A Convenient and Efficient Procedure for Oxime Ethers

In connection with our asymmetric reduction research, we are of interest to synthesize ketoxime ethers because they give good enantioselectivty in the reduction system of Lewis acid-NaBH4-Ligand1. In the literature the oxime ethers were made under anhydrous conditions using strong base such as NaH or sodium alkoxides to realize the substitution reaction between alkyl halide and oxime2. The reaction has also been performed under PTC conditions3. There were cases where the yields were low…     

Synthesis of trifluoroethyl ethers from 2,2,2-trifluoroethyl chloride (HCFC-133a) in high temperature aqueous medium

Treatment of 2,2,2-trifluoroethyl chloride (HCFC-133a) with alcohols (phenols) and aqueous KOH in autoclave at 240-280 °C gives the corresponding 2,2,2-trifluoroethyl (2-chloro-1,1-difluoroethyl) ethers in good yields.     

Vinylation of hydroxy-containing cyclic formaldehyde acetals with acetylene

Nucleophilic addition of alcohols having cyclic acetal fragments to acetylene smoothly occurs under relatively mild conditions (KOH, 100–125°C, 1–2 h, initial acetylene pressure 11–12 atm) to give the corresponding vinyl ethers in 80–83% yield.     

Tuneable superbase-catalyzed vinylation of α-hydroxyalkylferrocenes with alkynes

Superbase-catalyzed (KOH/DMSO suspension as a catalyst) vinylation of hydroxymethyl- and hydroxyethylferrocenes with terminal and internal alkynes (acetylene, propyne, phenylacetylene, 3-ethynylpyridine, 1-propyn-1-yl-benzene, diphenylacetylene) affords hitherto unknown vinyl ethers of ferrocene in 30–93% yields depending on the alkyne structure and the tuneable ratio of reactants/KOH/DMSO. The vinylation smoothly proceeds under mild conditions (70–90 °C, 0.25–13 h). With unsubstituted acetylene the process is readily realized under atmospheric pressure (yield of the corresponding vinyl ethers is 81–90%) though under pressure (initial pressure at room temperature is 10–13 atm, maximum pressure is 13–16 atm at the reaction temperature) the yield is close to quantitative (93%). The synthesized compounds were characterized using ¹H and ¹³C NMR, and IR spectroscopy, as well as X-ray diffraction analysis.     

Halogenation of propargyl ethers of heterylaldoximes and ketoximes under interphase catalysis conditions

The halogenation of propargyl ethers of heterylaldoximes and ketoximes in interphase catalytic systems CX₄ (X=Cl, Br)/solid KOH/18-crown-6 leads selectively to the formation of the corresponding O-(halopropargyl)oximes. Latvian Institute of Organic Synthesis, Riga LV-1006. e-mail: kira@osi.lanet.lv. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1325–1328.     

Nucleophilic Addition to Acetylenes in Superbasic Catalytic Systems: XIV. Vinilation of Diols in a System CsF-NaOH

A new catalytic system CsF-NaOH was developed for the synthesis of mono- and divinyl ethers of alkanediols exceeding in efficiency KOH. The nucleophilic addition of diols to acetylene in the presence of this system occurs both at enhance pressure (without solvent, 140–160°C) and atmospheric pressure (in DMSO medium, 100°C) of acetylene. Conditions were established of a selective preparation in a high yield of divinyl ethers from diols.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 677–683.Original Russian Text Copyright © 2005 by Oparina, Khil’ko, Chernyshova, Shaikhudinova, Parshina, Preiss, Henkelmann, Trofimov.     

Synthesis of Isomeric Dinitro and Diamino Derivatives of Polycyclic Crown Ethers: Dibenzo-18-crown-6 and Dibenzo-24-crown-8

Specific features of the synthesis of polycyclic crown ethers dibenzo-18-crown-6 and dibenzo-24-crown-8 and their dinitro and diamino derivatives have been studied. A mixture of isomers of dibenzocrown ether derivatives was obtained and separated. The spectral and thermal characteristics of the synthesized compounds and the kinetics of synthesis of dibenzo-24-crown-8 by the two-component condensation of pyrocatechol with 1-chloro-2-[2-(2-chloroethoxy)ethoxy]ethane in an alcoholic medium in the presence of a KOH template agent were studied.     

