- The fluid-mosaic model, homeoviscous adaptation, and ionic liquids: Dramatic lowering of the melting point by side-chain unsaturation
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(Figure Presented) Defying conventional wisdom: Ionic liquids (ILs) with long, unsaturated alkyl appendages (see top structure) defy established trends that link long ion-bound alkyl groups to higher melting points. The new ILs are also less viscous than a saturated standard (see bottom structure) at the same temperature. These features parallel those that underpin homeoviscous adaptation in certain organisms and are indirectly supportive of a fluid-mosaiclike nanoscale character.
- Murray, Samuel M.,O'Brien, Richard A.,Mattson, Kaila M.,Ceccarelli, Christopher,Sykora, Richard E.,West, Kevin N.,Davis Jr., James H.
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Read Online
- Phase-Transfer Nucleophilic Reactions Using Water-Insoluble Alcohols as Organic Solvents
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Simple nucleophilic substitutions were done under liquid-liquid phase-transfer reaction conditions using water-insoluble alcohols as organic solvents.The reactions proceeded at considerable rates even in the absence of any catalysts, depending on the alcohol, inorganic salt, and the aqueous concentration of the salts.An addition of single- or double-chained onium salts enhanced the reaction rate almost linearly with the amount of the onium salts.The concentrations of inorganic salts and water in the alcohol phase were analyzed and the relationship between these concentrations and the observed rate constant was discussed.An interfacial reaction mechanism explains the kinetics of this reaction system better than the conventional ion-pair mechanism assumed by most research using hydrocarbon solvents.
- Ohtani, Noritaka,Inoue, Yukihiko,Shinoki, Noriyuki,Nakayama, Katsuhiro
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Read Online
- Catalytic Iodination of the Aliphatic C-F Bond by YbI3(THF)3: Mechanistic Insight and Synthetic Utility
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A facile iodination protocol of unactivated alkyl fluorides using catalytic amounts of YbI3(THF)3 in the presence of iodotrimethylsilane as a stoichiometric fluoride trapping agent is presented. 1H NMR spectroscopy demonstrates a two-step catalytic cycle where TMSI regenerates active YbI3(THF)3. Finally, the catalytic reaction is extended into a one-pot procedure to demonstrate a potential application of the method. Overall, the findings present a distinct strategy for C-F bond transformations in the presence of catalytic YbI3(THF)3.
- Janjetovic, Mario,Ekebergh, Andreas,Tr?ff, Annika M.,Hilmersson, G?ran
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supporting information
p. 2804 - 2807
(2016/07/06)
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- A practical in situ generation of the schwartz reagent. reduction of tertiary amides to aldehydes and hydrozirconation
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A new, highly efficient in situ protocol (Cp2ZrCl2/LiAlH(OBu-t)3) is described for the generation of the Schwartz reagent which provides a convenient method for the amide to aldehyde reduction and the regioselective hydrozirconation-iodination of alkynes and alkenes. Highlighted are chemoselective reductions of benzamides derived by directed ortho metalation (DoM) chemistry, allowing the synthesis of valuable 1,2,3-substituted benzaldehydes. The single-step, three-component process proceeds in a very short reaction time, shows excellent functional group compatibility, and uses inexpensive and long-storage stable reducing reagents.
- Zhao, Yigang,Snieckus, Victor
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supporting information
p. 390 - 393
(2014/04/03)
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- Asymmetric total synthesis of all four isomers of 6-acetoxy-5- hexadecanolide: The major component of mosquito oviposition attractant pheromones
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An asymmetric total synthesis of (5S,6R)-(+)-erythro-6-acetoxy-5- hexadecanolide 1a has been accomplished from readily available hex-5-yn-1-ol via Shi's asymmetric epoxidation as the key step, in eight steps with an overall yield of 33.5%. In addition, the stereoselective synthesis of all four isomers of 6-acetoxy-5-hexadecanolide 1a-1d were obtained via Sharpless asymmetric dihydroxylation and Mitsunobu reaction as the key steps with overall yields of 16.5-21.2%, respectively.
- Dong, Hong-Bo,Yang, Ming-Yan,Zhang, Xiao-Teng,Wang, Ming-An
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p. 610 - 616
(2014/05/20)
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- Selective C-F bond activation: Substitution of unactivated alkyl fluorides using YbI3
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F makes the break: The carbon-fluorine single bond is quite strong, thus making aliphatic C-F bond scission unusually challenging. A new methodology utilizing YbI3 leads to the conversion of a C-F bond into a C-I bond, and is compatible with various functional groups. The reaction is exceptionally selective towards alkyl fluorides and proceeds under mild conditions. Copyright
- Traeff, Annika M.,Janjetovic, Mario,Ta, Linda,Hilmersson, Goeran
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supporting information
p. 12073 - 12076
(2013/12/04)
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- Ionic liquids as reagents and solvents in conjunction with microwave heating: Rapid synthesis of alkyl halides from alcohols and nitriles from aryl halides
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We show that using ionic liquids as reagents in conjunction with microwave heating it is possible to prepare primary alkyl halides from the corresponding alcohols rapidly. Using ionic liquids as solvents in conjunction with microwave heating it is possible to prepare aryl nitriles from the corresponding aryl bromides or iodides. The scope and limitations of using microwave-promotion as a tool in these reactions is discussed.
