β,β-Dimethylacrylic acid

A method has been developed for obtaining ,-dimethylacrylic acid from 3-methylbut-3-en-1-ol — a multitonnage product of the production of isoprene by the Prins method.Institute of Organic Chemistry, Academy of Sciences of the Armenian SSR, Erevan. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 313–314, May–June, 1991.     

Synthesis of esters of α-chloroacetoxy-β,β,β,-trichloroethylphosphonic acids

Summary The synthesis of 11 previously unreported dialkyl esters of -mono-, -di-, and -trichloroacetoxy-,,-trichloroethylphosphonic acids has been effected.     

Synthesis and reactivity of alkenyl- and alkynyl-substituted β,β-dihalo-and β,β,β-trichloroamines

β,β-Dihalo- and β,β,β-trichloroamines, obtained by Lewis acid-promoted Petasis-type reaction of α,α-dichlorinated and α,α,α-trichlorinated imines or reduction of α,α-dihaloaldimines, were subjected to a reactivity study and turned out to be remarkably stable compounds. In general, only the bases KO^tBu and NaOMe cause a 1,2-dehydrochlorination with formation of unsaturated α-chloroimines or unsaturated α,α-dichloroimines. Hydrolysis of the α-chloroimines with aqueous oxalic acid resulted in the formation of the corresponding unsaturated α-chloroketones. The reaction of simple β,β-dihaloamines with NaOMe and KO^tBu generated 2-haloprop-2-enylmines and 2,2-dimethoxypropylamines.     

Synthesis of new α,α,β,β-tetrafluoroesters

Substituted phenyl iodides or diiodides reacted with ethyl iodotetrafluoroproponylate ICF₂CF₂CO₂Et, 1 in the presence of copper powder to give the coupled products 2 or 3 in good yields. Addition of 1 to ethylene and allyl acetate proceeded smoothly under thermal and radical conditions to give the corresponding adducts, which underwent elimination reaction to give β-vinyl and β-allyl α,α,β,β-tetrafluoroesters, CH₂CHCF₂CF₂CO₂Et, 4 and CH₂CHCH₂CF₂CF₂CO₂Et, 5, respectively. 1 also readily reacted with 1,5-hexadiene and 1-hexene with copper or palladium complex, followed by reduction to remove iodine to produce ω-alkenyl-α,α,β,β-tetrafluoroester CH₂CH(CH₂)₄CF₂CF₂CO₂Et 6 and α,α,β,β-tetrafluoroester C₄H₉CH₂CHICF₂CF₂CO₂Et.     

Synthesis of β-Fluoroalkyl-β,β-dimethoxy Ketones and β-Fluoroalkyl-β-methoxy-α,β-enones

α-Bromo-β-fluoroalkyl-α,β-enones react with sodium methoxide in methanol to give the corresponding β-fluoroalkyl-β,β-dimethoxy ketones which eliminate methanol molecule to produce a mixture of E/Z-isomeric β-fluoroalkyl-β-methoxyvinyl ketones, the Z isomer prevailing.     

Stereoisomerism ofβ-polyfluoroalkyl-α,β-enones

-Polyfluoroalkyl-,-enones formed in the E,Z form are converted by the action of atmospheric oxygen into a 937 mixture of E,Z and Z,E isomers in the dark and 6040 mixture of these isomers in the light. The Z isomer of 1-phenyl-4,4, 4-trifluoro-2-buten-1-one was isolated preparatively for the first time and its E conformation relative to the C-C bond was established. The Z,E isomer spontaneously transforms into the indicated equilibrium mixtures.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1685–1689, July, 1991.     

β,β-Dinitro derivatives ofN-alkyl-N′-alkoxydiazene-N-oxides

Methods of synthesis ofN-alkyl-N-alkoxydiazene-N-oxides containing a carbonyl group in the -position of alkyl or alkoxy radicals were developed. ,-Dinitro derivatives ofN-alkyl-N-alkoxydiazene-N-oxides were synthesized for the first timevia nitration of oximes obtained from the ketones.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1534–1538, August, 1995.     