Crown Ether Phase Transfer Catalysts for An Ionic Polymerization of Bisphenol A / 4,4′‐Dichlorodiphenyl Sulfone

Various crown ethers were prepared and applied as phase transfer catalysts for the an ionic copolymerization of bisphenol A and 4,4′‐dichlorodiphenyl sulfone monomers with alkali salts, e.g., NaNH₂, NaOH and KOH, as initiators. The catalytic abilities of various crown ethers for the an ionic polymerization of bisphenol A / 4,4′‐dichlorodiphenyl sulfone were found to be in the order: 15‐crown‐5 ? monobenzo‐15‐crown‐5 > 18‐crown‐6 > Dicyclohexano‐18‐crown‐6 > Dibenzo‐18‐crown‐6 > 12‐crown‐4 with sodium amide (NaNH₂) as initiator. Sodium amide was shown to be a better initiator than NaOH or KOH with monobenzo‐ 15‐crown‐5 as a catalyst. Effects of solvents and temperature on the crown ether catalytic polymerization were also investigated. Dimethyl sulfoxide (DMSO) exhibited much better for the polymerization than other organic solvents, e.g., toluene, p‐xylene, dimethyl formamide and dioxane. Higher polymerization was found at higher temperatures and about 100% yield of poly(bisphenol A / sulfone) was obtained at 125 °C in 3 hr. The molecular weight of poly(bisphenol A / sulfone) as a function of reaction time was determined with gel permeation chromatography. Concentration effects of crown ether on % yield and molecular weight of poly(bisphenol A / sulfone) were also investigated and discussed.     

C(10)-C(19) bond cleavage reaction of 19-oxygenated androst-4-ene-3,6-dione steroids under various conditions

C(10)-C(19) bond cleavage reaction of 19-hydroxy- and 19-oxoandrost-4-ene-3,6,17-triones (5, 6) was explored under various conditions. Treatment of steroids 5 and 6 with KOH in MeOH gave the A-ring aromatized product 6-oxoestrone (11) in a fair yield, respectively, in contrast, the treatment with a weak base yielded 4-methyl steroid 17 (20%) in the case of 19-alcohol 5 or 19-nor-Delta(5(10))-steroid 9 (12-67%) along with compound 11 (6-27%) in the case of 19-aldehyde 6. Reaction of compound 6 with HCl in MeOH produced 3-methyl ethers of 6-oxoestrone and Delta(6)-estrone, compounds 12 and 14 (ca. 20% each). Thus, 6-oxosteroids 5 and 6 showed unique C(10)-C(19) bond cleavage reactions with a base or acid.     

Synthesis of alkyl heteryl ethers from acetates under interphase catalysis conditions in a liquid/solid system

The reaction of acetates of heterocyclic alcohols with alkyl halides in the two-phase catalytic system of solid KOH/C₆H₆/18-crown-6 at room temperature leads selectively to the formation of the corresponding heterocyclic ethers in 32–93% yield.Latvian Institute of Organic Synthesis, Riga LV-1006, e-mail: kira@osi.lanet.lv. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 46–49, January, 1998.     

The selective reaction of aryl halides with KOH: synthesis of phenols, aromatic ethers, and benzofurans

The direct and selective synthesis of phenols from aryl/heteroaryl halides and KOH has been achieved through the use of highly active monophosphine-based catalysts derived from Pd(2)dba(3) and ligands L1 or L2 and the biphasic solvent system 1,4-dioxane/H(2)O. We have also demonstrated a one-pot method of phenol formation/alkylation for the preparation of alkyl aryl ethers from aryl halides. In many instances, this protocol overcomes limitations in existing Pd-catalyzed coupling reactions of aliphatic alcohols with aryl halides. Finally, we demonstrate that substituted benzofurans can be prepared efficiently via a Pd-catalyzed phenol formation/cyclization protocol starting from 2-chloroaryl alkynes.     

Reaction of perfluoro-2-methyl-2-pentene with cycloalkanone oximes: new examples of the Beckmann—Chapman rearrangement

The base-catalyzed reaction of cycloalkanone oximes (la,b) with perfluoro-2-methyl-2-pentene (PFMP) initially affords the addition products,i.e., fluoroalkyl ethers (2a,b). In the presence of KOH, the latter undergoes dehydrofluorination to give perfluoroalkenyl ethers (3a,b). Thermolysis of ethers3a,b results in compounds of two types — pyrrolines (4a,b) andN-perfluoroalkenyl lactams (5a,b). The latter are also prepared from PFMP and the corresponding lactams. The structure ofN-[perfluoro-(2-methyl-2-penten-3-yl)]-2-pyrrolidone (5c) was established by X-ray diffraction study.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1073–1077, June, 1994.     

Base promoted isomerization of aziridinyl ethers: a new access to alpha- and beta-amino acids

Aziridinyl ethers are selectively and easily converted to either amino vinyl ethers or alkoxy allylamines by treatment with mixed metal bases (superbases).     

Reaction of HCFC‐133a (CF3CH2C1) or HFC‐134a (CF3CH2F) with alcohols or phenols in DMSO in the presence of KOH

In an open glassware, heating a gas HCFC‐133a (CF₃CH₂C1) or HFC‐134a (CF₃CH₂F), KOH and a phenol (or an alcohol) in DMSO at 80°C gave ethers ROCF₂CH₂X and (E/Z)‐ROCF = CHX (X = Cl, F) in moderate yields.     

