- Epoxy-terminated self-assembled monolayers containing internal urea or amide groups
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We report the synthesis of new coupling agents with internal amide or urea groups possessing an epoxy-terminal group and trimethoxysilyl-anchoring group. The structural characterizations of the corresponding self-assembled monolayers (SAMs) were performed by polarization modulation infrared reflection adsorption spectroscopy (PM-IRRAS). The molecular assembly is mainly based on the intermolecular hydrogen-bonding between adjacent amide or urea groups in the monolayers. Because of the steric hindrance of amide or urea groups, the distance between the alkyl chains is too large to establish van der Waals interactions, inducing their disorder. The reactivity of the epoxy-terminal groups was successfully investigated through reaction with a fluorescent probe. We show that SAMs containing internal urea or amide groups exhibited a higher density of accessible epoxide groups than the corresponding long-chain (C22) glycidyl-terminated SAM.
- Ramin, Micha?l A.,Le Bourdon, Gwéna?lle,Heuzé, Karine,Degueil, Marie,Buffeteau, Thierry,Bennetau, Bernard,Vellutini, Luc
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- Synthesis of methacrylate-functionalized phosphonates and phosphates with long alkyl-chain spacers and their self-aggregation in aqueous solutions
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Polymerizable amphiphilic organophosphorous compounds were synthesized and their self-aggregation behavior was investigated. The studied molecules contain a hydrophilic phosphorus end group, an alkyl chain spacer with a variable length from 3 to 11 CH2 groups and a polymerizable methacrylic group at the other chain end. Thus, the molecules represent a class of polymerizable surfactants. Two different reaction methods were used; either unsaturated alcohols or bromine-containing alcohols were applied as starting compounds for the preparation of the organophosphorous surfactants. The self-aggregation and micelle formation of the prepared compounds were investigated in aqueous solution by dynamic light scattering measurements. The critical micelle concentration of the P-containing amphiphiles was in all cases smaller than 0.040 mol/l and strongly dependent on the polarity of the phorphorous head group and the chain length of the spacer. Graphical abstract: [Figure not available: see fulltext.] The synthesis of organophosphorous amphiphiles as surface active monomers for the modification of metal oxide surfaces is presented. The spacer between the phosphorous head group and the methacrylate group was varied with regard to their length and composition. The self-aggregation behavior of these methacrylate-functionalized phosphates and phosphonates surfactants was investigated.
- Francova, Denisa,Kickelbick, Guido
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- The stabilization and bio-functionalization of iron oxide nanoparticles using heterotelechelic polymers
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Iron oxide nanoparticles (IONPs) are important tools for nanobiotechnology applications. However, aqueous instability and non-specific biodistribution problems limit the applications of IONPs. Considering this, α-phosphonic acid, ω-dithiopyridine function
- Boyer, Cyrille,Bulmus, Volga,Priyanto, Priyanto,Teoh, Wey Yang,Amal, Rose,Davis, Thomas P.
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- Reducing properties of 1,2-diaryl-1,2-disodiumethanes
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1,2-Diphenyl- and 1-phenyl-2-(2-pyridyl)-1,2-disodiumethane efficiently dehalogenate vic-dibromoderivatives, affording the corresponding alkenes. The reaction proceeds rapidly, under mild conditions and is tolerant of a variety of functional groups (alcohol, carboxylic acid, ester and amide). This procedure was successfully extended to similar vic-disubstituted compounds.
- Azzena, Ugo,Pittalis, Mario,Dettori, Giovanna,Madeddu, Simona,Azara, Emanuela
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- A direct, straightforward conversion of methoxymethyl ethers into acetates
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The direct transformation of MOM-protected alcohols into the corresponding acetates by acetic anhydride/ferric chloride in CH2Cl2, in a one-step process and good to excellent yields, is reported. The reaction has been applied to a variety of substrates and occurs with retention of configuration.
- Bosch,Petschen,Guerrero
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Read Online
- Catalytic Difluorination of Olefins
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Molecular editing with fluorine is a validated strategy for modulating the structure and function of organic systems. In the current arsenal of catalytic dihalogenation technologies, the direct generation of the vicinal difluoride moiety from simple olefins without a prefunctionalization step remains conspicuously absent. Herein we report a catalytic, vicinal difluorination of olefins displaying broad functional group tolerance, using inexpensive p-iodotoluene as the catalyst. Preliminary efforts toward the development of an enantioselective variant are also disclosed.
