- Preparation method of P-chloromethyl styrene
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The invention relates to the field of organic chemistry, in particular to a preparation method of p-chloromethyl styrene. The invention provides a preparation method of p-chloromethyl styrene, which comprises the following step: carrying out elimination reaction on 1-(2-chloroethyl)-4-chloromethylbenzene under alkaline conditions to prepare the p-chloromethyl styrene. According to the preparation method, the reaction raw materials with relatively low price are utilized, the manufacturing cost is reduced, the manufacturing process is simple and safe, various side reactions are less, the product conversion rate is high, the purity is high, and thus a good industrialization prospect can be realized.
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Paragraph 0054-0066
(2021/05/01)
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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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- 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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supporting information
p. 3403 - 3408
(2019/04/01)
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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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supporting information
p. 7962 - 7965
(2019/07/12)
-
- Organocatalytic Chlorination of Alcohols by P(III)/P(V) Redox Cycling
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A catalytic system for the chlorination of alcohols under Appel conditions was developed. Benzotrichloride is used as a cheap and readily available chlorinating agent in combination with trioctylphosphane as the catalyst and phenylsilane as the terminal reductant. The reaction has several advantages over other variants of the Appel reaction, e.g., no additional solvent is required and the phosphane reagent is used only in catalytic amounts. In total, 27 different primary, secondary, and tertiary alkyl chlorides were synthesized in yields up to 95%. Under optimized conditions, it was also possible to convert epoxides and an oxetane to the dichlorinated products.
- Longwitz, Lars,Jopp, Stefan,Werner, Thomas
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p. 7863 - 7870
(2019/06/27)
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- NMP-mediated chlorination of aliphatic alcohols with aryl sulfonyl chloride for the synthesis of alkyl chlorides
-
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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supporting information
p. 2793 - 2800
(2018/11/06)
-
- Ferric(III) Chloride Catalyzed Halogenation Reaction of Alcohols and Carboxylic Acids Using α,α-Dichlorodiphenylmethane
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A new method for chlorination of alcohols and carboxylic acids, using α,α-dichlorodiphenylmethane as the chlorinating agent and FeCl3 as the catalyst, was developed. The method enables conversions of various alcohols and carboxylic acids to their corresponding alkyl and acyl chlorides in high yields under mild conditions. Particulary interesting is the observation that the respective alkyl bromides and iodides can be generated from alcohols when either LiBr or LiI are present in the reaction mixtures.
- Lee, Chang-Hee,Lee, Soo-Min,Min, Byul-Hana,Kim, Dong-Su,Jun, Chul-Ho
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supporting information
p. 2468 - 2471
(2018/04/25)
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- BBr3-Assisted Preparation of Aromatic Alkyl Bromides from Lignin and Lignin Model Compounds
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For the first time, BBr3-assisted nucleophilic substitution was applied to a variety of β-O-4 and α-O-4 model compounds for the highly effective cleavage of different C-O bonds, including C-Oα-OH, Cβ-O/Cα-O and CMe-O bonds (99% conversion for most cases). Without any pretreatment, the substitution proceeds at room temperature in the absence of any catalyst, or additive, selectively affording phenols and important organic synthesis reagents, aromatic alkyl bromides, in high to excellent yields (up to 98%). Preliminary studies also highlight the prospect of this method for the effective cleavage of different types of C-O bonds in real lignin. A total 14 wt % yield of aromatic alkyl bromide, 4-(1,2-dibromo-3-hydroxypropyl)benzene-1,2-diol (10), has been obtained from an extracted lignin through this method.
- Li, Xuan,He, Jianghua,Zhang, Yuetao
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supporting information
p. 11019 - 11027
(2018/09/06)
-
- 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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- Polymethylhydrosiloxane reduction of carbonyl function catalysed by titanium tetrachloride
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Reduction of aromatic aldehydes and ketones into the corresponding methylene derivatives by polymethylhydrosiloxane in the presence of titanium tetrachloride as catalyst was achieved in good to excellent yields ranging from 55-90%. The reaction took place under relatively mild conditions and smoothly led to the desired target molecules in the presence of other functional groups such as halogens, hydroxyl, nitro and methoxy groups. However, in the reduction of the substrate with two methoxy groups in close proximity (1,2-positions), the reaction necessitated a larger amount of the titanium catalyst and a longer reaction time to complete the reduction of the carbonyl function due to a likely complex formation of titanium tetrachloride with the methoxy groups.
