- Synthesis of oxidized thioxanthene-type base amplifiers and their application to photoreactive materials
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We propose base amplifiers (BAs) that are autocatalytically decomposed into base molecules by a small amount of trigger base molecules from photobase generators. We report here novel BAs having oxidized thioxanthene skeletons. It is confirmed that they are decomposed autocatalytically in solution or polymer matrix. They are applied to UV curing systems to improve their photosensitivity.
- Arimitsu, Koji,Kitamura, Hiroshi,Mizuochi, Ryuta,Furutani, Masahiro
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Read Online
- Generation and direct observation of the thioxanthenyl and N-methyl acridinyl anions; A family of stable, paratropic, "4N" π-excessives
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The title, thermally stable, heterocarbanions (2a, 2b) were generated upon respective exposure of conjugate acids 4(a,b) to a KNH2/liq. NH3 system and were shown (NMR) to possess (2a more than 2b) distinct elements of paratropicity.
- Anastassiou,Kasmai,Saadein
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Read Online
- Formation and Disproportionation of Xanthenols to Xanthenes and Xanthones and Their Use in Synthesis
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A facile and versatile strategy employing TiCl4-mediated cyclization followed by a Cannizzaro reaction has been developed for the synthesis of various xanthene derivatives. The reaction proceeded smoothly to afford both xanthenes/xanthones or their sulfur derivatives and tolerated a wide range of electronically diverse substrates. Using this methodology, pranoprofen was synthesized in three steps in 59% overall yield from commercially available starting materials.
- Shi, Zeyu,Chen, Si,Xiao, Qiong,Yin, Dali
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p. 3334 - 3343
(2021/02/05)
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- Method for reducing carbonyl reduction to methylene under illumination
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The invention belongs to the technical field of organic chemical synthesis. The method comprises the following steps: (1) mixing the carbonyl compound and the amine compound in a solvent, reacting 3 - 6 under the illumination of 380 - 456 nm, the reaction system is low in toxicity, high in atom utilization rate 12 - 24h. and production efficiency, safe and controllable in reaction process and capable of simplifying the operation in the preparation and production process. At the same time, the residue toxicity of the reaction is minimized, the pollution caused by the production process to the environment is reduced, and the steps and operations of removing residues after the reaction are simplified. In addition, the reactant feedstock is readily available. The reactant does not need additional modification before the reaction, can be directly used for preparing production, simplifies the operation steps, and shortens the reaction route. The production cost is obviously reduced.
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Paragraph 0033-0038; 0140-0144
(2021/09/29)
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- High-Fidelity Dimerization of Xanthenyl Radicals and Dynamic Qualities of a Congested Ethane: Diethyl Dixanthenyl-9,9′-Dicarboxylate
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Exploration of the sterically-congested ethane diethyl dixanthenyl-9,9′-dicarboxylate has revealed the dynamic behavior arising from its congested C?C bond. Interlocking ‘geared’ substituents and favorable dispersion interactions around this bond result in a conformational preference for partially cofacial xanthene moieties both in solid state and as dilute solutions. The weak, centrally located C?C bond is 1.628 ? long and permits selective thermolysis to yield two carbon-centered ethyl xanthenyl-9-carboxylate radicals, which dimerize with high fidelity into the original sterically-congested ethane. Recombination of the radicals into this symmetrical head-to-head dimer is highly reproducible – by observing the equilibrium, the bond dissociation enthalpy was calculated to be 20.4 kcal ? mol?1. The substituents around the central carbon provide insufficient stabilization against oxygen, which consumes the radicals and unbalances the dimer-radical equilibrium.
- Dubrawski, Zachary,Gelfand, Benjamin S.,Hogan, David T.,Sutherland, Todd C.
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supporting information
(2021/12/23)
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- Access to Cyanoimines Enabled by Dual Photoredox/Copper-Catalyzed Cyanation of O-Acyl Oximes
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An efficient strategy for the synthesis of pharmaceutically important and synthetically useful cyanoimines, as well as cyanamides, has been described. This strategy is enabled by dual photoredox/copper-catalyzed cyanation of O-acyl oximes or O-acyl hydroxamides. This state of the art protocol for cyanoimines and cyanamides features readily available starting materials, mild reaction conditions, good functional group tolerance, and operational simplicity. The resultant cyanoimines can be transformed into structurally diverse and functionally important N-containing heterocycles.