- Molnár, István Gábor,Gilmour, Ryan
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- Manganese-mediated acetylation of alcohols, phenols, thiols, and amines utilizing acetic anhydride
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Manganese(II) chloride-catalyzed acetylation of alcohols, phenols thiols and amines with acetic anhydride is reported. This method is environment-friendly and economically viable as it involves inexpensive, relatively benign catalyst, mild reaction condition, and simple workup. Acetylation is performed under the solvent-free condition at ambient temperature and acetylated products obtained in good to excellent yields. Primary, secondary heterocyclic amines, and phenols with various functional groups are smoothly acetylated in good yields. This method exhibits exquisite chemoselectivity, the amino group is preferentially acetylated in the presence of a hydroxyl/thiol group.
- Jain, Isha,Sharma, Ramandeep,Malik, Payal
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supporting information
p. 2952 - 2960
(2019/09/13)
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- A General Acid-Mediated Hydroaminomethylation of Unactivated Alkenes and Alkynes
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In comparison to the extensively studied metal-catalyzed hydroamination reaction, hydroaminomethylation has received significantly less attention despite its considerable potential to streamline amine synthesis. State-of-the-art protocols for hydroaminomethylation of alkenes rely largely on transition-metal catalysis, enabling this transformation only under highly designed and controlled conditions. Here we report a broadly applicable, acid-mediated approach to the hydroaminomethylation of unactivated alkenes and alkynes. This methodology employs cheap, readily available, and bench-stable reactants and affords the desired amines with excellent functional group tolerance and impeccable regioselectivity. The broad scope of this transformation, as well as mechanistic investigations and in situ domino functionalization reactions are reported.
- Kaiser, Daniel,Tona, Veronica,Gon?alves, Carlos R.,Shaaban, Saad,Oppedisano, Alberto,Maulide, Nuno
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supporting information
p. 14639 - 14643
(2019/09/17)
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- PRODUCTION OF AMINES VIA A HYDROAMINOALKYLATION REACTION
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Provided is a process for producing an amine via a hydroaminoalkylation reaction of a non-aromatic C-C double bond or C-C triple bond, said process comprising a step of reacting a compound comprising a non-aromatic C-C double bond or C-C triple bond with a reactive component which is obtainable by combining an aminal or a hemiaminal ether with an acidic medium comprising trifluoroacetic acid, wherein the aminal contains two amino groups independently selected from a secondary and a tertiary amino group that are linked by a methylene group wherein one hydrogen atom may be replaced by a further substituent, and at least one of the amino groups carries a hydrogen atom at a carbon atom bound in α-position to its nitrogen atom, and the hemiaminal ether contains a secondary or a tertiary amino group which carries a hydrogen atom at a carbon atom bound in α-position to its nitrogen atom, and the secondary or tertiary amino group is linked to an alkoxy group by a methylene group wherein one hydrogen atom may be replaced by a further substituent.
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Page/Page column 61
(2019/12/04)
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- Cyclopropanation of Terminal Alkenes through Sequential Atom-Transfer Radical Addition/1,3-Elimination
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An operationally simple method to affect an atom-transfer radical addition of commercially available ICH2Bpin to terminal alkenes has been developed. The intermediate iodide can be transformed in a one-pot process into the corresponding cyclopropane upon treatment with a fluoride source. This method is highly selective for the cyclopropanation of unactivated terminal alkenes over non-terminal alkenes and electron-deficient alkenes. Due to the mildness of the procedure, a wide range of functional groups such as esters, amides, alcohols, ketones, and vinylic cyclopropanes are well tolerated.
- Tappin, Nicholas D. C.,Michalska, Weronika,Rohrbach, Simon,Renaud, Philippe
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supporting information
p. 14240 - 14244
(2019/08/26)
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- Strongly Reducing, Visible-Light Organic Photoredox Catalysts as Sustainable Alternatives to Precious Metals
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Photoredox catalysis is a versatile approach for the construction of challenging covalent bonds under mild reaction conditions, commonly using photoredox catalysts (PCs) derived from precious metals. As such, there is need to develop organic analogues as sustainable replacements. Although several organic PCs have been introduced, there remains a lack of strongly reducing, visible-light organic PCs. Herein, we establish the critical photophysical and electrochemical characteristics of both a dihydrophenazine and a phenoxazine system that enables their success as strongly reducing, visible-light PCs for trifluoromethylation reactions and dual photoredox/nickel-catalyzed C?N and C?S cross-coupling reactions, both of which have been historically exclusive to precious metal PCs.
- Du, Ya,Pearson, Ryan M.,Lim, Chern-Hooi,Sartor, Steven M.,Ryan, Matthew D.,Yang, Haishen,Damrauer, Niels H.,Miyake, Garret M.
