- Indium-catalyzed direct chlorination of alcohols using chlorodimethylsilane-benzil as a selective and mild system
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The InCl3-catalyzed reaction of alcohols with chlorodimethylsilane (HSiMe2Cl) in the presence of benzil gave the corresponding organic chlorides under mild conditions. Benzil significantly changes the reaction course because the reducing product through dehydroxyhydration was obtained in the absence of benzil. The secondary or tertiary alcohols were effectively chlorinated. The substrates bearing acid-sensitive functional groups were also applied to this system. The highly selective chlorination of the tertiary site was observed in the competitive reaction between tertiary and primary alcohols. The highly coordinated hydrosilane generated from benzil and HSiMe2Cl is an important intermediate. Copyright
- Yasuda, Makoto,Yamasaki, Satoshi,Onishi, Yoshiyuki,Baba, Akio
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- Phosphine functionalized polyphosphazenes: soluble and re-usable polymeric reagents for highly efficient halogenations under Appel conditions
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In this paper we present the preparation and application of a novel soluble phosphine functionalized polyphosphazene (poly[3-(diphenylphosphino)propylamino]phosphazene) and investigate its application as a polymeric reagent. Upon chlorination of the pendant phosphine groups, the polymer was found to facilitate the rapid and efficient transformation of alcohols to the corresponding chlorides and bromides under Appel-type conditions. Reaction times followed by 31P NMR spectroscopy are shown to be rapid (several minutes) and the yields for the transformation of alcohols to the corresponding halides are in the range 80–99?%. The facile recovery of the oxidized polymeric agent by precipitation is also described, offering a significant advantage over notoriously difficult to remove small molecule phosphine oxide by-products. Furthermore the regeneration of the reactive phosphine chloride pendant groups is demonstrated, which could be efficiently re-used in a further chlorination reaction. Graphical abstract: [Figure not available: see fulltext.]
- K?nig, Michael,Linhardt, Anne,Brüggemann, Oliver,Teasdale, Ian
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- Vicarious Nucleophilic Chloromethylation of Nitroaromatics
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Nitroaromatics substituted with electron-acceptor or electron-donor groups undergo vicarious nucleophilic substitution with the lithium salt of dichloromethane to provide chloromethyl-substituted nitroaromatics in good to high yields. The methodology represents a new strategy for the synthesis of benzyl chlorides.
- Khutorianskyi, Viktor V.,Klepetá?ová, Blanka,Beier
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- Promotion of Appel-type reactions by N-heterocyclic carbenes
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N-Heterocyclic carbenes (NHCs) have been extensively used as a versatile class of catalysts and ligands in organocatalytic and organometallic chemistry. However, there are only a small number of synthetic applications where they act as reagents. Here we demonstrate that NHCs can be used as stoichiometric redox reagents for Appel-type halogenation reactions of alcohols. This new reactivity reveals a fresh and interesting aspect and enriches the chemistry of NHCs in an underexplored area. The potential of performing this chemical transformation at the catalytic level using an NHC-oxide derivative is also investigated.
- Hussein, Mohanad A.,Nguyen, Thanh Vinh
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- N -Hydroxyphthalimide/benzoquinone-catalyzed chlorination of hydrocarbon C-H bond using N -chlorosuccinimide
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The direct chlorination of C-H bonds has received considerable attention in recent years. In this work, a metal-free protocol for hydrocarbon C-H bond chlorination with commercially available N-chlorosuccinimide (NCS) catalyzed by N-hydroxyphthalimide (NHPI) with 2,3-dicyano-5,6-dichlorobenzoquinone (DDQ) functioning as an external radical initiator is presented. Aliphatic and benzylic substituents and also heteroaromatic ones were found to be well tolerated. Both the experiments and theoretical analysis indicate that the reaction goes through a process wherein NHPI functions as a catalyst rather than as an initiator. On the other hand, the hydrogen abstraction of the C-H bond conducted by a PINO species rather than the highly reactive N-centered radicals rationalizes the high chemoselectivity of the monochlorination obtained by this protocol as the latter is reactive towards the C(sp3)-H bonds of the monochlorides. The present results could hold promise for further development of a nitroxy-radical system for the highly selective functionalization of the aliphatic and benzylic hydrocarbon C-H.
- Li, Zi-Hao,Fiser, Béla,Jiang, Biao-Lin,Li, Jian-Wei,Xu, Bao-Hua,Zhang, Suo-Jiang
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- Synthetic Strategy and Performances of a UV-Curable Poly Acryloyl Phosphinate Flame Retardant by Carbene Polymerization
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A route to synthesize poly ethyl (4-acrylamidebenzyl) phosphinate (PPAC) was discussed and the optimal route was determined. Diethyl benzylphosphonate was synthesized by Arbuzov reaction, then, a nitryl was introduced onto the aromatic ring by the nitration reaction of ethyl benzylphosphonate. Subsequently the carbene polymerization of the product was carried out. Finally, the nitryls were reduced and amidated to introduce the acryloyl group into the prepolymer to obtain the target product (PPAC). PPAC can rapidly photopolymerize under UV light irradiation. The addition of PPAC decreased the smoke production rate (SPR), CO2 production (CO2P), and CO production (COP) of the UV-cured resin.