- Jumbam, Ndze D.,Makaluza, Siyavuya,Masamba, Wayiza
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p. 179 - 184
(2018/04/20)
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- Ketone-catalyzed photochemical C(sp3)–H chlorination
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Photoexcited arylketones catalyze the direct chlorination of C(sp3)–H groups by N- chlorosuccinimide. Acetophenone is the most effective catalyst for functionalization of unactivated C–H groups while benzophenone provides better yields for benzylic C–H functionalization. Activation of both acetophenone and benzophenone can be achieved by irradiation with a household compact fluorescent lamp. This light-dependent reaction provides a better control of the reaction as compared to the traditional chlorination methods that proceed through a free radical chain propagation mechanism.
- Han, Lei,Xia, Ji-Bao,You, Lin,Chen, Chuo
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p. 3696 - 3701
(2017/06/13)
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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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- Catalytic halodefluorination of aliphatic carbon-fluorine bonds
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A variety of halosilanes, in conjunction with aluminum catalysts, convert fluorocarbons into higher halocarbons. Bromination and iodination of fluorocarbons are more effective than chlorination in terms of yield and activity. The mechanism for the reaction is investigated utilizing experimental and computational evidence and preliminary results suggest an alternate mechanism to that reported for the related hydrodefluorination reaction.
- Goh, Kelvin K.K.,Sinha, Arup,Fraser, Craig,Young, Rowan D.
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p. 42708 - 42712
(2016/05/19)
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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 51; 132; 137; 162
(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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- Trichloroisocynuric acid/DMF as efficient reagent for chlorodehydration of alcohols under conventional and ultrasonic conditions
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A new and efficient method for the chlorodehydration of alcohols utilizing TCCA/DMF is described. Various alcohols can be converted smoothly into their corresponding alkyl chlorides in high yields under mild conditions with short reaction times. Taylor & Francis Group, LLC.
- Venkana, Purugula,Kumar, Mukka Satish,Rajanna, Kamatala Chinna,Ali, Mir Moazzam
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- The direct anti-Markovnikov addition of mineral acids to styrenes
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The direct anti-Markovnikov addition of strong Bronsted acids to alkenes remains an unsolved problem in synthetic chemistry. Here, we report an efficient organic photoredox catalyst system for the addition of HCl, HF and also phosphoric and sulfonic acids to alkenes, with complete regioselectivity. These transformations were developed using a photoredox catalyst in conjunction with a redox-active hydrogen atom donor. The nucleophile counterion plays a critical role by ensuring high reactivity, with 2,6-lutidinium salts typically furnishing the best results. The nature of the redox-active hydrogen atom donor is also consequential, with 4-methoxythiophenol providing the best reactivity when 2,6-lutidinium salts are used. A novel acridinium sensitizer provides enhanced reactivity within several of the more challenging reaction manifolds. This Article demonstrates how nucleophilic addition reactions mediated by photoredox catalysis can change the way electrophilic and homofugal precursors are constructed.
- Wilger, Dale J.,Grandjean, Jean-Marc M.,Lammert, Taylor R.,Nicewicz, David A.
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p. 720 - 726
(2014/08/05)
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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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- Preparation of ionic liquid-based vilsmier reagent from novel multi-purpose dimethyl formamide-like ionic liquid and its application
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In continuation of research to explore the applied potential of DMF-like ionic liquid, the ionic liquid version of N,N-dimethyliminiumchloride (Vilsmier reagent) has been synthesized from DMF-like ionic liquid and tested effectively for its capacity to achieve more useful organic transformations. The results show that DMF-like ionic liquid is world's first task specific ionic liquid which has catalyzed numerous diverse type of reaction and is multipurpose in its application. Thus a new term for this DMF-like ionic liquid has been coined that is DMF-like "multipurpose" ionic liquid. Copyright
- Hullio, Ahmed Ali,Mastoi
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scheme or table
p. 1647 - 1657
(2012/09/21)
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- A facile and green protocol for nucleophilic substitution reactions of sulfonate esters by recyclable ionic liquids [bmim][X]
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Ionic liquids [bmim][X] (X = Cl, Br, I, OAc, SCN) are highly efficient reagents for nucleophilic substitution reactions of sulfonate esters derived from primary and secondary alcohols. The counter anions (X-) of the ionic liquids, [bmim][X], effectively replace the sufonates affording the corresponding substitution products such as alkyl halides, acetates, and thiocyanides in excellent yields. The newly developed protocol is very environmentally attractive because the reactions use stoichiometric amounts of ionic liquids as sole reagents in most cases and do not require additional solvents, any other activating reagents, non-conventional equipment, or special precautions. Moreover, these ionic liquids can be readily recycled without loss of reactivity, making the whole process greener.