- Wei, Ziyan,Yu, Shouyun,Zhang, Ai Hua,Zhang, Hao
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supporting information
p. 7315 - 7320
(2020/10/02)
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- Uncatalyzed Oxidative C?H Amination of 9,10-Dihydro-9-Heteroanthracenes: A Mechanistic Study
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A new method for the one-step C?H amination of xanthene and thioxanthene with sulfonamides is reported, without the need for any metal catalyst. A benzoquinone was employed as a hydride (or two-electron and one-proton) acceptor. Moreover, a previously unknown and uncatalyzed reaction between iminoiodanes and xanthene, thioxanthene and dihydroacridines (9,10-dihydro-9-heteroanthracenes or dihydroheteroanthracenes) is disclosed. The reactions proceed through hydride transfer from the heteroarene substrate to the iminoiodane or benzoquinone, followed by conjugate addition of the sulfonamide to the oxidized heteroaromatic compounds. These findings may have important mechanistic implications for metal-catalyzed C?H amination processes involving nitrene transfer from iminoiodanes to dihydroheteroanthracenes. Due to the weak C?H bond, xanthene is an often-employed substrate in mechanistic studies of C?H amination reactions, which are generally proposed to proceed via metal-catalyzed nitrene insertion, especially for reactions involving nitrene or imido complexes that are less reactive (i.e., less strongly oxidizing). However, these substrates clearly undergo non-catalyzed (proton-coupled) redox coupling with amines, thus providing alternative pathways to the widely assumed metal-catalyzed pathways.
- van Leest, Nicolaas P.,Grooten, Lars,van der Vlugt, Jarl Ivar,de Bruin, Bas
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supporting information
p. 5987 - 5993
(2019/04/03)
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- Visible-light induced enhancement in the multi-catalytic activity of sulfated carbon dots for aerobic carbon-carbon bond formation
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The development of carbonaceous materials as metal-free catalysts integrating different types of catalysis in a single system represents a significant advance in cascade/tandem organic synthesis. Zero-dimensional carbon dots with tuneable optical properties and easily modifiable surface functionalities can be harnessed as a carbocatalyst for merging photooxidation and acid-catalyzed reactions in one pot. Herein, we explore carbon dots decorated with hydrogen sulfate groups as a photocatalyst for the dehydrogenative cross-coupling of xanthenes with ketones, arenes and 1,3-dicarbonyl compounds that showed high efficiency and selectivity under visible-light irradiation. The sulphated carbon dots demonstrate dual catalytic properties, wherein they induced the rapid photooxidation of xanthenes in the presence of molecular oxygen to form a hydroperoxy intermediate followed by coupling of nucleophiles catalysed by the acidic surface functional groups. The methodology represents an operationally simple pathway for the generation of C-C coupling products in a short reaction time with wide substrate scopes under mild conditions. The catalyst is easily separable and can be reused over multiple cycles with good efficiency.
- Sarma, Daisy,Majumdar, Biju,Sarma, Tridib K.
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supporting information
p. 6717 - 6726
(2019/12/26)
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- Electrochemical Hydrogenation with Gaseous Ammonia
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As a carbon-free and sustainable fuel, ammonia serves as high-energy-density hydrogen-storage material. It is important to develop new reactions able to utilize ammonia as a hydrogen source directly. Herein, we report an electrochemical hydrogenation of alkenes, alkynes, and ketones using ammonia as the hydrogen source and carbon electrodes. A variety of heterocycles and functional groups, including for example sulfide, benzyl, benzyl carbamate, and allyl carbamate were well tolerated. Fast stepwise electron transfer and proton transfer processes were proposed to account for the transformation.