- Yu, Jia,Li, Minglei,Yu, Yong,Gao, Yanjing,Liu, Jiancheng,Sun, Fang
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- Gallium-catalyzed reductive chlorination of carboxylic acids with copper(II) chloride
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Described herein is the direct chlorination of carboxylic acids using copper(II) chloride via a gallium(III)-catalyzed reduction in the presence of a hydrosiloxane. During this reductive chlorination, the counteranions of CuCl2 functioned as a chloride source.
- Sakai, Norio,Nakajima, Takumi,Yoneda, Shinichiro,Konakahara, Takeo,Ogiwara, Yohei
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- Intramolecular Electron Transfer in the Anion Radicals of Nitrobenzyl Halides
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One-electron reduction of nitrobenzyl halides produces the anion radicals which subsequently undergo intramolecular electron transfer and decompose into nitrobenzyl radicals and halide ions.The optical absorption spectra of the initial anion radicals (λmax ca. 300-310 nm) and the subsequently formed nitrobenzyl radicals (λmax = 359 and 400 for the para and ortho, respectively) are quite intense (ε ca. 104 M-1 cm-1 in most cases) and significantly different.This enables identification of the various species and measurement of the rates of intramolecular electron transfer or C-X bond scission.The rates are 4*103, 1.7*105, and 5.7*105 s-1 for p-nitrobenzyl chloride, bromide, and iodide, respectively.The ortho derivatives decomposed nearly twice as rapidly while the meta decomposed much more slowly.The anion radical of p-nitrobenzyl bromide has pKa = 2.8, and the protonated form is found to undergo the intramolecular transfer ca. 60 times more slowly than the anion radical.The pattern of reactivity of the various anion radicals is rationalized in terms of spin density and charge distribution at the various positions on the ring and in terms of the electrophilicities of the halogens.
- Neta, P.,Behar, D.
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- NMP-mediated chlorination of aliphatic alcohols with aryl sulfonyl chloride for the synthesis of alkyl chlorides
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NMP-mediated chlorination of aliphatic alcohols has been developed for the synthesis of alkyl chlorides. This facile, efficient and practical approach used simple and readily available aryl sulfonyl chlorides as the chlorination reagent for the construction of C–Cl bond in good to excellent yields with mild conditions and broad substrate scope.
- Zheng, Dagui,Mao, Liu-Liang,Zhu, Xian-Hong,Zhou, An-Xi
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- Bambusurils Bearing Nitro Groups and Their Further Modifications
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Bambusurils are recently developed neutral anion receptors that show a high affinity towards many inorganic anions, not only in organic solvents but also in water. However, the number of water-soluble bambusurils and also those bearing functional groups is very limited. In this paper we report the synthesis of four- and six-membered bambusurils containing eight and twelve nitro groups. All the nitro groups on the bambusuril portals could be transformed into amino functions, which provided the macrocycles with water solubility and allowed their further modification. For example, we have demonstrated the conversion of amino groups on the bambusurils into the corresponding urea-functionalized bambusuril derivatives. We also report the first example of a bambusuril bearing only two functional groups, which was prepared by the condensation of two different glycolurils.
- Yawer, Mirza Arfan,Sleziakova, Kristina,Pavlovec, Lukas,Sindelar, Vladimir
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- A Visible-Light-Induced α-H Chlorination of Alkylarenes with Inorganic Chloride under NanoAg@AgCl
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An efficient, photocatalytic chlorination of alkylarene α-H groups using NaCl/HCl as a chlorine source has been developed, which involves a radical mechanism under visible-light (including sunlight) conditions. A chlorine radical is proposed to be formed by an electron transfer from chloride ion to O2 in air through the bandgap hole of the semiconductor AgCl. The chlorination protocol is characterized by its use of natural sunlight or other visible light, mild conditions, cheap source of chlorine, green solvent, and high selectivity. The yield of benzylchloride is 95 % with a toluene conversion as high as 40 %, which rivals traditional chlorination methods.
- Liu, Shouxin,Zhang, Qi,Li, Huiying,Yang, Yihua,Tian, Xia,Whiting, Andrew
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- Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
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The direct selective halogenation of unactivated C(sp3)-H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450-500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons.
