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.     

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.     

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.     

镍催化α,β-不饱和醛的选择性α,β-双芳基化反应

三组分双官能化反应是一种高效、简便构建C―C键、C―X键的方式.双键广泛存在于众多有机化合物中,对双键的双官能化反应研究有巨大的应用潜力.本工作以Ni(COD)2为催化剂,以芳基溴化镁、芳基溴化物为芳基化试剂,实现了3-芳基-2-丙烯醛亚胺中碳碳双键的双芳基化反应.该反应建立了一个新的镍催化α,β-不饱和醛的α,β-双芳基化方法,可以高度区域选择性地向底物分子中引入两个不同取代的芳环,得到多种2,3,3-三芳基丙醛骨架的产物.利用这一反应作为核心步骤实现了天然产物Quebecol的简便合成.机理研究表明,该反应可能经历了亲核加成、金属交换、还原消除的历程.     

Reaction of 5β,6β-epoxy-16α,17α-cyclohexapregnane with methylmagnesium iodide

On treatment with methylmagnesium iodide, 3β-acetoxy-5β,6β-epoxy-16α,17α-cyclo-hexapregnan-20-one undergoes 3-O-deacetylation along with the opening of the 5β,6β-epoxide ring to form 5α-methyl-6β-hydroxy steroid and the 6α-methyl-6β-hydroxy isomer, the 20-keto group remaining intact.     

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     

Crystal Structure of 6β,7β,14β-Trihydroxy-1α-acetoxy-7α,20-epoxy-ent-kaur-16-en-15-one

6β,7β,14β-Trihydroxy-1α-acetoxy-7α,20-epoxy-ent-kaur-16-en-15-one was isolated from the natural plant of Isodon japonica (Burm.f), Haravar. galaucocalyx (maxim) Hara. The structure was elucidated by means of spectral and chemical studies. In addition, its crystal was determined by single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P1, Z = 2, a = 6.3506(4), b = 13.5766(8), c = 15.2777(9) , α = 80.506(1), β = 83.856(1), γ = 88.307(1)o, C25H36O9, Mr = 480.54, V = 1291.64(13) 3, Z = 2, Dc = 1.236 g/cm3, F(000) = 516, μ = 0.093 mm-1, S = 0.988, the final R = 0.0761 and wR = 0.1955. Flack factor is 0.02(19), and the largest peak and deepest hole on the final difference Fourier map are 0.556 and –0.265 e/3, respectively. The X-ray diffraction shows the existence of intermolecular C–H…O (DA) hydrogen bonds between adjacent molecules.     

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.     

Über die Darstellung von 3β, 16α-und 3β, 16β-Diacetoxy-5α-pregnan-20-on

Zusammenfassung Die Synthese von 3, 16-Diacetoxy-5 -pregnan-20-on (VI) aus 3-Acetoxy-5 -pregn-16-en-20-on und eine verbesserte Darstellung von 3, 16-Diacetoxy-5 -pregnan-20-on (III) aus 3-Acetoxy-pregna-5, 16-dien-20-on werden beschrieben.     

α,β-不饱和醛及其合成

α,β-不饱和醛因其浓郁的香味、特殊的结构及很多有意义的化学反应,引起了化学家们极大的兴趣,它在配制香料及有机合成中的应     

A convenient synthesis of α',β-diamino-α,α-difluoroketones,new dipeptide isosteres

A convenient and versatile synthesis of α′,β-diamino-α,α-difluoroketones is described. These compounds represent a new class of true isosteres useful for the design of serine protease inhibitors.     

Possible conformations of the seven-membered rings and relative stabilities of 1β,5α,6β,7α(H)- and 1α,5α,6β,7α(H)-guai-11(13)-en-6,12-olides

A calculation has been made by the method of molecular mechanics, using the MM2 program, of a number of stereomeres of 1,5,6,7(H)- and 1,5,6,7(H)-guai-11(13)-en-6,12-olides. The possibilities of the adoption by the seven-membered ring of particular conformations according to the type of its linkage with the 5-membered carbocycle have been considered. Questions of the influence of the orientation of the Me groups on the degree of distortion of the conformation of the seven-membered ring from the ideal and the relative stabilities of the various conformers are discussed.A. N. Nesmeyanov Institute of Organometallic Compounds, Academy of Sciences of the USSR, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 198–203, March–April, 1991.     

Conformation and chiral effects in α,β,α-tripeptides

Short α,β,α-tripeptides comprising a central chiral trisubstituted β(2,2,3)*-amino acid residue form unusual γ-turns and δ-turns in CDCl(3) and DMSO-d(6) solutions but do not form β-turns. Thermal coefficients of backbone amide protons, 2D-NMR spectra, and molecular modeling revealed that these motifs were strongly dependent on the configuration (chiral effect) of the central β-amino acid residue within the triad. Accordingly, SSS tripeptides adopted an intraresidual γ-turn like (C6) arrangement in the central β-amino acid, whereas SRS diastereomers preferred an extended δ-turn (C9) conformation. A different SRS-stabilizing bias was observed in the crystal structures of the same compounds, which shared the extended δ-turn (C9) found in solution, but incorporated an additional extended β-turn (C11) to form an overlapped double turn motif.     

Synthesis of 5α, 13α, 14α-Androstan-16-One and 5α, 13β, 14β—Androstan-16-One Using a Novel 17–16 Carbonyl Transposition

In the course of current work on the conformational analysis of cis-hydrindanones¹, we required 5α, 13α, 14α and 5α, 13β, 14β-androstan-16-one 5 and 10 the C and D rings of which provide rigid models of the two conformations of cis-hydrindan-2-one.     

α,β-不饱和酰胺的合成研究进展

α,β-不饱和酰胺是有机合成中的重要基团,存在于某些蛋白质以及高分子化合物的骨架结构中,因其可以与特定蛋白质的独特半胱氨酸残基发生不可逆的异-迈克尔加成反应共价结合细胞靶标,被广泛应用于药物合成中,使得此类化合物的合成成为药物化学的研究热点。本文从铜、钯、钴、镍等过渡金属催化以及无过渡金属合成等方面进行介绍,对近年来α,β-不饱和酰胺基团的合成方法进行总结与评述,并对部分反应机理进行了阐述。     

Diastereoselective synthesis of diketopiperazine bis-α,β-epoxides

Functionalized diketopiperazines (dioxopiperazines) are an important class of molecules in medicinal chemistry and material science. Herein we report a diastereoselective synthesis of diketopiperazine bis-α,β-epoxides via the oxidation of exocyclic olefins. Although six diastereomers may be formed by this approach, only one or two of them were observed.     

α,β-不饱和内酯的光化学反应研究进展

α,β-不饱和内酯的光化学反应可广泛应用于核苷、稠环生物碱、萜类、甾类等多种光学活性物质与天然产物的合成中.根据不同的反应类型,综述了2(5H)-呋喃酮等α,β-不饱和内酯的光化学1,4-加成反应、1,4-加成-并环反应、[2+2]环加成反应和复杂环加成反应的新进展.