- Photocatalyzed Diastereoselective Isomerization of Cinnamyl Chlorides to Cyclopropanes
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Endergonic isomerizations are thermodynamically unfavored processes that are difficult to realize under thermal conditions. We report a photocatalytic and diastereoselective isomerization of acyclic cinnamyl chlorides to strained cyclopropanes. Quantum mechanical calculations (uM06-2X and DLPNO), including TD-DFT calculations, and experimental studies provide evidence for the energy transfer from an iridium photocatalyst to the allylic chloride substrate followed by C-Cl homolytic cleavage. Subsequent Cla¢ radical migration forms a localized triplet 1,3-diradical intermediate that, after intersystem crossing, undergoes ring-closing to form the desired product. The mild reaction conditions are compatible with a broad range of functional groups to generate chlorocyclopropanes in high yields and diastereoselectivities. A more efficient process is developed by addition of a catalytic amount of a nickel complex, and we propose a novel role for this cocatalyst to recycle an allyl chloride byproduct generated in the course of the reaction. The reaction is also shown to be stereoconvergent, as an E/Z mixture of cinnamyl chlorides furnish the anti-chlorocyclopropane product in high diastereoselectivity. We anticipate that the use of a visible light activated photocatalyst to transform substrates in combination with a transition metal catalyst to recycle byproducts back into the catalytic cycle will provide unique opportunities for the discovery of new reactivity.
- Dykstra, Ryan,Gutierrez, Osvaldo,Martin, Robert T.,Tambar, Uttam K.,Troian-Gautier, Ludovic,Xu, Bin
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supporting information
p. 6206 - 6215
(2020/04/27)
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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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supporting information
p. 2793 - 2800
(2018/11/06)
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- Organocatalytic Synthesis of Oxazolines and Dihydrooxazines from Allyl-Amides: Bypassing the Inherent Regioselectivity of the Cyclization
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A selective and efficient methodology for the construction of either oxazolines or dihydrooxazines from the corresponding allyl-amides is reported. Bypassing the inherent selectivity of the cyclization and depending on the substitution pattern of the substrate, a selective epoxidation-cyclization was developed leading to either the five-membered or the six-membered ring, upon simple and complementary reaction conditions. The cyclization products were obtained in good to excellent yields and high selectivities. (Figure presented.).
- Theodorou, Alexis,Triandafillidi, Ierasia,Kokotos, Christoforos G.
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supporting information
p. 951 - 957
(2018/01/22)
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- Bioactivity and structure–activity relationship of cinnamic acid derivatives and its heteroaromatic ring analogues as potential high-efficient acaricides against Psoroptes cuniculi
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A series of cinnamic acid derivatives and its heteroaromatic ring analogues were synthesized and evaluated for acaricidal activity in vitro against Psoroptes cuniculi, a mange mite. Among them, eight compounds showed the higher activity with median lethal concentrations (LC50) of 0.36–1.07 mM (60.4–192.1 μg/mL) and great potential for the development of novel acaricidal agent. Compound 40 showed both the lowest LC50 value of 0.36 mM (60.4 μg/mL) and the smallest median lethal time (LT50) of 2.6 h at 4.5 mM, comparable with ivermectin [LC50 = 0.28 mM (247.4 μg/mL), LT50 = 8.9 h], an acaricidal drug standard. SAR analysis showed that the carbonyl group is crucial for the activity. The type and chain length of the alkoxy in the ester moiety and the steric hindrance near the ester group significantly influence the activity. The esters were more active than the corresponding thiol esters, amides, ketones or acids. Replacement of the phenyl group of cinnamic esters with α-pyridyl or α-furanyl significantly increase the activity. Thus, a series of cinnamic esters and its heteroaromatic ring analogues with excellent acaricidal activity emerged.