- Liu, Shouxin,Zhang, Qi,Tian, Xia,Fan, Shiming,Huang, Jing,Whiting, Andrew
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- New applications of tungsten hexachloride (WCl6) in organic synthesis. Halo-de-hydroxylation and dihalo-de-oxo-bisubstitution reactions
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Tungsten hexachloride (WCl6) has been used for the halo-de-hydroxylation and dihalo-de-oxo-bisubstitution reactions of benzylic alcohols, benzaldehydes, acyloins, and epoxides to their chlorides, gem-dichlorides, vic-trichlorides, and vic-dichlorides respectively.
- Firouzabadi, Habib,Shiriny, Farhad
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- A duality of mechanisms for the fragmentation of substituted benzyloxychlorocarbenes
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Substituted benzyloxychlorocarbenes (X-PhCH2OCCl) were generated photochemically at 25 °C in dichloroethane from appropriate diazirine precursors. Fragmentations of the carbenes produced were determined by laser flash photolysis. The data (X, kfrag in s-1) were: p-Me, 2.6 × 105; p-Ph, 8.3 × 104; H, 6.0 × 104; p-Cl, 5.2 × 104; m-Cl, 1.3 × 105; p-F3C, 2.1 × 106; p-O2N, 6.3 × 106. A Hammett correlation of log kfrag versus σ+ was parabolic. The curvature was taken to imply the gradual change of the fragmentation mechanism from predominantly heterolytic for X-PhCH2CCl with electron-donating X (with developing positive charge on the benzylic carbon in the transition state) to predominantly homolytic for carbenes with electron-withdrawing X. This idea was supported by computational studies. Copyright
- Moss, Robert A.,Ma, Yan,Sauers, Ronald R.
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- Visible Light-Catalyzed Benzylic C-H Bond Chlorination by a Combination of Organic Dye (Acr+-Mes) and N-Chlorosuccinimide
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By combining "N-chlorosuccinimide (NCS)"as the safe chlorine source with "Acr+-Mes"as the photocatalyst, we successfully achieved benzylic C-H bond chlorination under visible light irradiation. Furthermore, benzylic chlorides could be converted to benzylic ethers smoothly in a one-pot manner by adding sodium methoxide. This mild and scalable chlorination method worked effectively for diverse toluene derivatives, especially for electron-deficient substrates. Careful mechanistic studies supported that NCS provided a hydrogen abstractor "N-centered succinimidyl radical,"which was responsible for the cleavage of the benzylic C-H bond, relying on the reducing ability of Acr?-Mes.
- Xiang, Ming,Zhou, Chao,Yang, Xiu-Long,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
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p. 9080 - 9087
(2020/08/14)
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- Thiourea-Mediated Halogenation of Alcohols
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The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
- Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
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p. 12901 - 12911
(2020/11/26)
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- Lewis Base Catalysis Enables the Activation of Alcohols by means of Chloroformates as Phosgene Substitutes
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Nucleophilic substitutions (SN) are typically promoted by acid chlorides as sacrificial reagents to improve the thermodynamic driving force and lower kinetic barriers. However, the cheapest acid chloride phosgene (COCl2) is a highly toxic gas. Against this background, phenyl chloroformate (PCF) was discovered as inherently safer phosgene substitute for the SN-type formation of C?Cl and C?Br bonds using alcohols. Thereby, application of the Lewis bases 1-formylpyrroldine (FPyr) and diethylcyclopropenone (DEC) as catalysts turned out to be pivotal to shift the chemoselectivity in favor of halo alkane generation. Primary, secondary and tertiary, benzylic, allylic and aliphatic alcohols are appropriate starting materials. A variety of functional groups are tolerated, which includes even acid labile moieties such as tert-butyl esters and acetals. Since the by-product phenol can be isolated, a recycling to PCF with inexpensive phosgene would be feasible on a technical scale. Eventually, a thorough competitive study demonstrated that PCF is indeed superior to phosgene and other substitutes.
- Zoller, Ben,Stach, Tanja,Huy, Peter H.
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p. 5637 - 5643
(2020/09/21)
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- Nucleophilic Substitutions of Alcohols in High Levels of Catalytic Efficiency
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A practical method for the nucleophilic substitution (SN) of alcohols furnishing alkyl chlorides, bromides, and iodides under stereochemical inversion in high catalytic efficacy is introduced. The fusion of diethylcyclopropenone as a simple Lewis base organocatalyst and benzoyl chloride as a reagent allows notable turnover numbers up to 100. Moreover, the use of plain acetyl chloride as a stoichiometric promotor in an invertive SN-type transformation is demonstrated for the first time. The operationally straightforward protocol exhibits high levels of stereoselectivity and scalability and tolerates a variety of functional groups.
- Stach, Tanja,Dr?ger, Julia,Huy, Peter H.