- Li, Jin,He, Lingfeng,Liu, Xu,Cheng, Xu,Li, Guigen
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supporting information
p. 1759 - 1763
(2019/01/16)
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- Cu(ii)-catalyzed sulfide construction: both aryl groups utilization of intermolecular and intramolecular diaryliodonium salt
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A sulfur-iodine exchange protocol of diaryliodonium salts with inorganic sulfur salt was developed. Both aryl groups in the diaryliodonium salt were fully exerted in this transformation. Five- to eight-membered sulfur-containing heterocycles were achieved. Note that [1]benzothieno-[3,2-b][1]benzothiophene (BTBT) (an organic field-effect transistor (OFET) material) and Zaltoprofen were efficiently established through this method.
- Wang, Ming,Wei, Jianpeng,Fan, Qiaoling,Jiang, Xuefeng
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supporting information
p. 2918 - 2921
(2017/03/15)
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- Diaryl ring fused sulfides and diaryl ring fused selenides, and synthesis method and application thereof
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The invention discloses a synthesis method of diaryl ring fused sulfides represented by formula (B) and diaryl ring fused selenides represented by formula (C). The method is characterized in that a reaction of a reaction raw material high-iodine salt is carried out in dimethyl sulfoxide under the action of an inorganic sulfuration reagent or selenylation reagent and an alkali at 60-100 DEG C to obtain the diaryl ring fused sulfides and the diaryl ring fused selenides. Sulfur or selenium is introduced in the later stage in the presence of a nonmetal catalyst, so poisoning of sulfur to a metal catalyst in the early stage reaction is avoided; the above inorganic sulfur source is nontoxic and odorless; and two aryl groups in the high-iodine salt are fully used, so the atom economy and the greenness of the method are fully shown. The diaryl ring fused sulfides and the diaryl ring fused selenides prepared through the method can be applied to synthesize photoelectric materials BTBT and BTBS.
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Paragraph 0093; 0094; 0095; 0096
(2017/06/20)
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- Diaryl thioether compound, and synthetic method and application thereof
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The invention discloses a diaryl thioether compound, and a synthetic method and an application thereof. Various diaryl thioether compounds can be obtained through a reaction of a reaction raw material high iodine salt in dimethyl sulfoxide at 60-100DEG C under the action of an odorless sulfuration reagent, an alkali, a metal catalyst and a ligand for 3-12h. Sulfur is introduced in the later stage, so poisoning of sulfur to the metal catalyst and incompatibility of an oxidant in the early stage reaction are avoided; the above inorganic sulfur source is nontoxic and odorless; and two aryl groups in the high iodine salt are fully used, so the atom economy of the method is fully shown. The diaryl thioether compound prepared through the method can be further used to synthesize a photoelectric material BTBT and an anti-inflammatory drug zaltoprofen.
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Paragraph 0160-0164
(2018/02/04)
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- N-Benzyldithiocarbamate Salts as Sulfur Sources to Access Tricyclic Thioheterocycles Mediated by Copper Species
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Using an easily prepared triethylammonium N-benzyldithiocarbamate salt as a sulfur source, a dual C?S functionalization of cyclic diaryliodoniums to form tricyclic thioheterocycles is realized. Our method uses the readily available copper sulfate to accelerate the chemical transformation under mild conditions. A broad range of cyclic diaryliodoniums with a ring size from 5- to 7-membered can be employed to gain a quick access to tricyclic thioheterocycles including dibenzothiophenes, thioxanthenes, and phenoxathiines. (Figure presented.).
- Luo, Bingling,Cui, Qingbin,Luo, Hongwen,Hu, Yumin,Huang, Peng,Wen, Shijun
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supporting information
p. 2733 - 2738
(2016/09/13)
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- Transition-Metal-Free Diarylannulated Sulfide and Selenide Construction via Radical/Anion-Mediated Sulfur-Iodine and Selenium-Iodine Exchange
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A facile, straightforward protocol was established for diarylannulated sulfide and selenide construction through S-I and Se-I exchange without transition metal assistance. Elemental sulfur and selenium served as the chalcogen source. Diarylannulated sulfides were systematically achieved from a five- to eight-membered ring. A trisulfur radical anion was demonstrated as the initiator for this radical process via electron paramagnetic resonance (EPR) study. OFET molecules [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and [1]benzothieno[3,2-b][1]benzoselenophene (BTBS) were efficiently established.