- Chen, Dong-Dong,Zhang, Bing-Yu,Liu, Xiu-Xiu,Li, Xing-Qiang,Yang, Xin-Juan,Zhou, Le
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supporting information
p. 1149 - 1153
(2018/03/05)
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- Method for preparing naftifine hydrochloride
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The invention provides a method for preparing naftifine hydrochloride. The finished naftifine hydrochloride is obtained through subjecting relatively-cheap cinnamyl alcohol, which serves as a raw material, to chlorinating-reagent chlorinating, methyl-amination and 1-chloromethyl naphthalene substitution sequentially, and finally, carrying out acidification salt-forming and crystallization refining. According to the method provided by the invention, all intermediates in first three steps of reactions are subjected to a reaction without purification, process flows are continuous and non-intermittent, the operation is simplified, the yield and production efficiency of the product are increased, and meanwhile, the purity of the product is ensured, so that the method is applicable to industrialization; and meanwhile, the method has the advantages of simple reaction conditions, low cost and environment-friendliness.
- -
-
Paragraph 0039; 0056; 0058
(2018/07/06)
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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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- Continuous-Flow Multistep Synthesis of Cinnarizine, Cyclizine, and a Buclizine Derivative from Bulk Alcohols
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Cinnarizine, cyclizine, buclizine, and meclizine belong to a family of antihistamines that resemble each other in terms of a 1-diphenylmethylpiperazine moiety. We present the development of a four-step continuous process to generate the final antihistamines from bulk alcohols as the starting compounds. HCl is used to synthesize the intermediate chlorides in a short reaction time and excellent yields. This methodology offers an excellent way to synthesize intermediates to be used in drug synthesis. Inline separation allows the collection of pure products and their immediate consumption in the following steps. Overall isolated yields for cinnarizine, cyclizine, and a buclizine derivative are 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1. The incredible bulk: Bulk alcohols are converted continuously into chlorides using HCl in a microflow. A reaction network that consists of four steps and two inline separations leads to the continuous preparation of cinnarizine, cyclizine, and a buclizine derivative with yields of 82, 94, and 87 %, respectively. The total residence time for the four steps is 90 min with a productivity of 2 mmol h-1.
- Borukhova, Svetlana,Nol, Timothy,Hessel, Volker
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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; 107; 108
(2017/01/02)
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- Method for preparing chlorohydrocarbons from alcohols by using aryl sulfonyl chloride as chlorination agent
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The invention provides a method for preparing chlorohydrocarbons from alcohols by using aryl sulfonyl chloride as a chlorination agent. The method comprises the following steps: heating alcohols and aryl sulfonyl chloride in N,N-dialkyl substituted amide to react for 30 minutes, cooling the reaction product to room temperature, adding dichloromethane and water, carrying out extraction and skimming, washing the organic layer with saturated saline water, drying with anhydrous sodium sulfate, steaming to remove the solvent, and carrying out further separation and purification to obtain the chlorohydrocarbons. The method has the characteristics of cheap and accessible chlorination agent, simple technical process, short reaction time and the like, can obtain high reaction under the condition that the aryl sulfonyl chloride consumption is approximate to the stoichiometric quality, and can remove the reaction byproduct aryl sulfonic acid from the reaction mixture.
- -
-
Paragraph 0019; 0020
(2017/01/17)
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- α-Selective Allylation of Isatin Imines Using Metallic Barium
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The Barbier-type allylation of isatin imines with allylic chlorides was achieved by using metallic barium as the promoter. Various α-allylated 3-amino-2-oxindoles were synthesized from the corresponding allylic chlorides and isatin imines. The double-bond geometry of allylic chlorides was retained throughout the reaction. An arylic bromide or iodide functionality of the products was robust to metalation under the optimum reaction conditions.
- Yanagisawa, Akira,Yamafuji, Seiya,Sawae, Toshiki
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supporting information
p. 2019 - 2023
(2016/08/09)
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- Rhodium(ii)-catalyzed intramolecular formal [4 + 3] cycloadditions of dienyltriazoles: Rapid access to fused 2,5-dihydroazepines
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Rhodium(ii)-catalyzed intramolecular [4 + 3] cycloadditions of dienyltriazoles have been developed, which enable the efficient synthesis of various fused 2,5-dihydroazepines. Mechanistically, the titled reaction proceeds via an interesting tandem cyclopropanation/aza-cope rearrangement.