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supporting information
p. 2980 - 2983
(2018/05/28)
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- A General Catalytic Method for Highly Cost- and Atom-Efficient Nucleophilic Substitutions
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A general formamide-catalyzed protocol for the efficient transformation of alcohols into alkyl chlorides, which is promoted by substoichiometric amounts (down to 34 mol %) of inexpensive trichlorotriazine (TCT), is introduced. This is the first example of a TCT-mediated dihydroxychlorination of an OH-containing substrate (e.g., alcohols and carboxylic acids) in which all three chlorine atoms of TCT are transferred to the starting material. The consequently enhanced atom economy facilitates a significantly improved waste balance (E-factors down to 4), cost efficiency, and scalability (>50 g). Furthermore, the current procedure is distinguished by high levels of functional-group compatibility and stereoselectivity, as only weakly acidic cyanuric acid is released as exclusive byproduct. Finally, a one-pot protocol for the preparation of amines, azides, ethers, and sulfides enabled the synthesis of the drug rivastigmine with twofold SN2 inversion, which demonstrates the high practical value of the presented method.
- Huy, Peter H.,Filbrich, Isabel
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supporting information
p. 7410 - 7416
(2018/04/30)
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- Systematic Evaluation of Sulfoxides as Catalysts in Nucleophilic Substitutions of Alcohols
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Herein, a method for the nucleophilic substitution (SN) of benzyl alcohols yielding chloro alkanes is introduced that relies on aromatic sulfoxides as Lewis base catalysts (down to 1.5 mol-%) and benzoyl chloride (BzCl) as reagent. A systematic screening of various sulfoxides and other sulfinyl containing Lewis bases afforded (2-methoxyphenyl)methyl sulfoxide as optimal catalyst. In contrast to reported formamide catalysts, sulfoxides also enable the application of plain acetyl chloride (AcCl) as reagent. In addition, it was demonstrated that weakly electrophilic carboxylic acid chlorides like BzCl promote Pummerer rearrangement of sulfoxides already at room temperature. This side-reaction also provided the explanation, why sulfoxide catalyzed SN-reactions of alcohols do not allow the effective production of aliphatic and electron deficient chloro alkanes. Comparison experiments provided further insight into the reaction mechanism.
- Motsch, Sebastian,Schütz, Christian,Huy, Peter H.
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supporting information
p. 4541 - 4547
(2018/09/13)
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- Visible Light-Induced Oxidative Chlorination of Alkyl sp3 C-H Bonds with NaCl/Oxone at Room Temperature
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A visible light-induced monochlorination of cyclohexane with sodium chloride (5:1) has been successfully accomplished to afford chlorocyclohexane in excellent yield by using Oxone as the oxidant in H2O/CF3CH2OH at room temperature. Other secondary and primary alkyl sp3 C-H bonds of cycloalkanes and functional branch/linear alkanes can also be chlorinated, respectively, under similar conditions. The selection of a suitable organic solvent is crucial in these efficient radical chlorinations of alkanes in two-phase solutions. It is studied further by the achievement of high chemoselectivity in the chlorination of the benzyl sp3 C-H bond or the aryl sp2 C-H bond of toluene.
- Zhao, Mengdi,Lu, Wenjun
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supporting information
p. 4560 - 4563
(2017/09/11)
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- SNAr catalysis enhanced by an aromatic donor-acceptor interaction; Facile access to chlorinated polyfluoroarenes
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Selective catalytic SNAr reaction of polyfluoroaryl C-F bonds with chloride is shown. Stoichiometric TMSCl makes the reaction exergonic and allows catalysis, which involves ground state elevation of chloride, aromatic donor-acceptor interactions, and stabilization of the Meisenheimer complex. Traditional cross-coupling of the products is now possible and demonstrates the utility.
- Senaweera, Sameera,Weaver, Jimmie D.
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supporting information
p. 7545 - 7548
(2017/07/12)
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- Three including animal pen oxygen radical porphyrin the synthetic method of the compound of
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The invention discloses a synthesis method of benzyloxy-containing porphyrin compounds. A propanoic acid-glacial acetic acid-nitrobenzene mixed solvent conventional heating process is utilized to synthesize two novel porphyrin compounds at high yield, namely meso-tetra(3-methoxy-4-benzyloxyphenyl)porphyrin and meso-tetra[4-(4-nitrobenzyloxy)phenyl]porphyrin; and the synthesis of meso-tetra(4-benzyloxyphenyl)porphyrin is improved. The invention also discloses a synthesis technique of benzyloxy-substituted aromatic aldehydes, namely 4-benzyloxybenzaldehyde, 3-methoxy-4-benzyloxybenzaldehyde and 4-(4-nitrobenzyloxy)benzaldehyde; and the synthesis technique is simple to operate, has the advantages of high yield, low cost and high purity, and is suitable for industrial production.