Glycosylated vinyl ethers by the Julia–Lythgoe–Kocienski olefination: application to the synthesis of 2′,5′-dideoxydisaccharides and carbohydrated β-lactams

α-Carbohydrated pyridinyl sulfones, prepared from commercially available d-(−)-ribose, d-(+)-galactose, and d-(+)-glucose through a five-step sequence, have been employed in the Julia–Lythgoe–Kocienski olefination with aldehydes. This one-pot protocol, using solid KOH at room temperature, affords the corresponding glycosidic enol ethers in moderate to excellent yields and (E)-stereoselectivities. These glycosylated adducts undergo hetero-Diels–Alder reactions with 2-formyl-1-malondialdehyde to afford 2′,5′-dideoxygenated disaccharides in good yields and complete regio- and endo-selectivity. Alternatively, the [2+2]-cycloaddition reaction of the glycosidic enol ethers with chlorosulfonyl isocyanate provided glycosylated β-lactams regioselectively and with only trans-stereoselectivity. The β-lactams could be converted to N-methylthio derivatives which show decent antibacterial activity toward methicillin-resistant strains of Staphylococcus aureus.     

Isomerization and Cleavage of Allyl Ethers of Carbohydrates by Trans- [Pd(NH3)2Cl2

Allyl ethers are widely used for the “temporary” protection of hydroxy groups in carbohydrates. The allyl group is conveniently removed by isomerization and subsequent cleavage of the labile prop-1-enyl group.² The rearrangement of allyl ethers to prop-1-enyl ethers is readily achieved by treatment with potassium t-butoxide in dimethyl sulfoxide, using tris(tripheny1phosphine)rhodium chloride, palladium on activated charcoal and by an ene reaction with diethylazodicarboxylate. acidic conditions, ozonolysis followed by alkaline hydrolysis, reaction with alkaline permanganate solution, or treatment with mercuric chloride in the presence of mercuric oxide. The isomerization of allyl ethers to prop-1-enyl ethers can also be carried out in the presence of palladium on carbon or complex bis(benzonitrile)palladium(11) chloride. Bruce and Roshan-Ali' showed that derivatives of allyl phenyl ether are smoothly cleaved by this complex. This has made it possible to remove the protecting group in a one-pot operation. We have now investigated the effect of palladium catalysts on the isomerization and cleavage of the allyl group in carbohydrate derivatives.     

Changes in the Inter- and Intra- Fibrillar Structure of Lyocell (TENCEL®) Fibers after KOH Treatment

Lyocell fibers were treated with KOH up to 8 M which was demonstrated to distribute homogeneously at the outer zones of fiber cross section compared to NaOH which accesses more deeply but less homogenously. Both NaOH and KOH solutions can be used to lower significantly the fibrillation of lyocell fibers. However, due to intrafibrillar swelling together with deep penetration ability of alkali seen for NaOH treatments results in great fiber tensile strength loss which is not observed for KOH treatments due to its inability to penetrate the fiber completely. The porous structure of fibers was studied by inverse size exclusion chromatography (ISEC) to identify mean pore diameter, total pore area and accessible pore volume (APV). Mean pore diameter of fibers decreased after KOH treatments which did not change after NaOH treatments. Wide angle X-ray diffraction analyses (WAXD) were applied to identify the crystallinity index and crystallite size. In general, fiber properties such as water retention value, carboxyl content using methylene blue sorption method, depth of color measured after dyeing with C.I. Direct Red 81 and weight loss were distinctly different in the ranges up to 2 M, 2-5 M and 5 to 8 M KOH. KOH treatment suggests new possibilities for the pretreatment of lyocell fibers to lower fibrillation while slightly lowering elongation at break without a distinct loss in tensile strength and with less decrease in carboxyl content and weight loss without changing dyeing properties of fibers compared to NaOH treatment.     

Silicon in synthesis: The use of trimethylsilyl cyanide for the synthesis of aliphatic cyanomethylethers

The conversion of aliphatic alcohols into cyanomethyl ethers $\text{via}$ treatment of methyl sulfoxymethyl ethers with trimethylsilyl cyanide - zinc iodide is described.     

贮氢合金电极的活化方法和作用机理研究

比较研究了采用电化学方法、ＫＢＨ４还原，ＫＯＨ刻蚀及ＫＯＨ＋ＫＢＨ４联合作用对Ｍｍ（ＮｉＣｏＭｎＡｌ）５型贮氢电极的活化作用，发现采用浓热ＫＯＨ处理的电极可以实现快速充分的活化，且具有放电电压低、稳定容量高及操作简便的特点．对活化过程的作用机理研究表明，ＫＯＨ活化主要是通过溶解反应使稀土和镍元素富集生成有利于吸氢反应的表面组成．ＫＢＨ４及电化学活化方法则是利用反应产生的活性氢裂解合金颗粒，生成高活性的新鲜表面和晶体缺陷     

N-Iodosuccinimide (NIS) as a mild and highly chemoselective catalyst for deprotection of tert-butyldimethylsilyl ethers

A variety of alcoholic TBDMS (t-butyldimethylsilyl) ethers are easily removed in excellent yields by treatment with a catalytic amount of N-iodosuccinimide (NIS, 5 mol %) in methanol. This method is able to deprotect TBDMS ethers of alcohols in the presence of TBDMS ethers of phenols.