- Wang, Ming,Fan, Qiaoling,Jiang, Xuefeng
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supporting information
p. 5756 - 5759
(2016/11/17)
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- Synthesis of spirocyclic diarylfluorenes by one-pot twofold SNAr reactions of diaryl sulfones with diarylmethanes
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Treatment of dibenzothiophene dioxides with cyclic diarylmethanes in the presence of KN(SiMe3)2 results in the formation of fluorene-based spirocyclic tetraarylmethanes in a single operation. The transformation would proceed via an intermolecular SNAr reaction of the dioxides with cyclic diarylmethylpotassium followed by intramolecular SNAr cyclization. This straightforward strategy provides a wide range of spirocyclic diarylfluorenes including unusual ones that are otherwise difficult to synthesize.
- Bhanuchandra,Yorimitsu, Hideki,Osuka, Atsuhiro
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supporting information
p. 384 - 387
(2016/02/19)
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- Oxidative C-H bond functionalization and ring expansion with TMSCHN2: A copper(I)-catalyzed approach to dibenzoxepines and dibenzoazepines
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Tricyclic dibenzoxepines and dibenzazepines are important therapeutic agents for the pharmaceutical industry and academic research. However, their syntheses are generally rather tedious, requiring several steps that involve a Wagner-Meerwein-type rearrangement under harsh conditions. Herein, we present the first copper(I)-catalyzed oxidative C-H bond functionalization and ring expansion with TMSCHN2 to yield these important derivatives in a facile and straightforward way. Cut a long story short: Tricyclic dibenzoxepines and dibenzazepines are important therapeutic agents for pharmaceuticals, but their syntheses are generally rather tedious. A copper(I)-catalyzed oxidative C-H bond functionalization and ring expansion sequence with TMSCHN2 has been developed to yield these important derivatives in a facile and straightforward way.
- Stopka, Tobias,Marzo, Leyre,Zurro, Mercedes,Janich, Simon,Würthwein, Ernst-Ulrich,Daniliuc, Constantin G.,Alemán, José,Manche?o, Olga García
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supporting information
p. 5049 - 5053
(2015/04/27)
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- Synthesis and bio-evaluation of phenothiazine derivatives as new anti-tuberculosis agents
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Abstract Two series of phenothiazine derivatives were designed and synthesized. All compounds were tested for anti-tuberculosis activities against Mycobacterium tuberculosis H37RV. In comparison with mother compound of chlorpromazine, compound 6e shows promising anti-tuberculosis activity and much less mammalian cell cytotoxicity, compound 6e merits to be further explored as new anti-tuberculosis agents.
- He, Chun-Xian,Meng, Hui,Zhang, Xiang,Cui, Hua-Qing,Yin, Da-Li
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supporting information
p. 951 - 954
(2015/08/18)
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- A classical but new kinetic equation for hydride transfer reactions
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A classical but new kinetic equation to estimate activation energies of various hydride transfer reactions was developed according to transition state theory using the Morse-type free energy curves of hydride donors to release a hydride anion and hydride acceptors to capture a hydride anion and by which the activation energies of 187 typical hydride self-exchange reactions and more than thirty thousand hydride cross transfer reactions in acetonitrile were safely estimated in this work. Since the development of the kinetic equation is only on the basis of the related chemical bond changes of the hydride transfer reactants, the kinetic equation should be also suitable for proton transfer reactions, hydrogen atom transfer reactions and all the other chemical reactions involved with breaking and formation of chemical bonds. One of the most important contributions of this work is to have achieved the perfect unity of the kinetic equation and thermodynamic equation for hydride transfer reactions. The Royal Society of Chemistry.