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Paragraph 0015; 0039
(2017/04/29)
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- A save the cost of the process for the preparation of the nitro benzyl alcohol
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The invention discloses a cost-saving preparation method of p-nitrobenzyl alcohol. The key points of the technical scheme are as follows: according to the cost-saving preparation method of the p-nitrobenzyl alcohol, p-nitrotoluene is taken as a starting raw material and reacts with chlorine gas to obtain p-nitrobenzyl chloride, and then the p-nitrobenzyl chloride is hydrolyzed in an alkaline solution to obtain p-nitrobenzyl alcohol. Compared with the prior art, the cost-saving preparation method of the p-nitrobenzyl alcohol has the following beneficial effects: the reaction system is simple and the raw material is cheap and easily available; the preparation cost is low and no hazardous waste is generated, so that the preparation method accords with the green production ideal; the cost-saving preparation method is simple in process, simple and convenient to operate, short in reaction time, high in efficiency and suitable for large-scale production.
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Paragraph 0020-0022
(2017/04/07)
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- METHOD OF CONVERTING ALCOHOL TO HALIDE
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The present invention relates to a method of converting an alcohol into a corresponding halide. This method comprises reacting the alcohol with an optionally substituted aromatic carboxylic acid halide in presence of an N-substituted formamide to replace a hydroxyl group of the alcohol by a halogen atom. The present invention also relates to a method of converting an alcohol into a corresponding substitution product. The second method comprises: (a) performing the method of the invention of converting an alcohol into the corresponding halide; and (b) reacting the corresponding halide with a nucleophile to convert the halide into the nucleophilic substitution product.
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Page/Page column 97; 98
(2017/01/02)
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- Formamides as Lewis Base Catalysts in SNReactions—Efficient Transformation of Alcohols into Chlorides, Amines, and Ethers
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A simple formamide catalyst facilitates the efficient transformation of alcohols into alkyl chlorides with benzoyl chloride as the sole reagent. These nucleophilic substitutions proceed through iminium-activated alcohols as intermediates. The novel method, which can be even performed under solvent-free conditions, is distinguished by an excellent functional group tolerance, scalability (>100 g) and waste-balance (E-factor down to 2). Chiral substrates are converted with excellent levels of stereochemical inversion (99 %→≥95 % ee). In a practical one-pot procedure, the primary formed chlorides can be further transformed into amines, azides, ethers, sulfides, and nitriles. The value of the method was demonstrated in straightforward syntheses of the drugs rac-Clopidogrel and S-Fendiline.
- Huy, Peter H.,Motsch, Sebastian,Kappler, Sarah M.
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supporting information
p. 10145 - 10149
(2016/08/16)
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- Aromatic cation activation: Nucleophilic substitution of alcohols and carboxylic acids
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A new method for the nucleophilic substitution of alcohols and carboxylic acids using aromatic tropylium cation activation has been developed. This article reports the use of chloro tropylium chloride for the rapid generation of alkyl halides and acyl chlorides under very mild reaction conditions. It demonstrates, for the first time, the synthetic potential of tropylium cations in promoting chemical transformations.
- Nguyen, Thanh V.,Bekensir, Alp
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supporting information
p. 1720 - 1723
(2014/04/17)
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- Sulfite formation versus chlorination of benzyl alcohols with thionyl chloride
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Recently, we have reported the photolytic decay of a library of para-substituted dibenzylic sulfites in a Srinivasan-Griffin-Rayonet photochemical reactor. In an attempt to synthesize the complete library for that study we discovered that bis(p-methoxybenzyl) sulfite and bis(p-phenoxybenzyl) sulfite could not be formed and only their corresponding benzyl chlorides were synthesized. Thus, sulfite formation versus chlorination of a range of para-substituted benzyl alcohols with thionyl chloride was investigated. Sulfite formation was observed to be parabolically related to Swain and Lupton's Field ?-values while chloride formation was found to be linearly related to Swain and Lupton's Field ?-values.
- Rodriguez, Deana A.,Priefer, Ronny
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p. 3045 - 3048
(2014/05/20)
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- Silver-catalyzed decarboxylative chlorination of aliphatic carboxylic acids
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Decarboxylative halogenation of carboxylic acids, the Hunsdiecker reaction, is one of the fundamental functional group transformations in organic chemistry. As the initial method requires the preparations of strictly anhydrous silver carboxylates, several modifications have been developed to simplify the procedures. However, these methods suffer from the use of highly toxic reagents, harsh reaction conditions, or limited scope of application. In addition, none is catalytic for aliphatic carboxylic acids. In this Article, we report the first catalytic Hunsdiecker reaction of aliphatic carboxylic acids. Thus, with the catalysis of Ag(Phen)2OTf, the reactions of carboxylic acids with t-butyl hypochlorite afforded the corresponding chlorodecarboxylation products in high yields under mild conditions. This method is not only efficient and general, but also chemoselective. Moreover, it exhibits remarkable functional group compatibility, making it of more practical value in organic synthesis. The mechanism of single electron transfer followed by chlorine atom transfer is proposed for the catalytic chlorodecarboxylation.