- Liu, Yajun,Xu, Yongnan,Jung, Sun Ho,Chae, Junghyun
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supporting information
p. 2692 - 2698,7
(2012/12/12)
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- A facile and green protocol for nucleophilic substitution reactions of sulfonate esters by recyclable ionic liquids [bmim][X]
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Ionic liquids [bmim][X] (X = Cl, Br, I, OAc, SCN) are highly efficient reagents for nucleophilic substitution reactions of sulfonate esters derived from primary and secondary alcohols. The counter anions (X-) of the ionic liquids, [bmim][X], effectively replace the sufonates affording the corresponding substitution products such as alkyl halides, acetates, and thiocyanides in excellent yields. The newly developed protocol is very environmentally attractive because the reactions use stoichiometric amounts of ionic liquids as sole reagents in most cases and do not require additional solvents, any other activating reagents, non-conventional equipment, or special precautions. Moreover, these ionic liquids can be readily recycled without loss of reactivity, making the whole process greener. Georg Thieme Verlag KG Stuttgart · New York.
- Liu, Yajun,Xu, Yongnan,Jung, Sun Ho,Chae, Junghyun
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supporting information
p. 2692 - 2698
(2013/01/15)
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- N-(tert -butoxycarbonyl)- N -[(triethylenediammonium)sulfonyl]azanide: A convenient sulfamoylation reagent for alcohols
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A convenient and efficient procedure is described for the sulfamoylation of alcohols using N-(tert-butoxycarbonyl)-N-[(triethylenediammonium)sulfonyl] azanide (1). The ambient temperature stable reagent 1 reacts with phenols as well as primary and secondary alcohols to give high to modest yields. The relative reaction rate of substrates was determined (primary > phenol > secondary ? tertiary). The reagent's utility as a selective sulfamoylation reagent with polyols is also demonstrated.
- Armitage, Ian,Berne, Alexander M.,Elliott, Eric L.,Fu, Mingkun,Hicks, Frederick,McCubbin, Quentin,Zhu, Lei
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p. 2626 - 2629
(2012/07/28)
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- In situ phosphine oxide reduction: A catalytic appel reaction
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Several important reactions in organic chemistry thrive on stoichiometric formation of phosphine oxides from phosphines. To avoid the resulting burden of waste and purification, cyclic phosphine oxides were evaluated for new catalytic reactions based on in situ regeneration. First, the ease of silane-mediated reduction of a range of cyclic phosphine oxides was explored. In addition, the compatibility of silanes with electrophilic halogen donors was determined for application in a catalytic Appel reaction based on in situ reduction of dibenzophosphole oxide. Under optimized conditions, alcohols were effectively converted to bromides or chlorides, thereby showing the relevance of new catalyst development and paving the way for broader application of organophosphorus catalysis by in situ reduction protocols. Copyright
- Van Kalkeren, Henri A.,Leenders, Stefan H. A. M.,Hommersom, C. Rianne A.,Rutjes, Floris P. J. T.,Van Delft, Floris L.