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supporting information
p. 10962 - 10968
(2017/08/22)
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- Terpene-based renewable monomers and polymers via thiol-ene additions
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Solvent and radical initiator-free addition of thiols to terpenes ((R)-(+)- and (S)-(-)-limonene and (-)-β-pinene) are described as a simple approach to obtain a wide range of alcohol and/or ester functionalized renewable monomers. (R)-(+)-Limonene (1) and (S)-(-)-limonene (2), presenting different reactivity at the endocyclic and exocyclic double bonds, have yielded the monoaddition or diaddition product by simple variation of the thiol feed ratio. In the same manner, (-)-β-pinene (3) derived alcohol and ester monomers have been prepared. The monomers thus obtained have been characterized, and their behavior in polycondensation has been studied. It has been found that long chain diesters or diols, which were synthesized from a castor oil derived platform chemical, are suitable comonomers and result in polycondensates with number-average molecular weights of up to 25 kDa. Thus, terpene/fatty acid-based polyesters were prepared, and their structure-thermal property relationships were studied.
- Firdaus, Maulidan,Montero De Espinosa, Lucas,Meier, Michael A. R.
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scheme or table
p. 7253 - 7262
(2012/04/04)
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- Palladium-catalyzed allylic acyloxylation of terminal alkenes in the presence of a base
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"Chemical Equation Presentation" The efficiency and the selectivity of the Pd-catalyzed oxidation, in carboxylic acids, of terminal alkenes are strongly improved in the presence of a base. The methodology is particularly well adapted for the oxidation of homoallylic alcohols, for which the resulting acyloxylated products are obtained selectively as E-isomers in fair to good yields. 2010 American Chemical Society.
- Thiery, Emilie,Aouf, Chahinez,Belloy, Julien,Harakat, Dominique,Bras, Jean Le,Muzart, Jacques
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supporting information; experimental part
p. 1771 - 1774
(2010/05/01)
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- Indium-catalyzed retro-claisen condensation
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(Chemical Equation Presented) Retro-aldol reaction: Indium-catalyzed reaction of a 1,3-diketone with an alcohol proceeds under solvent-free conditions by nucleophilic attack of the alcohol on a carbonyl group of the 1,3-diketone and carbon-carbon bond cleavage by a retro-Claisen condensation to give an ester in high yield (see scheme). Using water and an amine as nucleophiles instead of an alcohol gave the corresponding carboxylic acid and amide.
- Kawata, Atsushi,Takata, Kazumi,Kuninobu, Yoichiro,Takai, Kazuhiko
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p. 7793 - 7795
(2008/09/18)
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- Photoacylation of alcohols in neutral medium
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We report here conditions which allow the photoacylation of primary, secondary and tertiary alcohols with N-acetyl-5,7-dinitroindoline under exceptionally mild conditions, at wavelengths harmless to most functional groups, including otherwise photosensitive ones. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Debieux, Jean-Luc,Cosandey, Anne,Helgen, Celine,Bochet, Christian G.
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p. 2073 - 2077
(2008/02/04)
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- A new and highly effective organometallic approach to 1,2-dehalogenations and related reactions
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We investigated the reductive elimination of several functionalized and non-functionalized vic-dibromides with 1,2-diphenyl-, 1,1,2,2-tetraphenyl- and 1-phenyl-2-(2-pyridyl)-1,2-disodioethane. The reaction, involving some of the less expensive organic and inorganic reagents, proceeds under mild conditions, and is tolerant of a variety of functional groups. Extension of this procedure to similar 1,2-disubstituted compounds was also investigated. Reductive eliminations run on stereochemical probe compounds strongly suggest that this reaction proceeds via a "single electron" reductive elimination reaction pathway.
- Azzena, Ugo,Pittalis, Mario,Dettori, Giovanna,Pisano, Luisa,Azara, Emanuela
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p. 3892 - 3900
(2008/03/12)
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- Synthesis of Benzophenone-Containing Analogues of Phosphatidylcholine
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As part of a collaborative study of cellular efflux of cholesterol and phospholipids, photoactivable analogues 4-8 of phosphatidylcholine (PC) having benzophenone groups in the choline moiety and at the end of the C2 and C1 alkyl chains have been synthesized. The efficient preparation via Suzuki coupling of the appropriate long-chain benzophenone-containing carboxylic acid and alcohol and their incorporation by adaptation of known approaches into the acyl- and ether-linked PC analogues 6-8 are described. Development of a method for radiolabeling these PC analogues, via hydrogenation of a double bond in modified side chains, is also described.
- Wang, Pingzhen,Blank, David H.,Spencer, Thomas A.