- Leadbeater, Nicholas E.,Torenius, Hanna M.,Tye, Heather
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p. 2253 - 2258
(2007/10/03)
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- A novel hydrogen transfer hydroalumination of alkenes with triisobutylaluminum catalyzed by Pd and other late transition metal complexes
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Hydrogen transfer hydroalumination of terminal alkenes and dienes can be achieved with 1.1 equiv. of (i-Bu)3Al and catalytic amounts of Cl2Pd(PPh3)2 and other late transition metal complexes containing Co, Rh, Ni, and Pt at ambient temperature in high yields.
- Gagneur, Sebastien,Makabe, Hidefumi,Negishi, Ei-Ichi
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p. 785 - 787
(2007/10/03)
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- Thiocyanation of alkyl halides with alkyl thiocyanates in the presence of quaternary phosphonium halides
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Alkyl thiocyanates undergo simple SN2 reactions with the counter ions of quaternary phosphonium salts in nonpolar solvents and thiocyanate ions are liberated as the leaving ion. Depending on the nucleophile, the reaction proceeded irreversibly or reversibly. The reaction of benzyl thiocyanate with azide ions afforded a quantitative yield of benzyl azide. The reactions of alkyl thiocyanates with halide ions gave an equilibrium mixture where the reverse reaction of the alkyl halides produced with the liberated thiocyanate ions took place simultaneously. Thus, thiocyanate-halide exchange reactions between an alkyl thiocyanate and an alkyl halide were possible in the presence of a catalytic amount of a quaternary salt.
- Ohtani, Noritaka,Murakawa, Shigeki,Watanabe, Kohji,Tsuchimoto, Daisuke,Sato, Daiki
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p. 1851 - 1856
(2007/10/03)
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- Hydrogen transfer hydrozirconation of alkenes with iBuZrCp2Cl catalyzed by Lewis-acidic metal compounds containing Al, Zn, Si, Ag, and Pd
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The hydrozirconation reaction of monosubstituted alkenes with iBuZrCp2Cl can be significantly accelerated by catalytic amounts of various Lewis acidic metal compounds, most notably AlCl3, Me3SiI, and Pd complexes, such as Li2PdCl4 and Cl2Pd(PPh3)2.
- Makabe, Hidefumi,Negishi, Ei-Ichi
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p. 969 - 971
(2007/10/03)
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- Preparation of Biologically Active Hydroxyketones and Analogues system through Masked Lithium ω-Enolates Generated by a Naphthalene-catalyzed lithiation
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The reaction of ω-chloroacetal 1 with lithium and a catalytic amount of naphthalene (4 molpercent) in THF at -78 deg C leads to intermediate 3, which by reaction with different electrophiles tCHO, PhCHO, Et2CO, (CH2)5CO, CH3(CH2)nCON(OMe)Me (n = 5, 6)> and final hydrolysis with water affords functionalized acetals 2.Acidic treatment of compounds 2 provides functionalized aldehydes 4.Titanium (IV) mediated chemoselective addition of n-butyllithium to ketoaldehydes 4f,g affords after hydrolysis, hydroksyketones 5f, g.Naphthalene-catalyzed lithiation of chloroacetal 6 followed by reaction with n-butanal yields, after hydrolysis, hydroxyacetal 7, which after transformation into the THP-protected dithiane 9 gives hydroxyketone 10, after successive deprotonation, alkylation and final full deprotection.Hydroxyketones 5g and 10 are interesting natural products. - Key words: hydroxyketones; lithiation; naphthalene; natural products
- Alonso, Emma,Ramon, Diego J.,Yus, Miguel
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- The versatile behavior of the PdCl2/Et3SiH system. Conversion of alcohols to the corresponding halides and alkanes
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The versatility of the palladium(II) chloride/triethylsilane system has been tested in the transformation of alcohols. The conversion to the corresponding halides and alkanes has been achieved in good yields and in the absence of solvent for a variety of substrates.