- Wang, Zhentao,Zhu, Lin,Yin, Feng,Su, Zhongquan,Li, Zhaodong,Li, Chaozhong
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experimental part
p. 4258 - 4263
(2012/04/10)
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- Treatment of alcohols with tosyl chloride does not always lead to the formation of tosylates
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Treatment of substituted benzyl alcohols with tosyl chloride resulted in the formation of the corresponding chlorides, not the usual tosylates. A series of experiments demonstrated that it was possible to predict whether chlorination or tosylation would occur for substituted benzyl alcohols and pyridine methanols. Treatment of electron withdrawing group-substituted benzyl alcohols with tosyl chloride gave the corresponding chlorides in moderate yields under mild conditions, which provided a simple way to directly prepare chlorides from alcohols.
- Ding, Rui,He, Yong,Wang, Xiao,Xu, Jingli,Chen, Yurong,Feng, Man,Qi, Chuanmin
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experimental part
p. 5665 - 5673
(2011/09/20)
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- Efficient organic transformations mediated by ZrOCl28H 2O in Water
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Operationally simple and environmentally benign methods for some organic transformations comprising reductive coupling of sulfonyl chlorides, chemoselective deoxygenation of sulfoxides, and halogenation of alcohols mediated by ZrOCl28H2O/MX in water have been developed.
- Jafarpour, Maasoumeh,Rezaeifard, Abdolreza,Heidari, Mahdieh
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experimental part
p. 1470 - 1482
(2011/10/05)
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- Chlorination of various substrates in subcritical carbon tetrachloride
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Various aliphatic hydrocarbons and the side chains of aromatic hydrocarbons were chlorinated in subcritical carbon tetrachloride. Chlorination of aromatic compounds including 1,4-disubstituted benzenes was investigated. Ketones and sulfones were stable under the employed conditions. Sulfoxides were converted into sulfides in a low to modest yields. The coupling adducts between olefins and carbon tetrachloride were obtained from the reactions of olefins.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Horaguchi, Takaaki
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experimental part
p. 2881 - 2888
(2010/06/16)
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- PREPARATION AND UTILITY OF SUBSTITUTED INDOLES
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Disclosed herein are substituted indoles of Formula I, processes of preparation there of, pharmaceutical compositions thereof, and methods of their use there of.
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Page/Page column 38
(2008/06/13)
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- 4-Aminophenyldiphenylphosphinite (APDPP), a new heterogeneous and acid scavenger phosphinite - Conversion of alcohols, trimethylsilyl, and tetrahydropyranyl ethers to alkyl halides with halogens or N-halosuccinimides
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A new heterogeneous phosphinite, 4-aminophenyldiphenylphosphinite (APDPP), is prepared and used for the efficient conversion of alcohols, trimethylsilyl ethers, and tetrahydropyranyl ethers to their corresponding bromides, iodides, and chlorides in the presence of molecular halogens or N-halosuccinimides. The amino group in this phosphinite acts as an acid scavenger and removes the produced acid. A simple filtration easily removes the phosphinate by-product.
- Iranpoor, Nasser,Firouzabadi, Habib,Gholinejad, Mohammad
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p. 1006 - 1012
(2007/10/03)
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- Supported tetramethylamonium nitrate/silicasulfuric acid as a useful reagent for nitration aromatic compounds under solvent-free conditions
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A variety of aromatic compounds are nitrated to the parent nitro aromatic compounds under solvent-free conditions using supported tetramethylammonium nitrate/silicasulfuric acid as a useful reagent. This methodology is useful for nitration of activated and deactivated aromatic rings. Copyright Taylor & Francis, Inc.
- Hajipour, Abdol R.,Zarei, Amin,Khazdooz, Leila,Ruoho
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p. 2237 - 2241
(2007/10/03)
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- A novel stereoselective one-pot conversion of alcohols into alkyl halides mediated by N,N′-diisopropylcarbodiimide
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Alcohols can be converted in high yields to the corresponding alkyl halides in a one-pot procedure via the corresponding O-alkylisourea; very short reaction times are possible when microwave irradiation is used.
