3-epoxypropyl substituent attached to nitrogen were synthesized. In reactions with primary and secondary amines these compounds afforded the corresponding 1,2-aminoalcohols.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 243–246.Original Russian Text Copyright © 2005 by Suzdalev, Babakova.     

The Methyl Enol Ethers of Ethyl 2, 4-Dioxopentanoate

Methylation of ethyl 2, 4-dioxopentanoate with diazomethane gives a mixture of two enol ethers, the 2-methoxy and the 4-methoxy isomer, with a product ratio which depends upon reaction temperature. Both enol ethers, initially (Z)-configurated, isomerize to the corresponding (E)-conformers, the 4-methoxy compound with particular ease.     

Synthesis of Methyl p-Alkoxyphenylcarbamates and Some Their Reactions

Alkylation of methyl p-hydroxyphenylcarbamate with allyl bromide and 1,4-dibromobutane leads to formation of the corresponding methyl p-alkoxyphenylcarbamates. Reactions of methyl p-allyloxyphenylcarbamate with benzaldehyde, p-methoxybenzaldehyde, p-nitrobenzaldehyde, and p-chlorobenzaldehyde oximes in boiling ethanol in the presence of N-chlorobenzenesulfonamide sodium salt yields 3-aryl-5- (p-methoxycarbonylaminophenoxymethyl)-4,5-dihydroisoxazoles. Methyl p-(4-bromobutoxy)phenylcarbamate reacts with morpholine in benzene to give methyl p-(4-morpholinobutoxy)phenylcarbamate.     

Synthesis of Methyl 4,6-Di-O-ethyl-α-d-glucopyranoside-Based Azacrown Ethers and Their Effects in Asymmetric Reactions

Carbohydrate-based crown ethers have been reported to be able to generate asymmetric induction in certain reactions. Previously, it was proved that the monosaccharide unit, the anomeric substituent, and the sidearm could influence the catalytic activity of the monoaza-15-crown-5 macrocycles derived from sugars. In order to gain information about the effect of the flexibility, 4,6-di-O-ethyl-glucoside-based crown compounds were synthesized, and their efficiency was compared to the 4,6-O-benzylidene analogues. It was found that the absence of the two-ring annulation has a negative effect on the enantioselectivity in liquid-liquid two-phase reactions: in the Darzens condensation of 2-chloroacetophenone and in the epoxidation of chalcone. The same trend was observed in the solid-liquid phase Michael addition of diethyl acetamidomalonate. Surprisingly, in the solid-liquid phase cyclopropanation of benzylidenemalononitrile, one of the new catalysts was highly enantioselective (99% ee).     

Copper Salts Catalysed Addition of Alcohols and Acids to Enol Ethers

Enol ethers have been used for the protection of alcohols (la) and acids (1b,2). The addition of the hydroxyl group on the double bond of the enol ether has been performed, so far, in the presence of a Brönsted acid.     

Synthesis of Silicon-Functionalized Dimethylsilyl Enol Ethers from Ketones

Symmetrical dimethylsilyl bis-enol ethers are obtained in good yield by reaction of ketones with dichlorodimethylsilane in the presence of triethylamine and sodium iodide. Reaction of ketones with N, N - diethylaminodimethylchlorosilane in the presence of triethylamine and sodium iodide followed by subsequent conversions provides a useful synthesis of silicon-functionalized dimethylsilyl enol ethers including unsymmetrical dimethylsilyl bis-enol ethers     

甲基冠醚的合成

将二烯丙基醚(1),乙二醇二烯丙基醚(2)和1,2-丙二醇二烯丙基醚(3)在氯乙醇溶液中汞化-去汞,制得含有甲基侧链的二氯化物(4,5,6),后者与邻苯二酚作用,在KOH存在下,生成相应的甲基冠醚。     

Synthesis and Cationic Polymerization of Open-Chain and Cyclic Enol Ethers

Abstract

Several new open-chain and cyclic enol ether monomers were prepared using simple, straightforward procedures. The reactivities of these monomers were compared using both differential scanning photocalorimetry and Fourier transform real-time infrared spectroscopy. In general, these new monomers were found to possess excellent reactivity in photoinitiated cationic polymerization using a diaryliodonium salt photoinitiator.     

An Efficient Regio and Stereoselective Synthesis of Silyl Enol Ethers

Ketones and aldehydes on treatment with NaBr-Me₃SiCl-Et₃N in DMF at ambient temperature yield silyl enol ethers with high regio- and stereoselecti-vity.     

Synthesis of Diazacrown Ethers with Chromophores and Their Photoinduced Charge‐Separation with Methyl Viologen

Two 4,13‐diaza‐18‐crown‐6 ethers with either two pyrenyl or two carbazolyl groups were synthesized. The two crown ethers can form complexes with methyl viologen in methanol solution. Photoirradiation of the complexes resulted in the electron transfer from the excited states of the chromophores to methyl viologen as demonstrated by the quenching of the chromophore fluorescence and the detection of the absorption spectrum of the generated viologen radical cation. The back electron transfer in these systems was inhibited by the electrostatic repulsion between the positively charged viologen radical cation and the generated chromophore radical cation. Long‐lived charge separation states (up to tens of min) were observed.     

Synthesis of Arylnaphthoquinones and Their Reactions with o‐Substituted Primary Aromatic Amines

Cycloaddition reaction of 2‐aryl‐1,4‐benzoquinones 1a‐d with a number of different dienes, namely 2,3‐dimethylbutadiene; 1,4‐diphenylbutadiene and anthracene yield 2‐aryl‐6,7‐dimethyl‐1,4‐ naphthoquinones 3a,b ; 2,5,8‐triphenyl‐1,4‐naphthoquinone 4 and 2‐aryl‐1,4,9,10‐tetrahydro‐9,10‐o‐benzoanthracene‐1,4‐dione 5 , respectively were investigated. In addition, the cycloaddition reaction of 2‐aryl‐1,4‐benzoquinones 1d,e with 2,3‐dimethylbutadiene was also investigated to yield 2‐aryl‐5,8‐dihydro‐6,7‐dimethyl‐1,4‐naphthohydroquinones 2a,b . Cyclocondensation reactions of Diels‐Alder adducts 2b, 3b, 5a with ethylenediamine, o‐substituted primary aromatic amines gave quinoxaline, phenazine, phenoxazine and phenothiazine ocyclic derivatives 6–14.     

Fluorine-containing Vinyl Ethers: I. Reactions with Carboxylic Acids

Polyfluoroalkyl vinyl ethers take up aliphatic and aromatic carboxylic acids in the presence of 0.2-5 wt% of trifluoroacetic acid at 55-105°C to give fluorine-containing hemiacetals in 60-100% yields.