- Zhu, Xiao-Qing,Deng, Fei-Huang,Yang, Jin-Dong,Li, Xiu-Tao,Chen, Qiang,Lei, Nan-Ping,Meng, Fan-Kun,Zhao, Xiao-Peng,Han, Su-Hui,Hao, Er-Jun,Mu, Yuan-Yuan
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p. 6071 - 6089
(2013/09/12)
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- Synthesis of dihydrodibenzo[b,f]furo[2,3-d]oxepins and related reactions
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Nine dihydrodibenzo[b,f]furo[2,3-d]oxepin derivatives were synthesized by the Mn(III)-based oxidative addition of dibenz[b,f]oxepins at C10-C11 with acetic anhydride, acetylacetone, dialkyl malonates, and malonamide. Oxidative ring-expansion of methyl hydrogen thioxanthenylmalonate with manganese(III) acetate did not give the desired dibenzo[b,f]thiepincarboxylate but produced 2-acetoxy-2-(thioxanthen-9-yl)acetate and thioxanthone.
- Maemura, Yasunobu,Tanoue, Yuka,Nishino, Hiroshi
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p. 2491 - 2503,13
(2020/08/24)
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- CHEMILUMINESCENCE COMPOSITIONS AND METHODS
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Methods and compositions for generating chemiluminescence on reaction with a peroxidase enzyme are provided as well as compounds to be used in the methods and compositions. The compounds have a C-C double bond substituted at one carbon with two oxygen or sulfur atom-containing groups. The compositions contain the double bond-containing compound and a peroxide in an aqueous solution. Additional components which can be included in the compositions are peroxidase activity enhancers, nonionic surfactants or cationic surfactants to improve detection sensitivity of the peroxidase. The chemiluminescent methods and compositions are useful in assays for peroxidase enzymes and in assays employing enzyme-labeled specific binding pairs.
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- Nitrous oxide oxidation catalyzed by ruthenium porphyrin complex
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Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of dioxoruthenium tetramesitylporphyrin complex (Ru(tmp)(O)2). A variety of olefins, secondary alcohols, and benzyl alcohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of 9,10-dihydroanthracene derivatives, the competitive reactions affording anthraquinones and anthracenes could be regulated by the reaction conditions. At a high temperature (200°C), anthraquinones were selectively produced, while the anthracenes were selectively produced by the addition of sulfuric acid.
- Tanaka, Hirotaka,Hashimoto, Kentaro,Suzuki, Kyosuke,Kitaichi, Yasunori,Sato, Mitsuo,Ikeno, Taketo,Yamada, Tohru
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p. 1905 - 1914
(2007/10/03)
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- Novel derivatives and analogues of galanthamin
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New compounds of general formula I 1
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- Spirotricyclic substituted azacycloalkane derivatives and uses thereof
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Spirotricyclic azacycloalkyl compounds and pharmaceutically acceptable salts thereof are disclosed. The synthesis of these compounds is also described. One application of these compounds, which are alpha 1a adrenergic receptor antagonists, is in the treatment of benign prostatic hyperplasia. These compounds are selective in their ability to relax smooth muscle tissue enriched in the alpha 1a receptor subtype without at the same time inducing hypotension. One such tissue is found surrounding the urethral lining. Therefore, one utility of the instant compounds is to provide acute relief to males suffering from benign prostatic hyperplasia, by permitting less hindered urine flow. Another utility of the instant compounds is provided by combination with a human 5-alpha reductase inhibitory compound, such that both acute and chronic relief from the effects of benign prostatic hyperplasia can be achieved.
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- NITROGEN-CONTAINING HETEROCYCLIC COMPOUNDS AND BENAMIDE COMPOUNDS AND DRUGS CONTAINING THE SAME
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Disclosed are compounds represented by formula (I) which have triglyceride biosynthesis inhibitory activity in the liver and inhibitory activity against the secretion of apolipoprotein B-containing lipoprotein from the liver and particularly have excellent inhibitory activity against the secretion of apolipoprotein B-containing lipoprotein, are free from side effect of accumulation of lipids in the liver, and are useful for the treatment and prevention of hyperlipidemia and arteriosclerotic diseases. In formula (I), R1 and R2 represent alkyl, alkoxy, cycloalkyl, phenyl, alkenyl, alkynyl, or a five- or six-membered saturated or unsaturated heterocyclic ring, or R1 and R2, together with a nitrogen atom to which R1 and R2 are attached, may form a ring; R3 and R4 represent a hydrogen atom, alkyl, a halogen atom, hydroxyl, nitrile, alkoxycarbonyl, alkoxy, or carboxyl; or R2 and R3 may be attached to each other to form -(CH2)m-, -N=CH-, -CH=N-, or -(C1-6 alkyl)C=N-; A, D, E, and G each represent a carbon atom, or any one of A, D, E, and G represents a nitrogen atom with the other three each representing a carbon atom; Q represents a nitrogen atom or a carbon atom; Y represents a group represented by formula (II) wherein X represents a hydrogen atom, group -C(=O)N(R5)R6 or group -C(=O)OR7, R8 is absent or represents a bond, an oxygen atom, a sulfur atom, -SO2-, -SO-, -CH2-CH2-, or - CH=CH-, and R9 and R10 represent a hydrogen atom, alkyl, alkoxy, a halogen atom, or hydroxyl; and Z represents - (CH2)n-, -O-(CH2)i-, or -C(=O)NH-(CH2)i-.