- Crosignani, Stefano,Nadal, Brice,Li, Zhengning,Linclau, Bruno
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p. 260 - 261
(2007/10/03)
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- Oxidation of benzylic alcohols and ethers to carbonyl derivatives by nitric acid in dichloromethane
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Nitric acid in dichloromethane may be successfully employed for the oxidation of benzylic alcohols and ethers to the corresponding carbonyl compounds. The proposed method proved to be of general applicability, affording very good yields of aldehydes and ketones and showing interesting chemoselectivity in many instances, allowing competitive aromatic nitration to be avoided, as well as - in the case of aldehydes - any further oxidation to carboxylic acids. The reaction probably proceeds by a radical mechanism, the active species in the oxidation process being NO2. Competitive formation of nitro esters was observed in some cases, whereas poor results were obtained with allylic and non-benzylic substrates. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Strazzolini, Paolo,Runcio, Antonio
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p. 526 - 536
(2007/10/03)
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- Thionyl chloride-benzotriazole in methylene chloride: A convenient solution for conversion of alcohols and carboxylic acids expeditiously into alkyl chlorides and acid chlorides by simple titration
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A solution of 1:1 equivalent of thionyl chloride and benzotriazole in dry methylene chloride efficiently transforms alcohols and carboxylic acids into the corresponding alkyl chlorides and acid chlorides respectively at room temperature, with excellent yields by simple titration.
- Chaudhari, Sachin S.,Akamanchi, Krishnacharya G.
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p. 1763 - 1765
(2007/10/03)
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- 2-chloro-1,3-dimethylimidazolinium chloride. 3. Utility for chlorination, oxidation, reduction, and rearrangement reactions
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2-Chloro-1,3-dimethylimidazolinium chloride (1), which can act as a powerful dehydrating equivalent to DCC (2), is also applicable to chlorination, oxidation, reduction, and rearrangement under nearly neutral conditions. The utility of 1 for these reactions is described.
- Isobe, Toshio,Ishikawa, Tsutomu
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p. 5832 - 5835
(2007/10/03)
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- Synthesis of New Reactive Cationic Products
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Two new bicationic products - quaternary ammonium salts - with increased substantivity for subsequent quaternization of cellulose, have been synthesised.Assignment of the chemical structure is made by applying the IR and 1H-NMR methods alongside the analy
- Muresan, Augustin,Vata, Mihai,Tataru, Lucia,Balba, Doina
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- Gas-phase substituent effects in highly electron-deficient systems. II. stabilities of 1-aryl-2,2,2-trifluoroethyl cations based on chloride-transfer equilibria
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The relative stabilities of 1-aryl-2,2,2-trifluoroethyl cations were determined based on the chloride ion-transfer equilibria in the gas phase. An application of the Yukawa-Tsuno equation to this substituent effect on the equilibrium constants gave a remarkably larger r+ of 1.53 and a ρ of-10.6, supporting our previous conclusion that the highly electron-deficient benzylic carbocation systems are characterized by extremely high resonance demands. This r+ value, furthermore, conformed a linear relationship between the r+ value and the relative stability of the unsubstituted member of the respective benzylic carbocations, clearly demonstrating a continuous spectrum of varying resonance demands characteristic of the stabilities of carbocations. The π-delocalization of the positive charge into the aryl π-system increases with the destabilization of a carbocation by the α-substituent(s) linked to the central carbon. In addition, the r + value of 1.53 for 1-aryl-2,2,2-trifluoroethyl cations was found to be in complete agreement with that for the solvolysis of 1-aryl-2,2,2- trifluoroethyl tosylates in 80% aq acetone. This reveals that the r+ value observed for this solvolysis must be the intrinsic resonance demand of a highly electron-deficient cationic transition state in the SN 1 ionizing process. The identity of the r+ value was consistent with our previous observation for other benzylic carbocation systems, indicating that the degree of the π-delocalization of the positive charge is identical between the cationic transition state and an intermediate cation for all benzylic systems, which cover a wide range of reactivity and stability of the carbocation. This leads us to the conclusion that the geometry of the transition state in the ionizing process of the SN1 solvolysis, which is a highly endothermic reaction, closely resembles the high-energy product, an intermediate cation.
- Mishima, Masaaki,Inoue, Hiroki,Fujio, Mizue,Tsuno, Yuho
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p. 1163 - 1169
(2007/10/03)
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- Oxidation of Aromatic Compounds. I. Oxidation of Methyl Derivatives of Nitrobenzene and Aniline in the System HSO3F-PbO2
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Low-temperature oxidation of methyl derivatives of nitrobenzene and aniline in the system HSO3F-PbO2 proceeds with intermediate formation of radical cations and results in replacement of hydrogen in one or two methyl groups or yields compounds of the diphenylmethane and biphenyl series.
- Rudenko, A. P.,Korovina, N. S.,Aver'yanov, S. F.
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p. 1077 - 1083
(2007/10/03)
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- Detection of Carbonyl Oxide from Singlet p-Nitrophenylchlorocarbene and Oxygen
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p-Nitrophenylchlorocarbene reacts with oxygen with a rate constant 2.24107 M-1 s-1 in isooctane at 25 deg C giving rise to an intermediate carbonyl oxide which absorbs at 400 nm.
- Liu, Michael T. H.,Bonneau, Roland,Jefford, Charles W.