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scheme or table
p. 11290 - 11295
(2011/10/19)
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- A structure-activity study of Ni-catalyzed alkyl-alkyl kumada coupling. Improved catalysts for coupling of secondary alkyl halides
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A structureactivity study was carried out for Ni catalyzed alkylalkyl Kumada-type cross coupling reactions. A series of new nickel(II) complexes including those with tridentate pincer bis(amino)amide ligands (RN2N) and those with bidentate mixed amino-amide ligands (RNN) were synthesized and structurally characterized. The coordination geometries of these complexes range from square planar, tetrahedral, to square pyramidal. The complexes had been examined as precatalysts for cross coupling of nonactivated alkyl halides, particularly secondary alkyl iodides, with alkyl Grignard reagents. Comparison was made to the results obtained with the previously reported Ni pincer complex [( MeN2N)NiCl]. A transmetalation site in the precatalysts is necessary for the catalysis. The coordination geometries and spin-states of the precatalysts have a small or no influence. The work led to the discovery of several well-defined Ni catalysts that are significantly more active and efficient than the pincer complex [(MeN2N)NiCl] for the coupling of secondary alkyl halides. The best two catalysts are [(HNN)Ni(PPh3)Cl] and [(HNN)Ni(2,4-lutidine)Cl]. The improved activity and efficiency was attributed to the fact that phosphine and lutidine ligands in these complexes can dissociate from the Ni center during catalysis. The activation of alkyl halides was shown to proceed via a radical mechanism.
- Ren, Peng,Vechorkin, Oleg,Von Allmen, Kim,Scopelliti, Rosario,Hu, Xile
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supporting information; experimental part
p. 7084 - 7095
(2011/06/26)
-
- Impact of the carbon chain length of novel palladium(ll) Complexes on interaction with DNA and cytotoxic activity
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A series of Pd(II) complexes with a benzenealkyl dicarboxlate chain, with the formulas [Pd(Ln)(bipy)].mH2O (bipy = 2,2'-bipyridine, complex 1: L1 = phenylmalonate, m = 2.5; complex 2: L2 = benzylmalonate, m = 1; complex 3: L3 = phenethylmatonate, m = 2; complex 4: L4 = phenylpropylmalonate, m = 5), have been prepared in an attempt to correlate factors about the carbon chain of the compounds with DNA binding and cytotoxic activity. The binding of complexes with fish sperm DNA (FS-DNA) was carried out by UV absorption and fluorescence spectra. A gel electrophoresis assay demonstrated the ability of the complexes to cleave the pBR322 plasmid DNA. The cytotoxic effects of these complexes were examined on four cancer cell lines, HeLa, Hep-G2, KB, and AGZY-83a. The four complexes exhibited cytotoxic specificity and a significant cancer cell inhibitory rate. An apparent dependence of DNAbinding properties and cytotoxicity on the carbon chain length was obtained: the longer the carbon chain length, the higher the efficiency of DNA-binding and the greater the cytotoxicity. 2010 American Chemical Society.
- Gao, Enjun,Zhu, Mingchang,Liu, Lei,Huang, Yun,Wang, Lei,Shi, Chuyue,Zhang, Wanzhong,Sun, Yaguang
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experimental part
p. 3261 - 3270
(2010/06/13)
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- Aromatic cation activation of alcohols: Conversion to alkyl chlorides using dichlorodiphenylcyclopropene
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(Chemical Equation Presented) A novel paradigm for the activation of alcohols toward nucleophilic displacement via formation of cyclopropenium ethers is described. The conversion of a range of alcohol substrates to the corresponding alkyl chlorides occurs rapidly upon treatment with 3,3-dichloro-1,2-diphenylcyclopropene. 1H NMR data support the intermediacy of a cyclopropenium intermediate, and the reaction is demonstrated to proceed primarily via the SN2 mechanism for 1-phenylethanol. A total of 12 examples of substrate scope are provided.
- Kelly, Brendan D.,Lambert, Tristan H.
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supporting information; experimental part
p. 13930 - 13931
(2009/12/25)
-
- A new and more efficient synthesis of methylene acetals
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A new and efficient synthesis of benzyl chlorides and methylene acetals by use of 2,4-dichloro-6-methoxy[l,3,5]triazine (MeOTCT) and dimethyl sulfoxide has been developed. Chlorides are the major products for benzyl alcohols, while methylene acetals are the major products for secondary alcohols. This procedure provides the highest yields so far for methylene acetals of steroids. A plausible mechanism is proposed on the basis of the experiments. Georg Thieme Verlag Stuttgart.