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p. 2693 - 2702
(2007/10/03)
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- The First Total Synthesis of Tricolorin A
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Keywords: glycosylations; macrocycles; one-pot reactions; total synthesis; tricolorin A
- Lu, Shou-Fu,O'yang, QinQin,Guo, Zhong-Wu,Yu, Biao,Hui, Yong-Zheng
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p. 2344 - 2346
(2007/10/03)
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- Total synthesis of tricolorin A
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Tricolorin A (1), a structurally amazing resin glycoside with promising bioactivities from Ipomoea tricolor cav. (convolvulaceae), was synthesized in a total of 45 steps, with the longest linear sequence of 20 steps and overall yield of 0.65% from D-mannitol. The AB disscharide 19-membered lactone 2 was constructured by a regioselective macrolactonization using Corey-Nicolaou protocol. The macrolactone tetrasaccharide 33 was realized either by 'one- pot two-step' glycosylation procedure or by a stepwise assembly employing the 'armed-disarmed' glycosylation strategy.
- Lu, Shou-Fu,O'Yang, QinQin,Guo, Zhong-Wu,Yu, Biao,Hui, Yong-Zheng
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p. 8400 - 8405
(2007/10/03)
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- Reductive Deacetoxylation of allylic Acetates Using Hexacarbonylmolybdenum(0)
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Aliphatic allylic acetates were reduced to alkenes with hexacarbonylmolybdenum(0) in refluxing dioxane under nitrogen atmosphere.These reactions were accelerated by the addition of H2O. 1-Aryl- or 3-arylallyl acetates caused deacetoxylative allylic homocoupling under the same conditions.
- Masuyama, Yoshiro,Maekawa, Kazunobu,Kurihara, Toshiyuki,Kurusu, Yasuhiko
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p. 2311 - 2313
(2007/10/02)
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- ORGANOBORANES FOR SYNTHESIS. 10. THE BASE-INDUCED REACTION OF BROMINE WITH ORGANOBORNES. A CONVENIENT PROCEDURE FOR THE CONVERSION OF ALKENES INTO ALKYL BROMIDES VIA HYDROBORATION
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The reaction of trialkylboranes with bromine is greatly accelerated by base.Bromination in the presence of sodium hydroxide provides alkyl bromide along with a large amount of the corresponding alcohol.The use of sodium methoxide as a base eliminates this undesirable side reaction and provides an improved yield of alkyl bromide.Consequently, hydroboration, followed by bromination in the presence of sodium methoxide, provides a convenient new procedure for the conversion of alkenes into alkyl bromides.The organoboranes, obtained via hydroboration of terminal alkenes, react with the utilization of all three alkyl groups attached to boron, providing nearly quantitative yields of alkyl bromides. This procedure also accommodates common organic functional groups, as demonstrated by the preparation of methyl 11-bromoundecanoate and 11-bromoundecyl acetate from the corresponding functionally substituted alkenes.Under these conditions, secondary and bulky primary alkyl groups react more sluggishly.However, a procedure involving simultaneous addition of bromine and methanolic sodium methoxide provides improved results for such derivatives.Surprisingly, the base-induced bromination of tri-exo-nobornylborane results in an inversion of configuration at the reaction center to give predominantly endo-2-bromonorbornane.A mechanism is proposed to account for this remarkable inversion.
- Brown, Herbert C.,Lane, Clinton F.
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p. 2763 - 2772
(2007/10/02)
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- Electrofugal Fragmentation of Alkylcobalmin Derivatives Using Cob(I)alamin and Heptamethyl Cob(I)yrinate as Catalysts
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The cob(I)alamin- (1(I) and the heptamethyl cob(I)yrinate- (2(I)) catalyzed transformation of an epoxide to the corresponding saturated hydrocarbon 3 -> 4 -> 5 is examined (see Schemes 1 and 3-5).Under the reaction conditions, the epoxyalkyl acetate 3 is opened by the catalysts with formation of appropriate (β-hydroxyalkyl)-corrinoid derivatives (13, 14, 17, 18, see Schemes 12 and 14).Triggered by a transfer of electrons to the Co-corrin-? system, the Co,C-bond of the intermediates is broken, generating the alkenyl acetate 4 (cf.Schemes 12 and 14) following an electrofugal fragmentation (cf.Schemes 2 and 12).The double bond of 4 is also attacked by the catalysts, leading to the corresponding alkylcorrinoids (15, 19, see Schemes 12 and 14) which is turn are reduced by electrons from metallic zinc, the electron source in the system, inducing a reductive cleavage of the Co,C-bond with production of the saturated monoacetate 5 (see Schemes 2, 5 and 12).In the cascade of steps involved, the transfer of electrons to the intermediate alkylcorrinoids (13-15, 17-19, see Schemes 12 and 14) is shown to be rate-limiting.Comparing the two catalytic species 1(I) and 2(I), it is shown that the ribonucleotide loop protects intermediate alkylcobalmins to some extent from an attack by electrons.The protection function of the ribonucleotide side-chain is shown to be present in alkylcobalamins existing in the base-on form (cf.Chap. 4 and see Scheme 14).
- Fischli, Albert
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p. 1167 - 1190
(2007/10/02)
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