Synthesis of 15β, 16β-methyleneprogesterone

15,16-Methyleneprogesterone was produced from 15,16-methylene-3-hydroxyandrost-5-en-17-one with Wittig olefination of 17-ketone by methoxymethylenetriphenylphosphorane as the key stage.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 203–207, January, 1993.     

β,β′-Linked cofacial bis-porphyrins

The copper(II) porphyrin 1, bearing a fused methylenepropano ring, undergoes an unusual self-sensitized photo-oxygenation reaction in the presence of DBU to give a high yield of a cofacial bis-porphyrin 7 under very mild conditions. The structures of compounds 1 and 7 were confirmed by X-ray crystallography.     

Novel Synthesis of 2β,3β,20β-Triacetoxy-5 -pregnan-6-one

Pregnenolone (2) is used in a novel synthesis of 2,3,20-triacetoxy-6-ketosteroid (6), a key intermediate in the preparation of 20-hydroxyecdysone (1)     

An efficient dehyrohalogenation method for the synthesis of α,β,β-trifluorostyrenes, α-chloro-β,β-difluorostyrenes and E-1-arylperfluoroalkenes

Dehydrofluorination of 1-aryl-1,2,2,2-tetrafluoroethanes (ArCHFCF₃) and 1-aryl-1-chloro-2,2,2-trifluoroethane (ArCHClCF₃) using lithiumhexamethyldisilazide (LHMDS) in tetrahydrofuran (THF) at room temperature produced 1,2,2-trifluorostyrene and 1-chloro-2,2-difluorostyrene, respectively, in very good isolated yields. Dehydrofluorination of 1,2,2,3,3,3-hexafluoro-1-phenyl-propane (PhCHFCF₂CF₃) and 1,2,2,3,3,4,4,4-octafluoro-1-phenyl-butane (PhCHFCF₂CF₂CF₃) using LHMDS produced the corresponding substituted olefins (1-phenyl-1,2,3,3,3-pentafluoroprop-1-ene and 1-phenyl-1,2,3,3,4,4,4-pentafluorobut-1-ene) in good yield and high E-selectivity. Dehydrofluorination of 1-chloro-1-phenyl-2,2,3,3,3-pentafluoropropane (PhCHClCF₂CF₃) and 1-chloro-1-phenyl-2,2,3,3,4,4,4-heptafluorobutane (PhCHClCF₂CF₂CF₃) produced a mixture of the corresponding E and Z olefins (PhCClCFCF₃ and PhCClCFCF₂CF₃) in good yield.     

Photochemical addition of diethyl ether to β,β,β',β'-tetrakis(trifluoromethyl)divinyl ether

The 1:1 adducts of diethyl and ,,','-tetrakis(trifluoromethyl)divinyl ether (1),i.e., 3,5-(ee)-bis[2,2,2-trifluoro-1-(trifluoromethyl)ethyl]-2,6-dimethyl-1,4-dioxane (2) (3 isomers) and 4-ethoxy-1,1,1-trifluoro-2-trifluoromethyl-3-[3,3,3-trifluoro-2(trifluoromethyl)propenyloxy]pentane (3), have been obtained by UV-irradiation of a solution of divinyl ether1 in diethyl ether. The X-ray structural investigation of the all-(e)-isomer of dioxane (2) has been carried out.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 85–88, January, 1994.     