- Tian, Yu,Wang, Yuanhao,Shang, Hai,Xu, Xudong,Tang, Yefeng
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supporting information
p. 612 - 619
(2015/02/05)
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- The use of bromotrichloromethane in chlorination reactions
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Carbon tetrachloride is no longer used as a common solvent due to its toxicity and harmful environmental impact. The synthesis of gem-dichloroalkenes from aldehydes by using triphenylphosphine typically requires carbon tetrachloride as a solvent. We report that stoichiometric bromotrichloromethane in acetonitrile can be used in place of solvent quantities of carbon tetrachloride in this transformation. Similarly, bromotrichloromethane in dichloromethane can be used for the room-temperature Appel reaction of benzyl alcohols to form benzyl chlorides, which is commonly carried out in refluxing carbon tetrachloride. Georg Thieme Verlag Stuttgart New York.
- Newman, Stephen G.,Bryan, Christopher S.,Perez, Didier,Lautens, Mark
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supporting information; experimental part
p. 342 - 346
(2011/03/18)
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- A novel, air-stable phosphine ligand for the palladium-catalyzed suzuki-miyaura cross-coupling reaction of chloro arenes
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(Figure presented) A novel, air-stable phosphine ligand, prepared from readily available 2-bromonitrobenzene and vinylmagnesium bromide, combines with Pd(CH3CN)2Cl2 to afford an effective catalyst for Suzuki-Miyaura cross-coupling of aryl, heteroaryl, and allyl chlorides with phenylboronic acid.
- Ghosh, Raju,Adarsh,Sarkar, Amitabha
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supporting information; experimental part
p. 5320 - 5322
(2010/10/19)
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- Allylic and allenic halide synthesis via NbCl5- and NbBr 5-mediated alkoxide rearrangements
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(Chemical Equation Presented) Addition of NbCl5 or NbBr 5 to a series of magnesium, lithium, or potassium allylic or propargylic alkoxides directly provides allylic or allenic halides. Halogenation formally occurs through a metallahalo-[3,3] rearrangement, although concerted, ionic, and direct displacement mechanisms appear to operate competitively. Transposition of the olefin is equally effective for allylic alkoxides prepared by nucleophilic addition, deprotonation, or reduction. Experimentally, the niobium pentahalide halogenations are rapid, afford essentially pure (E)-allylic or -allenic halides after extraction, and are applicable to a range of aliphatic and aromatic alcohols, aldehydes, and ketones. 2009 American Chemical Society.
- Ravikumar,Yao, Lihua,Fleming, Fraser F.
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supporting information; experimental part
p. 7294 - 7299
(2010/01/16)
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- Direct conversion of aldehydes and ketones to allylic halides by a NbX 5-[3,3] rearrangement
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Sequential addition of vinylmagnesium bromide and NbCl5, or NbBr5, to a series of aldehydes and ketones directly provides homologated, allylic halides. Transposition of the intermediate vinyl alkoxide is envisaged through a metalo-halo-[3,3] rearrangement with concomitant delivery of the halogen to the terminal carbon. The [3,3] rearrangement is equally effective for the conversion of a propargyllic alcohol to the corresponding allenyl bromide. Georg Thieme Verlag Stuttgart.
- Fleming, Fraser F.,Ravikumar,Yao, Lihua
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experimental part
p. 1077 - 1080
(2009/09/29)
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- One-pot formation of allylic chlorides from carbonyl derivatives
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(Chemical Equation Presented) An efficient, one-pot method for the conversion of carbonyl electrophiles to allylic chlorides has been developed, by activating magnesium alkoxides in situ using TiCl4.
- Fuchter, Matthew J.,Levy, Jean-Noel
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supporting information; experimental part
p. 4919 - 4922
(2009/05/31)
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- A novel one-pot conversion of allyl alcohols into primary allyl halides mediated by acetyl halide
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A new and simple method for the synthesis of the primary allyl chlorides and bromides 9-16 from the secondary or tertiary allyl alcohols 3-8 and acyl halide was developed (Scheme 2, Table 1). Non-commercially available secondary and tertiary allyl alcohols were synthesized from the related ketones and aldehydes via the addition of vinylmagnesium chloride. Mechanistic studies indicate that the alcohols were first acetylated by the acetyl halide and then protonated prior to substitution by the halide, Cl- or Br -, via an 5N2′ reaction, to yield the primary halides (Scheme 5).