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- SAR studies on the potent and selective muscarinic antagonist 2- ethylthio-2,2-diphenylacetic acid N,N-diethylaminoethyl ester
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Molecular modification of the potent and selective muscarinic antagonist 2-ethylthio-2,2-diphenylacetic acid N,N-diethylaminoethyl ester was performed in order to identify M2 selective antagonists able to cross the blood brain barrier and potentially useful in the treatment of Alzheimer's disease. Modifications included substitution or hydrogenation of one of the phenyl rings as well as their incorporation in a tricyclic system. In general the changes introduced were detrimental for both affinity and selectivity. Only a modest M2 selectivity is present in some compounds that, on the other hand, carry a quaternary ammonium group which precludes their penetration into the brain.
- Scapecchi, Serena,Angeli, Piero,Dei, Silvia,Ghelardini, Carla,Gualtieri, Fulvio,Marucci, Gabriella,Paparelli, Fiorella,Romanelli, M. Novella,Teodori, Elisabetta
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p. 122 - 128
(2007/10/03)
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- An effective synthesis of fused cyclic thiopyrans and pyrans by molybdenum(VI) sulfide catalyzed reduction of the corresponding thiopyranones and pyranones
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The synthesis of fused cyclic dihydrothiopyrans 2a-c from dihydrothiopyranones 1a-c and thiopyrans 2d-f from thiopyranones 1d-f by catalytic reduction over molybdenum(VI) sulfide (MoS3) has been studied. The hydrogenolysis of the carbonyl group of 1a-f over MoS3 catalyst proceeded selectively to give the corresponding 2a-f in high yields. Neither alcohols nor olefins were not detected in the products. The method was also applied successfully to the synthesis of dihydropyran 2h and pyran 2g from dihydropyranone 1h and pyranone 1g.
- Takido,Takagi,Itabashi
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p. 687 - 690
(2007/10/02)
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- Gas phase generation and cyclisation reactions of some o-substituted phenyl radicals
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Flash vacuum pyrolysis of the allyl esters 2 (X=O, S, CH2, CO) at 900°C (10-2 Torr) gives dibenzofurans, dibenzothiophenes, fluorenes, and fluorenones respectively as the major products. The mechanism involves the phenyl radical intermediates 1 which equilibrate by intramolecular hydrogen transfer via six-membered transition states, prior to cyclisation.
- Cadogan,Hutchison,McNab
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p. 7747 - 7762
(2007/10/02)
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- Two-Dimensional NMR Studies of 2-Substuituted Thioxanthene Sulfoxides
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2-Fluoro-, 2-chloro-, 2-bromo-, 2-methyl-, and 2-methoxythioxanthene have been prepared by borane reduction of the corresponding thioxanthone.The corresponding sulfoxides were prepared by m-chloroperoxybenzoic acid oxidation of these sulfides.Proton and carbon chemical shifts have been assigned to these thioxanthene sulfoxides with the aid of LROCSCM and SROCSCM experiments.Carbon chemical shifts in the unsubstituted rings occur at approximately 125 ppm (C5); 128 ppm (C6); 130 ppm (C7); 128 ppm (C8); and 36 ppm (C9).The methylene protons appears as AB doublets at approximately 4.2 and 3.8 ppm.All sulfoxides have the same, pseudo- equatorial geometry.