- Chu, Guobiao,Zhang, Yanqiao,Li, Chunbao,Zhang, Yuqing
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experimental part
p. 3828 - 3832
(2010/03/03)
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- Reactivity of chlorinating agents/PPh3 for the chlorination of alcohols and carboxylic acids: a comparative study
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The reactivity of chlorinating agents was examined with the aid of 1H NMR using competitive reactions between selected chlorinating agents and CBr4 towards alcohols and carboxylic acids. The reactivity was greatly dependent on the type of substituent on the chlorinating agents. COCCl3 and CN substituted trichloromethyl groups enhanced the reactivity of the chlorinating agent with PPh3 for the chlorination of alcohols and carboxylic acids.
- Pluempanupat, Wanchai,Chantarasriwong, Oraphin,Taboonpong, Piyada,Jang, Doo Ok,Chavasiri, Warinthorn
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p. 223 - 226
(2007/10/03)
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- A mild and efficient synthesis of chloroesters by the cleavage of cyclic and acyclic ethers using Bi(NO3)3·5H2O as a catalyst under solvent-free conditions
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A facile, efficient synthesis of chloroesters is described. The reaction of cyclic and acyclic ethers with acid chlorides in the presence of catalytic amounts of Bi(NO3)2·5H2O under solvent-free conditions yielded the corresponding chloroesters. Also, the catalyst can be recovered conveniently and reused efficiently for at least six times.
- Suresh,Suryakiran,Venkateswarlu
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p. 1037 - 1040
(2008/09/16)
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- Iterative stereospecific reagent-controlled homologation of pinacol boronates by enantioenriched α-chloroalkyllithium reagents
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Reaction of pinacol boronates with putative enantioenriched α-chloroalkyllithium species, generated in situ from homochiral α-chloroalkylsulfoxides by sulfoxide ligand exchange with t-BuLi in PhMe at -78 °C, gave chain-extended boronic ester products with generally excellent stereochemical fidelity. Iteration of this stereospecific reagent-controlled homologation (StReCH) process enabled the programmed synthesis of all four stereoisomers of a stereodiad-containing model system (4-benzyl-1,6-diphenylhexan-2-ol) with er ≥ 97:3 in all cases. Copyright
- Blakemore, Paul R.,Burge, Matthew S.
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p. 3068 - 3069
(2008/02/05)
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- An efficient method for chlorination of alcohols using PPh3/Cl3CCONH2
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A new and convenient method for the chlorination of alcohols utilizing PPh3/Cl3CCONH2 is addressed. Various alcohols could smoothly be converted into their corresponding alkyl chlorides in high yield under mild conditions with short reaction times. A mechanism is disclosed with the evidence of inversion of configuration of the analogous alkyl chloride derived from R-(-)-2-octanol.
- Pluempanupat, Wanchai,Chavasiri, Warinthorn
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p. 6821 - 6823
(2007/10/03)
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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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- The chemistry of cyclic carbaphosphazenes: The first observation of (R 2PN)(ClCN)2 (R=Cl, Ph) as a reagent for the conversion of alcohols to aldehydes, ketones, and alkyl chlorides
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The oxidation of nine primary and secondary alcohols to the corresponding aldehydes and ketones has been carried out under mild conditions and in good yields using the cyclocarbaphosphazenes (R2PN)(ClCN)2 [R2P = Cl2 P(1), Ph2P(2)] along with dimethylsulfoxide. While both the P-Cl and C-Cl bonds of the carbaphosphazene can in principle bring about the reaction, we observed an increased preference for the C-Cl bonds over the P-Cl bonds in the oxidation of alcohol. Blocking the reactive P site on the heterocyclic ring with the phenyl groups was found to reduce the yields of the oxidized products, while blocking the C- sites with diethylamino groups resulted in no reaction. In addition, along with DMF, the same cyclocarbaphosphazene has been found to be useful for the conversion of alcohols to alkyl chlorides. Copyright Taylor & Francis Group, LLC.
- Behera, Nabakrushna,Mishra, Pradyumna Kumar,Elias, Anil J.
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p. 2445 - 2452
(2007/10/03)
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- Reagent-controlled asymmetric homologation of boronic esters by enantioenriched main-group chiral carbenoids
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Putative enantioenriched carbenoid species, (R)-1-chloro-2- phenylethylmagnesium chloride (9) and (S)-1-chloro-2-phenylethyllithium (26), generated in situ by sulfoxide ligand exchange from (-)-(Rs,R)-1- chloro-2-phenylethyl p-tolyl sulfoxide (8), effected the stereocontrolled homologation of boronic esters. sec-Alcohols derived from the product boronates by oxidation with basic hydrogen peroxide exhibited % ee closely approaching that of sulfoxide 8 in examples employing Li-carbenoid 26.