聚α,β,β-三氟苯乙烯及其离子交换膜

我所与有关工厂协作研制出一种含氟新材料——聚α,β,β-三氟苯乙烯(以下简称聚三氟苯乙烯)及其阳离子交换膜(SF-1膜),并在高纯烧碱、过氧化氢等的工业生产中进行了初步的应用试验,取得了一定的结果。这里就聚三氟苯乙烯和 SF-1膜的合成、性能和应用情况作扼要的介绍:三氟苯乙烯的合成与聚合三氟苯乙烯的合成方法很多,但大多步骤繁复且收率较低,无制备价值。我们经过探索找到了由格氏试剂与四氟乙烯反应一步制取三氟苯乙烯的方法。C_6H_5MgCl+CF_2(?)CF_2→CF_2=CFC_6H_5+MgClF反应以氯苯为原料,以四氢呋喃为溶剂,纯单体收     

Synthesis of bis-β,β′-spiro-pyrrolidinyl-oxindoles,containing a rhodanine fragment

The synthesis of isatilidene derivatives of N-alkylrhodanines has been carried out with dipolarophiles and unstable azomethine ylides, generated in situ from sarcosine and paraformaldehyde. A series of chiral pyrrolidinyl-oxindoles spirofused in the β,β′-positions has been synthesized in the result of cycloaddition in high yield and diastereoselectivity.     

5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇的合成

以5-雄烯二醇为原料,用微生物转化的方法合成了两个重要的神经甾体5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇。所用菌种总枝毛霉为我们自己筛选,并首次应用于5-雄烯-3β, 7α, 17β-三醇和5-雄烯-3β, 7β, 17β-三醇的合成中。     

Nitroderivate vonβ,β,β-Trihalo-α,α-bis-(4-alkoxybzw. 4-oxy-phenyl)-äthanen

Zusammenfassung Auf Grund von Modellbetrachtungen wurde die Existenz der in der Literatur beschriebenenOctanitro-Derivate von ,,-Trihalo-,-bis-(4-alkoxy-phenyl)-äthanen in Zweifel gezogen. Entsprechende Untersuchungen ergaben, daß es sich bei ihnen umTetranitro-Verbindungen handelt und daß es nicht möglich ist, diese DDT-Analogen mehr als vierfach zu nitrieren. Die Konstitution der Tetranitro-Verbindungen wurde durch Abbau bewiesen: Beim ,,-Trichlor-,-bis-(3,5-dinitro-4-methoxy-phenyl)-äthan (II) durch Überführung in das entsprechende Keton (VII), beim ,,-Trichlor-,-bis-(3,5-dinitro-4-äthoxy-phenyl)-äthan (IV) durch Entalkylierung und Methylierung zu II. Der Beweis der 3,3, 5,5-Stellung der Nitrogruppen in II und IV ist auch für andere Tetranitro-Derivate von ,,-Trihalo-,-bis-(4-X-phenyl)-äthanen (X=Substituenten I. Ordnung) von Bedeutung.Mitt. II der Reihe: Stereochemische Untersuchungen in der Diphenylmethanreihe.     

β,β-Difluoro analogs of α-oxo-β-phenylpropionic acid and phenylalanine

A simple three-step procedure converted the readily accessible (2-bromo-1,1-difluoroethyl)arenes (2) into α-aryl-α,α-difluoroacetaldehydes (1). Subsequent hydrocyanation, hydrolysis, oxidation and again hydrolysis afforded β-aryl-β,β-difluoro-α-oxopropionic acids (3). Reductive amination transformed the oxoacids 3 into a separable mixture of α-hydroxyacids 11 and racemic β,β-difluoro-β-phenylalanine derivatives (4). Enantiomerically pure β,β-difluorophenylalanine (l-4a) was obtained when α,α-difluoro-α-phenylacet-aldehyde (1a) was condensed with homochiral 1-phenylethylamine, hydrogen cyanide added to the resulting imine, the diastereomeric mixture thus produced hydrolyzed to the carboxamides (15) which were found to be separable by fractional crystallization or chromatography. The pK_a values of the β-aryl-β,β-difluoroalanines (4) were measured and biological profile of the latter probed. 3-(4-Chlorophenyl)-3,3-difluoro-2-oxopropionic acid (4c) proved to be a potent (K_i 27 μM) and selective inhibitor of arogenate dehydratase, a key enzyme catalyzing the last step of the phenylalanine biosynthesis.