- Mlotkowska, B. L.,Cushman, James A.,Harwood, J.,Lam, W. W.,Ternay, A. L.
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p. 731 - 736
(2007/10/02)
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- Thermal Interconversion and Cyclisation Reactions of 2-(Arylthio)benzyl Radicals and 2-(Benzyl)thiophenoxyl Radicals
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Generation of the title radicals by flash vacuum pyrolysis leads to thioxanthene(s) as the sole significant product(s).Cyclisation takes place via an intermediate spirodienyl radical .
- Cadogan, J. I. G.,Hutchison, H. Susan,McNab, Hamish
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p. 2875 - 2880
(2007/10/02)
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- POTENTIAL ANTIHISTAMINE AGENTS: 4-(6,11-DIHYDRODIBENZOTHIEPIN-11-YLIDENE)-1-METHYLTETRAHYDROTHIOPYRANIUM IODIDE AND SIMILAR SULFONIUM SALTS DERIVED FROM RELATED TRICYCLIC SYSTEMS
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Thioxanthone, 10,11-dihydrodibenzocyclohepten-5-one, dibenzothiepin-11(6H)-one, its 2-methyl derivative, and thieno-2-benzothiepin-4(9H)-one were reacted with 4-tetrahydrothiopyranylmagnesium bromide and the obtained tertiary alcohols IVabc, VIc, and XIX were dehydrated to the olefinic sulfides IXabc, Xc, and XXI.Addition of methyl iodide afforded the title compounds XIabc, XIIc, and XXII.The Grignard reactions were accompanied by the 1,6-addition giving the ketones XVI-XVIII as by-products.The reductive properties of tetrahydrothiopyranylmagnesium bromide were most striking in the case of reaction with 2-chlorothioxanthone; the isolation of thioxanthene and thioxanthone showed that nuclear dehalogenation took also place.Reactions of 11-chloro-6,11-dihydrodibenzothiepin and benzhydryl chloride with tetrahydrothiopyran-4-ol gave the sulfides XXV and XXVIII; whereas the latter reacted with methyl iodide under the formation of sulfonium salt XXIX, the former was cleaved and gave 4-hydroxyl-1-methyltetrahydrothiopyranium iodide (XXVI).The sulfonium salts are free of the central effects but their antihistamine activity is rather low.
- Polivka, Zdenek,Holubek, Jiri,Budesinsky, Milos,Matousova, Oluse,Svatek, Emil,et al.
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p. 2758 - 2774
(2007/10/02)
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- Zn/OH- REDUCTIONS OF ORGANIC COMPOUNDS IN DIMETHYLSULFOXIDE ; A NEW SIMPLE METHOD OF PREPARING RADICAL ANIONS
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A new method of preparing radical anions from a variety of organic substrates is proposed that involves the use of Zn/KOH in DMSO as electron source.
- Handoo, Kishan L.,Gadru, Kanchan
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p. 1371 - 1372
(2007/10/02)
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- Reduction of Aromatic Ketones or Thioketones with Phenylphosphine
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Reactions of certain aromatic ketones or thioketones with phenylphosphine and subsequent addition of diethyl disulfide gave the reduction products of the ketones and S,S-diethyl phenylphosphonodithioate or S,S-diethyl phenylphosphonotrithioate.A possible intermediate of the phosphine moiety was suggested to be phenylphosphinylidene or phenylphosphinothioylidene .The reduction of 10,10'-bianthrone and Δ10,10'-bianthrone resulted in the cleavage of the carbon-carbon single and double bonds and the reduction of the carbonyl groups, respectively.
- Tamano, Michiko,Koketsu, Jugo
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p. 2577 - 2580
(2007/10/02)
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- Process for the synthesis of peptides utilizing thioxanthylmethyloxycarbonyl dioxides
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A composition of the formula: STR1 wherein X is lower alkyl, and Z is an amino acid a peptide residue or a good leaving group, the composition is adaptable as a blocking or protecting group for an amine composition useful in peptide synthesis and a method of protecting an amino group of an organic molecule during a reaction which modifies a portion of the molecule other than the protected amino group.