- Kishali, Nurhan,Polat, M. Fatih,Altundas, Ramazan,Kara, Yunus
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- Cyanuric chloride-mediated synthesis of allylic chloride - Ipso- versus tele-substitution
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Synthesis of unsymmetrical allylic chlorides has been accomplished using cyanuric chloride in combination with DMF through ipso-substitution and tele-substitution by judicious choice of the substituents at appropriate positions of unsymmetrical allyl alcohols, taking care of their electronic and steric properties. Copyright Taylor & Francis Group, LLC.
- Roy, Sanchita,Das, Tarak,Saha, Manabendra,Chaudhuri, Subrata Kumar,Bhar, Sanjay
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p. 4367 - 4370
(2008/03/13)
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- 1-Cinnamyl-4-(2-methoxyphenyl)piperazines: Synthesis, binding properties, and docking to dopamine (D2) and serotonin (5-HT1A) receptors
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Clinical properties of atypical antipsychotics are based on their interaction with D2 dopamine receptor and serotonin 5-HT1A and 5-HT2A receptors. As a part of our research program on new antipsychotics, we synthesized various derivatives of 1-cinnamyl-4-(2- methoxyphenyl)piperazines, and evaluated their affinities for D2, 5-HT1A, 5-HT2A, and adrenergic (α1) receptors using radioligand-binding assays. In addition, we performed docking analysis using models for the D2 and 5-HT1A receptors. All compounds exhibited low to moderate affinity to 5-HT1A and 5-HT 2A receptors, high affinity to the D2 receptor and large variability in affinities for the α1 receptor. Docking analysis indicated that the binding to D2 and 5-HT1A receptors is based on (i) interaction between protonated N1 of the piperazine ring and various aspartate residues, (ii) hydrogen bonds between various moieties of the ligand and the residues of threonine, serine, histidine or tryptophane, and (iii) edge-to-face interactions of the aromatic ring of the arylpiperazine moiety with phenylalanine or tyrosine residues. Docking data for the D 2 receptor can account for the binding properties obtained in binding assays, suggesting that the model is reliable and robust. However, docking data for the 5-HT1A receptor cannot account for actual binding properties, suggesting that further refinement of the model is required.
- Penjisevic, Jelena,Sukalovic, Vladimir,Andric, Deana,Kostic-Rajacic, Sladjana,Soskic, Vukic,Roglic, Goran
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p. 456 - 465
(2008/12/21)
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- Ruthenium-catalyzed tandem olefin metathesis-oxidations
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(Chemical Equation Presented) The utility of Grubbs' 2nd generation metathesis catalyst has been expanded by the development of two tandem olefin metathesis/oxidation protocols. These ruthenium-catalyzed processes provide cis-diols or α-hydroxy ketones from simple olefinic starting materials.
- Scholte, Andrew A.,Mi, Hyun An,Snapper, Marc L.
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p. 4759 - 4762
(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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- Selenium-catalyzed oxidative halogenation
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Organoselenides catalyze the oxidation of halides by H2O2. Furthermore, these selenides catalyze the transfer of oxidized halogens from N-halosuccinimides to olefins and ketones. Thus, organoselenides catalyze oxidative halogenation reactions including halolactonization, α-halogenation of ketones, and allylic halogenation. The ability of selenium to undergo reversible 2e- oxidation-reduction chemistry facilitates halogenation through selenium-bound halogen intermediates.
- Mellegaard-Waetzig, Shelli R.,Wang, Chao,Tunge, Jon A.
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p. 7191 - 7198
(2007/10/03)
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- Direct halogenation of alcohols and their derivatives with tert-Butyl halides in the ionic liquid [pmIm]Br under sonication conditions - A novel, efficient and green methodology
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A novel halogenating reagent system for direct halogenation of alcohols has been developed. tert-Butyl bromide, chloride and iodide in combination with the ionic liquid [pmIm]Br have been found to convert alcohols into the corresponding bromides, chlorides and iodides under sonication conditions (or heating) in good yields. Although a variety of primary and secondary alcohols participated in this reaction without any difficulty, tertiary alcohols remained inert. Several alcohol derivatives such as OTMS, OTBDMS, OAc, OTS and OTHP are also transformed into the corresponding halides in one-pot fashion by this procedure. A plausible rationale for this transformation is also presented. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Ranu, Brindaban C.,Jana, Ranjan
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p. 755 - 758
(2007/10/03)
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- Selective selenocatalytic allylic chlorination
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Ene-chlorination of olefins by N-chlorosuccinimide is catalyzed by phenylselenenyl chloride. This reaction demonstrates the catalytic conversion of C-H bonds into more reactive C-Cl bonds.