- Blakemore, Paul R.,Marsden, Stephen P.,Vater, Huw D.
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p. 773 - 776
(2007/10/03)
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- Solid-state chlorodecarboxylation of mono- and dicarboxylic acids with the Pb(OAc)4-MCl system
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Solid state reactions of acids RCOOH (R = n-C7H15, BuC(Et)H, n-C9H19, PhCH2, PhCH 2CH2, H2C=CH(CH2)8, or MeOOC(CH2)3) with Pb(OAc)4 combined with KCl, NaCl, CdCl2, or NH4Cl in the absence of a solvent and without mechanical activation afford chlorohydrocarbons RCl. The corresponding reactions of acids HOOC(CH2)nCOOH (n = 3-6) give dichloroalkanes Cl(CH2)nCl and γ-butyrolactone (n = 3).
- Nikishin,Sokova,Chizhov,Makhaev,Kapustina
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p. 2200 - 2204
(2007/10/03)
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- "Polysiloxane-Pd" nanocomposites as recyclable chemoselective hydrogenation catalysts
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Polysiloxane-encapsulated "Pd"-nanoclusters were generated by reduction of Pd(OAc)2 with polymethylhydrosiloxane, which functions as a reducing agent as well as a capping material for production and stabilization of catalytically active "Pd"-nanoparticles. Chemoselective hydrogenation of functional conjugated alkenes was achieved by in-situ- or ex-situ-generated polysiloxane-stabilized "Pd"- nanoclusters under mild reaction conditions in high yields. Electron microscopy, UV-vis, and NMR studies of the reaction mixture during the catalytic transformation were performed and, in conjunction with catalyst poisoning experiments, demonstrated unequivocally the role of polysiloxane-encapsulated "Pd"-nanoclusters as the real catalytic species. The recyclability of the "Pd"-nanoclusters was established by reusing the solid left after the reaction.
- Chauhan, Bhanu P. S.,Rathore, Jitendra S.,Bandoo, Tariq
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p. 8493 - 8500
(2007/10/03)
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- A one-pot method for the efficient conversion of aryl- and acyl-substituted methyl alcohols into chlorides
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A one-pot and efficient conversion of aryl- and acyl-substituted methyl alcohols into the corresponding chlorides is described, which involved tosylation with tosyl chloride and triethylamine in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) in CH2Cl2, followed by methanol-facilitated replacement of the tosylates with chloride. This mild method is readily amenable to large-scale synthesis.
- Lai, Gaifa,Tan, Ping-Zhong,Ghoshal, Pallab
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p. 1727 - 1732
(2007/10/03)
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- An efficient route to alkyl chlorides from alcohols using the complex TCT/DMF
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(formula presented) Efficient conversion of alcohols and β-amino alcohols to the corresponding chlorides (and bromides) can be carried out at room temperature in methylene chloride, using 2,4,6-trichloro[1,3,5]triazine and N,N-dimethyl formamide. This procedure can also be applied to optically active carbinols.
- De Luca, Lidia,Giacomelli, Giampaolo,Porcheddu, Andrea
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p. 553 - 555
(2007/10/03)
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- Triphenylphosphine/2,3-dichloro-5,6-dicyanobenzoquinone as a new, selective and neutral system for the facile conversion of alcohols, thiols and selenols to alkyl halides in the presence of halide ions
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A mixture of triphenylphosphine (Ph3P) and 2,3-dichloro-5,6-dicyanobenzoquinone in CH2Cl2 affords a complex which in the presence of R4NX (X=Cl, Br, I) converts alcohols, thiols and selenols into their corresponding alkyl halides in high yields at room temperature. The method is highly selective for the conversion of 1° alcohols in the presence of 2° ones and also 1° and 2° alcohols in the presence of 3° alcohols, thiols, epoxides, trimethylsilyl- and tetrahydropyranyl ethers, 1,3 dithianes, disulfides, and amides.