- Ferreri,Costantino,Chatgilialoglu,Boukherroub,Manuel
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p. 135 - 137
(2007/10/03)
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- Diiodosilane. 2. A Multipurpose Reagent for Hydrolysis and Reductive Iodination of Ketals, Acetals, Ketones, and Aldehydes
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The reaction patterns of diiodosilane (SiH2I2, DIS) with ketals, acetals, ketones, and aldehydes were explored.The reagent may be used for mild cleavage of ketals and acetals either hydrolytically to give the parent carbonyl functionality or reductively to produce the corresponding alkyl iodide.At low temperatures (-42 deg C) and short reaction times (few minutes), catalytic amounts (5-10 molpercent) of DIS provide clean deprotection of various ketals and acetals to yield ketones and aldehydes, with no apparent reduction of the latter.At temperatures above 0 deg C, DIS effectively reduces ketals and acetals to iodoalkanes.This reduction is quite general both with respect to ketals and acetals and unprotected ketones and aldehydes.Reaction rates, however, are strikingly dependent on the substrate, with the following tendencies: (a) aromatic functionalities are generally reduced much faster than their aliphatic analogues; (b) ketals and acetals are rapidly reduced to the corresponding iodoalkanes, while free aldehydes, and particularly ketones, are essentially inert under the reaction conditions (but can be significantly activated by catalytic amounts of iodine); (c) dimethyl ketals form the parent ketones preferentially, while all other ketals, including diethyl ketals and dioxolanes, are reduced to iodoalkanes.
- Keinan, E.,Perez, D.,Sahai, M.,Shvily, R.
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p. 2927 - 2938
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS.9. RAPID REACTION OF ORGANOBORANES WITH IODINE UNDER THE INFLUENCE OF BASE. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO IODIDES VIA HYDROBORATION
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The reaction of organoborane with iodine is strongly accelerated by sodium hydroxide.Organoboranes derived from terminal alkenes react with the utilization of approximately two of the three alkyl groups attached to boron, providing a maximum of 67percent yield of alkyl iodide.Thus, hydroboration-iodination of 1-decene gives a 60percent yield of n-decyl iodide.Secondary alkyl groups, derived from internal alkenes, react more sluggishly and only one of the three alkyl groups attached to boron is converted to the iodide.Thus, the procedure applied to 2-butene provides a 30percent yield of 2-butyl iodide.The use of disiamylborane bis-(3-methyl-2-butylborane, Sia2BH as hydroborating agent increases the yield of iodides from terminal alkenes since the primary alkyl groups react in preference to the secondary siamyl groups.Consequently, hydroboration of 1-decene with Sia2BH, followed by iodination gives a 95percent yield of n-decyl iodide.The use of methanolic sodium methoxide in place of sodium hydroxide provides alkyl iodides in considerably higher yields.The combination of hydroboration with iodination in the presence of a base provides a convenient method for the anti-Markovnikov hydroiodination of alkenes.The base-induced iodination of organoboranes proceeds with the inversion of configuration at the reaction center, as shown by the formation of endo-2-iodonorbornane from tri-exo-norbornylborane.
- Brown, Herbert C.,Rathke, Michael W.,Rogic, Milorad M.,de Lue, Norman R.
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p. 2751 - 2762
(2007/10/02)
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- The Use of Silica Gel-Supported Ionenes as Reagents and Catalysts for Several Substitution Reactions in Toluene
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Several ionene bromides were used as reagents for the displacement of decyl methanesulfonate into 1-bromodecane.They were reactive when adsorbed by silica gel.The enhanced activities of the ionenes were hardly dependent on their structures and molecular weights but decreased gradually with increasing the amount of ionene adsorbed by silica gel.Ionene chlorides exhibited a similar enhancement of reactivity when adsorbed by silica gel.However, unlike the ionenes, a large increase in activity due to adsorption was not observed with pendant-type polycations such as poly(4-vinylpyridinium bromide) and poly.The silica gel-supported ionenes also exhibited excellent catalytic activities for solid-liquid-solid triphase substitution reactions, particularly for the reactions between 1-bromodecane and such inorganic salts as consisted of relatively hard-basic nucleophilic anions.
- Ohtani, Noritaka,Chida, Kosaku,Serita, Hajime,Matsunaga, Toshiaki,Kimura, Chikai
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p. 4371 - 4378
(2007/10/02)
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- Novel Functional Group Transformations involving Alkyl Phenyl Selenones
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Alkyl phenyl selenones readily undergo substitution reactions, and are valuable precursors of epoxides on reaction with aldehydes inthe presence of bases.
- Krief, Alain,Dumont, Willy,Denis, Jean-Noel
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p. 571 - 572
(2007/10/02)
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- Method of making aluminum alkyls
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A method of making aluminum alkyls utilizing an uncatalyzed exchange reaction wherein an aluminum trialkyl is reacted with an alkyl iodide in which the alkyl group differs from at least one of the alkyl groups of the aluminum trialkyl to form an aluminum trialkyl having the alkyl radical of the alkyl iodide reactant and an alkyl iodide having the alkyl radical of the aluminum trialkyl reactant. In particular, triethyl aluminum is reacted with methyl iodide to form trimethylaluminum and ethyl iodide. Aralkyl groups may be substituted for the alkyl groups to produce corresponding aralkyl compounds.
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