- Tunge, Jon A.,Mellegaard, Shelli R.
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p. 1205 - 1207
(2007/10/03)
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- The formation of medium-sized rings by the intramolecular cyclization of arylnitrenium ions
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The synthesis of an aminodibenzo[a,c]octadiene and an aminodibenzo[a,c]octatriene, guided by molecular mechanics calculations, was effected by the intramolecular cyclization of the corresponding open chain nitrenium ions. Also reported is the predicted failure to synthesize another aminodibenzo[a,c]octadiene using this method.
- Abramovitch, Rudolph A.,Miller, Joseph,De Souza, Antonio J. C.
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p. 6965 - 6967
(2007/10/03)
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- Acetyl chloride-ethanol brings about a remarkably efficient conversion of allyl acetates into allyl chlorides
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AcCl-EtOH transforms primary and secondary allyl acetates into allyl chlorides that retain the olefinic bond in the more stable position. Whereas secondary allyl alcohols also react with almost the same efficacy as the acetates, the reactions of primary allyl alcohols that possess 1, 2-disubstituted alkenes are very slow. The products are isolated in high state of purity simply by removal of the volatiles.
- Yadav, Veejendra K.,Ganesh Babu
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p. 9111 - 9116
(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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- A very mild and chemoselective oxidation of alcohols to carbonyl compounds
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matrixpresented Efficient oxidation of primary alcohols and β-amino alcohols to the corresponding aldehydes and α-amino aldehydes can be carried out at room temperature and in methylene chloride, using trichloroisocyanuric acid in the presence of catalytic TEMPO: aliphatic, benzylic, and allylic alcohols, and β-amino alcohols are rapidly oxidized without no overoxidation to carboxylic acids. Secondary carbinols are slowly oxidized so that the reaction is highly chemoselective.
- De Luca, Lidia,Giacomelli, Giampaolo,Porcheddu, Andrea
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p. 3041 - 3043
(2007/10/03)
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- Pyrrolopyridazine derivatives
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Pyrrolopyridazine derivatives having the general formula. In the above formula, R1 represents a C2-C6alkenyl-group, a halogeno-C2-C6-alkenyl group, a C6-C10 aryl-C2-C6-alkenyl group, a C2-C6 alkynyl group, a C3-C7 cycloalkyl group, a C3-C7 cycloalkyl-C1-C6-alkyl group, a C5-C7 cycloalkenyl-C1-C6-alkyl group or a halogeno-C1-C6-alkyl group; R2 and R3 are the same or different and each represents a hydrogen atom, a C1-C6 alkyl group or a C6-C10 aryl group; R4 represents a hydrogen atom or a C1-C6 alkyl group; R5 represents a C6-C10 aryl group or a 5-10 membered heteroaryl group comtaining heteroatom(s) selected from nitrogen, oxygen and sulfur;
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-
- Phenyl chloro(thionoformate): A new dealkylating agent of tertiary amines
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Phenyl chloro(thionoformate) reacts rapidly with unhindered tertiary aliphatic amines at 20° to give a thiocarbamate and an alkyl chloride. Dialkylcyclohexylamines react surprisingly rapidly to form predominantly cyclohexene. The thiocarbamates are converted into the secondary amine salt by treatment with dimethyl sulfate, followed by hydrolysis with water. Rates of reaction and alkyl group cleavage selectivity in amines were found to be superior or comparable to those previously reported with chloroformates.
- Milan, David S.,Prager, Rolf H.