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p. 1482 - 1483
(2007/10/02)
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- Rapid Cleavage Reactions of Haloaromatic Radical Anions Measured with Fast-Scan Cyclic Voltammetry
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Cyclic voltammetry at scan rates from 10 mV/s to 1E6 V/s has been used to characterize the reduction of aryl and benzyl halides in acetonitrile solutions containing 0.6 M tetraethylammonium perchlorate.The use of very rapid scan rates is made possible with electrodes of micrometer dimensions.The kinetics and mechanism of the reduction process have been evaluated by digital simulation of the recorded voltammograms.The radical anion generated at the electrode surface is found to have a half-life ranging from less than 100 ns in the case of 4'-bromoacetophenone to 70 ms for the case of m-nitrobenzyl chloride.The reduction mechanism for the aryl halides is consistent with the ECE-DISP1 mechanism.Thus following initial one-electron reduction, halogen bond cleavage occurs resulting in a radical that is subsequently reduced.For the compounds with relatively long half-lives (>1ms) the results in thus work are in good agreement with prior investigations with cyclic voltammetry.Good agreement is also obtained with compounds that have a short half-life ( ca. 1 μs) which have been characterized by the technique of redox catalysis.However, the measured rate constants differ with previously reported values which were estimated or measured at the extreme time limits of classical electrochemical techniques.
- Wipf, David O.,Wightman, R. Mark
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p. 4286 - 4291
(2007/10/02)
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- Reduction of carbonyl compounds promoted by silicon hydrides under the influence of trimethylsilyl-based reagents
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The synthetic utility of hydrosilanes under the influence of trimethylsilyl-based reagents as new reducing systems is described. 1,1,3,3-Tetramethyldisiloxane (TMDS) reagent in combination with iodotrimethylsilane or bromotrimethylsilane produces alkyl halides from aldehydes in good to excellent yields.Polymethylhydrosiloxane (PMS) in the presence of iodotrimethylsilane also produces benzyl iodides in excellent yields.On the contrary, PMS reagent was found unsuitable for the synthesis of benzyl bromides.Similary, TMDS reagent in combination with trimethylsilyl triflate produces symmetrical ethers from aldehydes without concomitant formation of competitive products.Under similar conditions, PMS reagent failed to provide the expected symmetrical ethers and Friedel-Crafts products were formed.Reduction of quinones to hydroquinones is also described.
- Aizpurua, Jesus M.,Lecea, Begona,Palomo, Claudio
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p. 2342 - 2347
(2007/10/02)
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- ALKYL HALIDES FROM ALCOHOLS: AN EFFECTIVE METHOD UNDER MILD CONDITIONS
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Primary alkyl chlorides and bromides are obtained from the carbinol precursors and an organic amine hydrohalide under straightforward Mitsunobu conditions.
- Alpegiani, Marco,Bedeschi, Angelo,Perrone, Ettore
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p. 393 - 394
(2007/10/02)
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- DESULFONYLATION OF ARYLMETHANESULFONYL CHLORIDES CATALYZED BY DICLHOROTRIS(TRIPHENYLPHOSPHINE)RUTHENIUM(II)
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Reactions of arylmethanesulfonyl chlorides catalyzed by dichlorotris(triphenylphosphine)ruthenium(II) (1) have been studied.Desulfonylation occurred when arylmethanesulfonyl chlorides were treated with catalytic amounts of the ruthenium(II) catalyst to give chloromethylarene in high yields.No addition of the sulfonyl chloride to olefin was observed when the reaction was carried out in the presence of an equimolar amount of an olefin such as styrene.However, the rate of disappearance of the sulfonyl chloride was accelerated by addition of an olefin.The desulfonylation is assumed to proceed by a redox transfer promoted homolytic mechanism in the coordination sphere of the catalyst.In the presence of large excess of styrenes, arylmethanesulfonyl chlorides added to the olefins to give 1:1 adducts competitively with the desulfonylation yielding chloromethylarenes.
- Kamigata, Nobumasa,Suzuki, Norihiro,Kobayashi, Michio
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p. 139 - 144
(2007/10/02)
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- Halogenations of S-Benzyl-S-phenylsulfoximides and Base-induced Rearrangements of Their N- and α-Halo Derivatives to N-Sulfinylimines
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The reactions of S-benzyl- and S-(p-nitrobenzyl)sulfoximides 1a, b with N-bromosuccinimide or tert-butyl hypochlorite gave the corresponding N-halosulfoximides 2a, b or 3a, b, respectively, in good yields.The N-bromo-S-(p-nitrobenzyl)sulfoximide 2b decomp
- Yoshida, Toyokichi,Naruto, Shunsuke,Uno, Hitoshi,Nishimura, Haruki
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p. 4346 - 4351
(2007/10/02)
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