- Iranpoor,Firouzabadi,Aghapour,Vaez zadeh
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p. 8689 - 8693
(2007/10/03)
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- Interpretation of retention indices in gas chromatography for establishing structures of isomeric products of alkylarenes radical chlorination
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By an example of previously uncharacterized products obtained by alkylarenes radical chlorination was demonstrated that combination of various interpretation methods applied to the retention indices (RI) in the gas chromatography on the standard nonpolar phases (comparison of RI of products and initial compounds, characteristics of succession of the chromatographic elution of the structural isomers with the use of estimation of molecular dynamic parameters, application of the additive schemes to RI calculation, and using of structural analogy CH3?Cl for testing the results obtained) permitted unambiguous identification of the structure even without data of mass spectrometry.
- Zenkevich
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p. 270 - 280
(2007/10/03)
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- Using secondary alpha deuterium kinetic isotope effects to determine the stereochemistry of an E2 reaction; the stereochemistry of the E2 reaction of 1-chloro-2-phenylethane with potassium tert-butoxide in tert-butyl alcohol
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Isotopic labelling studies have shown that the E2 reaction of 1-chloro-2-phenylethane with potassium tert-butoxide in tert-butyl alcohol occurs via an anti-periplanar stereochemistry. This demonstrates that the different secondary alpha deuterium kinetic isotope effects found for the high and low base concentrations and in the presence of 18-crown-6 ether are because of changes in transition state structure that occur when the form of the reacting base changes rather than to a change in the stereochemistry of the reaction.
- Smith,Crowe,Westaway
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p. 1145 - 1152
(2007/10/03)
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- Binding of spiperone analogs at 5-HT(2A) serotonin receptors
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Although spiperone displays good selectivity for 5-HT(2A) versus 5- HT(2C) serotonin receptors, it suffers from high affinity for 5-HT(1A) and dopamine D2 receptors. In order to determine a) the contribution of various structural features to 5-HT(2A) affinity, and b) if spiperone binds in a manner comparable to that of the 5-HT2 antagonist ketanserin, several abbreviated analogs of spiperone were prepared and examined. Removal of the spiperone fluoro group enhances 5-HT(2A) affinity several-fold, but does not improve its selectivity. The butyrophenone carbonyl group is not a major contributor to binding, but removal of the triazaspirodecanone carbonyl group reduces affinity at all receptor populations by about 100-fold. For a series of spiperone analogs, a three- to four-atom chain seems optimal for 5-HT(2A) affinity. On the basis of the structure-activity findings, it is concluded that ketanserin and spiperone likely bind at 5-HT(2A) receptors in a dissimilar manner.
- Khorana, Nantaka,Bondarev, Mikhail,Dukat, Malgorzata,Herrick-Davis, Katharine,Egan, Christina,DuPre, Ann,Smith, Carol,Teitler, Milt,Glennon, Richard A.
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p. 657 - 667
(2007/10/03)
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- Chlorine substitution reactions using trichloroisocyanuric acid with triphenylphosphine
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Trichloroisocyanuric acid with triphenylphosphine in anhydrous acetonitrile will convert alcohols into alkyl halides, carboxylic acids into acid chlorides, 1,3-diketones into vinyl chlorides, and amides into nitriles.
- Hiegel,Ramirez,Barr
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p. 1415 - 1419
(2007/10/03)
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- Halogen-exchange reactions between alkyl fluorides and boron trihalides or tetrahalides. A convenient synthesis of alkyl halides from alkyl fluorides
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A simple and effective method for converting fluoroalkanes to their corresponding chloro-, bromo- and iodo-alkanes using commercially available boron trihalides and titanium tetrahalides is described. - Keywords: Halogen-exchange reactions; Alkyl fluorides; Boron trihalides; Titanium tetrahalides; NMR spectroscopy; Mass spectrometry
- Namavari, Mohammad,Satyamurthy, N.,Barrio, Jorge R.
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- Phosphorylated Nitrogen Mustards. Part 2. Anchimeric Assistance of the Fragmentation of N-(2-Chloroethyl)-2-Arylethylphosphoroamidates
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N-(2-Chloroethyl)phosphoric amido esters containing a 2-arylethyl ester function undergo thermal fragmentation to the 2-arylchloroethane, aziridine and a methaphosphate intermediate.
- Roux, Charlotte le,Modro, Agnes M.,Modro, Tomasz A.
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