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p. 841 - 849
(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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- Deamination of trans-2-Methyl- And trans-2-Phenylcyclopropylamines
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The deaminations of trans-2-methyl- and 2-phenylcyclopropylamine hydrochlorides in acetic acid solution have been examined. A major product in each case was an allylic chloride, and the amount of chlorides increased when the chloride ion concentration was increased. With the methyl-substituted amine, increasing the chloride ion concentration changed the major chloride product from crotyl chloride to methallyl chloride. The addition of lithium perchlorate led to a reduction in the amount of chlorides formed. These results indicate that an ion pair is involved in the reaction. The deamination of the related open chain amines gave only small amounts of chlorides. B3LYP/ 6-31G* calculations found cyclopropyldiazonium chloride to prefer to have the chloride ion over the cyclopropyl ring. The transition state was located, and when followed down to products, allyl chloride was found. Similar calculations for the methyl-substituted series led to crotyl chloride from the ion pair with one chloride ion and to methallyl chloride from the ion-triplet with two chloride ions. The deaminations of the corresponding nitrosoureas in basic methanol also were studied. The products were the expected ethers. The addition of azide ion led to azides that were largely formed by initial reaction with the diazonium ion to give a pentazene that lost nitrogen to give the azide. However, some of the azide was formed by an SN2 displacement.
- Wiberg, Kenneth B.,Oesterle, Carmen G.
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p. 7756 - 7762
(2007/10/03)
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- Activation of the silicon-halogen bond by bismuth (III) halides. Halogenation of alcohols: prospective and mechanism
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In the presence of catalytic amount of BiCl3, chloromethylsylanes can be used as chlorinating agents for alcohols, and as chloro-dealkylating agents for silyl ethers and carboxylic and sulfonic esters.The chlorination of (R)-(-)-octan-2-ol and the (R)-(-)-2-mesyloctane by TMSCl gave predominantly the (S)-(+)-2-chlorooctane with inversion of configuration at secondary carbon.According to the class of alcohol, the mechanism involves SN2, SN2' or SN1 processes.This new activation of the Si-Cl bond, probably trough a Si-Cl...BiCl3 interaction gives a hard-soft reagent that can generate a silicenium cation, was also observed with Me3SiBr, BiBr3 and Me3SiI, BiI3 systems.The reaction is also presented as a possible alcoholysis of chlorosilanes, which can lead to siloxanes in non-aqueous conditions. catalysis / halogenation / alcohol / ester / silyl ether / chlorosilane / chlorotrimethylsilane / bromotrimethylsilane / iodotrimethylsilane / siloxane / bismuth (III) halide
- Labrouillere, Mireille,Roux, Christophe Le,Oussaid, Abdelouahad,Gaspard-Iloughmane, Hafida,Dubac, Jacques
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p. 522 - 530
(2007/10/02)
-
- The Reaction between Acyl Halides and Alcohols: Alkyl Halide vs. Ester Formation
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In the reaction between an acyl halide and an alcohol the thermodynamically favoured products are the free carboxylic acid and the alkyl halide.The initial reaction is, generally, the formation of an ester and HHal.When the alcohol is very prone to yield an alkyl cation upon protonation by HHal, formed H2O exhibited a superior reactivity and competed successfully with the alcohol for the acyl halide making, therefore, ester formation practically confined to a triggering role.But, in those cases where the cation is less easily formed, ester formation was favoured and, consequently, became the necessary elementary step towards alkyl halide formation.Tis final product, on the other hand, might be extremely slow to form in an SN2 reaction between the protonated ester function and the halide ion.In these instances, therefore, as well as in the cases when a basic solvent competes for the proton of HHal, the ester is the final product.A notable exception of the situation above outlined, is given by α-hydroxy-α-phenylbenzeneacetic acid (2y), which appears to undergo direct chlorine-hydroxyl interchange through a quaternary intermediate (E), in the end collapsing to α-chloro-α-phenyl-benzeneacetic acid (4y).Different systems were compared using CH2Cl2 as a solvent under strictly similar conditions.Some 28 different substrates were tested for reaction with AcCl (1a), whereas the action of eight acyl halides (a) against (RS)-α-methylbenzenemethanol (2n) and α-phenylbenzenemethanol (2p), as well as the effect of five different solvents on the reaction between two alcohols (2p and 2-methyl-2-propanol, 2c) with 1a, were observed.
- Strazzolini, Paolo,Giumanini, Angelo G.,Verardo, Giancarlo
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p. 217 - 254
(2007/10/02)
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- TRANSITION METHAL-CATALYZED SUBSTITUTION REACTION OF ALLYLIC PHOSPHATES WITH GRIGNARD REAGENTS
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SN2-selective Grignard coupling with primary allylic diphenylphosphates was successfully achieved using Ni or Fe catalyst.In sharp contrast, a catalytic amount of CuCN*2LiCl promoted a SN2'-selective coupling reaction.In the presence of the copper catalyst, stereochemically homogeneous γ-disubstituted allyl Grignard reagents reacted at the less substituted allylic terminus (α-position) with an allylic diphenylphosphate selectively without losing the double bond geometry.
- Yanagisawa, Akira,Nomura, Nobuyoshi,Yamamoto, Hisashi
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p. 6017 - 6028
(2007/10/02)
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- Stereoselective Synthesis of α-(Chloromethylene)-γ-butyrolactone Derivatives from Acyclic Allylic 2-Alkynoates
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α-Methylene-γ-butyrolactones have been constructed by a bis(benzonitrile)palladium dichloride catalyzed cyclization reaction of the easily available acyclic 2'-alkenyl 2-alkynoates in the presence of CuCl2.A mechanism involving a stereoselective chloropalladation in the presence of CuCl2, followed by intramolecular insertion of a carbon-carbon double bond to the carbon-palladium bond, and subsequent CuCl2-mediated formation of a new carbon-chlorine bond is briefly discussed.
- Ma, Shengming,Lu, Xiyan
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p. 1245 - 1250
(2007/10/02)
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- Oxovanadium-induced oxidative desilylation of allylic and benzylic silanes
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Cinnamyltrimethylsilane underwent desilylation via one-electron oxidation with VO(OEt)Cl2, which was applied to the cross-coupling with the less oxidizable allylic silanes to give the corresponding 1,5-hexadienes. Chlorination or aromatization
- Fujii, Takashi,Hirao, Toshikazu,Ohshiro, Yoshiki
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p. 5601 - 5604
(2007/10/02)
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- Asymmetric Oxidation of Simple Selenides to Selenoxides in High Enantiopurity. Stereochemical Aspects of the Allyl Selenoxide/Allyl Selenenate Rearrangement
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For the first time simple alkyl aryl selenoxides of high enantiomeric purity (90-95percent ee) and well-defined stereochemistry are available via the asymmetric oxidation of selenides using (+)- or (-)-N-(phenylsulfonyl)-(3,3-dichlorocamphoryl)oxaziridine heptane-2,3'-oxaziridine>>>.These nonracemic selenoxides, which are more stable in solution than in the solid state, exhibit high configurational stability as long as acid and moisture are excluded.Complete racemization occurs within minutes on addition of trace amounts of acid and water.The asymmetric oxidation of (E)- and (Z)-aryl cinnamyl selenides 11 and 12 with oxaziridine (+)-4 affords optically active 1-phenyl allyl alcohol (15) via a concerted sigmatropic selenoxide-selenenate rearrangement.The extent of 1->3 chirality transfer (41-62percent ee) as well as the endo/exo transition state geometry is highly dependent on the structure of the allylic selenide.
- Davis, Franklin A.,Reddy, R. Thimma
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p. 2599 - 2606
(2007/10/02)
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- Imidazolidinones as brain activators
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This invention relates to imidazolidinone compounds of the formula STR1 wherein Q is methylene group or a single bond: R is a heterocyclic group selected from the group consisting of pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl and 1,3-thiazolyl which may be unsubstituted or with a substituent selected from the group consisting of lower alkyl, lower alkoxy and halogen atom, wherein R is bonded to Q or, when Q is a single bond, to the imidazolidinone ring, through the carbon atom of R; the ring A is an unsubstituted phenyl or a substituted phenyl having 1 or 2 substituent(s) selected from the group consisting of lower alkyl, lower alkoxy, halogen, lower alkylthio, trihalogeno-lower alkyl and nitro; Y is vinylene group or ethynylene; m is a integer from 1 to 6 and n is 0, 1 or 2, or a pharmacetically acceptable salt thereof. These compounds aer useful as cerebral activators, anti-depressants and nootropic drugs.
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- REGIOSPECIFIC AND STEREOSPECIFIC SUBSTITUTION OF HYDROXYL IN ALIPHATIC ALCOHOLS BY HALOGEN
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A new system containing triphenylphosphine and trichloro- and tribromoacetic ester makes it possible to substitute the hydroxyl group in alcohols by halogen.Regiospecific and stereospecific substitution of the hydroxyl by the halogen takes place as a result of the reaction of primary and secondary aliphatic alcohols and of 2-alkenols, susceptible to isomerization processes, with this system.
- Matveeva, E. D.,Kurts, A. L.,Yalovskaya, A. I.,Nikishova, N. G.,Bundel', Yu. G.
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p. 642 - 646
(2007/10/02)
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- Phenylselenium Trichloride in Organic Synthesis. Reaction with Unsaturated Compounds. Preparation of Vinylic Chlorides via Selenoxide Elimination
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Phenylselenium trichloride, PhSeCl3, was reacted with a number olefinic compounds to produce (β-chloroalkyl)phenylselenium dichlorides.The addition was anti stereospecific and irreversible.The presence of an oxygen substituent (acyloxy or aryloxy group) in the allylic position of the olefin directed the attack of PhSeCl3 to occur regiospecifically anti-Markovnikov to give a (β-acyloxy/aryloxy-β'-chloroalkyl)phenylselenium dichloride.When the (β-chloroalkyl)phenylselenium dichlorides were treated in methylene chloride with aqueous sodium hydrogen carbonate, the selenium dichloride moiety was readily hydrolyzed to a selenoxide, which underwent the usual selenoxide elimination reaction to produce an allylic or a vinylic chloride.Symmetrical olefins containing no allylic hydrogens were converted to vinylic chlorides with retention of olefin geometry.Olefins containing a directing oxygen substituent in the allylic position afforded vinylic chlorides where the vinylic halogen atom was oriented 1,3 to the oxygen substituent (E/Z mixture).Other olefins afforded mixtures of allylic and vinylic halides in varying proportions.The reaction of phenyselenium tribromide, PhSeBr3, with some olefinic compounds was also investigated.This material showed the same stereo- and regiochemical behavior as PhSeCl3 in its addition reactions.However, the adducts were not useful for the preparation of vinylic or allylic bromides by using the hydrolytic selenoxide elimination reaction.
- Engman, Lars
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p. 4086 - 4094
(2007/10/02)
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- Preparation of Alkyl Chlorides, Acid Chlorides, and Amides Using Polymer-Supported Phosphines and Carbon Tetrachloride: Mechanism of These Reactions
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Alcohols and thiols were converted into alkyl chlorides, carboxylic acids were converted into acid chlorides, and mixtures of carboxylic acids and amines were converted into amides by reaction with carbon tetrachloride and 1percent cross-linked polystyrenes containing phosphine residues.Some of these conversions were also effected by using a linear polymer containing phosphine residues.The reactions proceed in high yield, and isolation of the products is facilitated by the ready removal of all the polymer-supported species.The mechanism of the reactions between triphenylphosphine, carbon tetrachloride, and alcohols is complex, but the polymer-supported reactions appear to follow analogous pathways to the low molecular weight reactions as judged by the yields of chloroform and the number of equivalents of phosphine consumed per mole of alkyl chloride produced.The mechanism requires polymer-supported groups reacting together.The slow step in the reactions appears to be the generation of the chlorinating species.The polymer-supported reactions are faster than those using triphenylphosphine or 4-(diphenylphosphinyl)isopropylbenzene.It is suggested that this is due to a microenvironmental effect.
- Harrison, Charles R.,Hodge, Philip,Hunt, Barry J.,Khoshdel, Ezzatollah,Richardson, Graham
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p. 3721 - 3728
(2007/10/02)
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- Process for production of 2,6-di-tert-alkenyl phenols
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There is disclosed a process for the production of 2,6-di-tert-alkyl-4-alkenyl phenols wherein the improvement comprises the reaction of a 2,6-di-tert-alkyl phenol with an allyl halide to yield the 2,6-di-tert-alkyl-4-alkenyl phenol through the use of a triphase or polymer bound catalyst.
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