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- REACTIONS OF 4,4'-DISUBSTITUTED DIPHENYL SULFIDES WITH CHLOROACETYL CHLORIDE AND ALUMINIUM CHLORIDE
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Reactions of 4,4'-dihalogenodiphenyl sulfides IIIa - IIIc with chloroacetyl chloride and aluminium chloride afforded the enol forms of 2,8-dihalogeno-11-(chloroacetyl)dibenzothiepin-10(11H)-ones IVa - IVc.A similar reaction of di(4-methylphenyl)sulfide (IIId) resulted in 9-(chloromethylene)-2,7-dimethylthioxanthene (Vd) as the main product.Substitution reactions of IVa with piperidine and 1-methylpiperazine gave compounds VI a VII with the unchanged chelate system of the starting substance.A stepwise methylation of (2-phenylthiophenyl)acetonitrile resulted in the monomethyl derivative XVI and the dimethyl derivative XVII which afforded by alkaline hydrolysis the acids XVIII and XIX.Attempts at their cyclization with polyphosphoric acid to the corresponding 11-methylated dibenzothiepin-10(11H)ones are described.
- Jilek, Jiri,Pomykacek, Josef,Holubek, Jiri,Svatek, Emil,Ryska, Miroslav,et al.
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p. 603 - 620
(2007/10/02)
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- One-Electron Chemical Reductions of Phenylalkylsulfonium Salts
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Twenty-two arylalkylsulfonium salts have been reduced with potassium in graphite in tetrahydrofuran and the sulfide products identified.Two trialkylsulfonium salts did not reduce under these conditions.Comparison of the sulfides from a series of monophenylalkylsulfonium salts reveals a leaving-group propensity of benzyl > secondary > primary > methyl > phenyl in a ratio of 28:(6.0 +/- 0.3):1.0:(0.53 +/- 0.09): 0.05.The cleavage ratio is shown to be independent of the electron source and the homogeneity of heterogeneity of the reaction in two cases.Multiplicative transitivity of the above ratios is not observed, although the same qualitative order is found for other comparisons.These results are interpreted in terms of the initial formation of a ?-ligand radical anion sulfonium cation, which undergoes cleavage to a carbon radical and a sulfide.This appears to be the first evidence for this type of structure in a sulfur system.Leaving-group propensities different from the above order are observed in reductions of diphenylsulfonium and benzo-fused sulfonium salts, and rationales are offered.The intermediates in these reactions appear to be different from those involved in radical additions to, or displacements on, sulfur.
- Beak, Peter,Sullivan, Thomas A.
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p. 4450 - 4457
(2007/10/02)
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- Phase-Transfer-Catalyzed Oxidation and Reduction of Organosulfur Compounds with Dichlorocarbene. Mechanism and Synthetic Utility
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Diaryl and dialkyl sulfoxides undergo facile phase-transfer-catalyzed (PTC) deoxygenation with dichlorocarbene at 25 deg C to afford excellent yields of sulfides.Comparisons of deoxygenation rates of dialkyl and diaryl sulfoxides suggest that steric acceleration occurs with the bulky sulfoxides while resonance interactions from aromatic rings retard the reduction.Less bulky sulfides also undergo the reverse reaction: addition of dichlorocarbene to the sulfide with hydrolysis of the dialkyl dichloromethylide with hydroxide ion to afford the corresponding sulfoxide. "Oxidation" of trans-thiadecalin by reaction with PTC dichlorocarbene addition followed by basic hydrolysis is highly stereoselective, affording 94 percent axial and 6 percent equatorial sulfoxide.
- Dyer, John C.,Evans, Slayton A.
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p. 5350 - 5355
(2007/10/02)
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- Organosulfur Compounds, L. - 2H-Thiopyrans and Dihydro-2H-thiopyrans, Synthons for Thiophenes
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2H-Thiopyran derivatives yield thiophenes on pyrolysis at 240-260 deg C.The influence of substitution in positions 3 to 6 of the 2H-thiopyrans on these new thermal rearrangement and fragmentation reactions is dealt with, and some proposed mechanisms are discussed in detail.A novel three-step synthesis of thiophenes from carbonyl compounds via the corresponding thiones, their -cycloaddition with 1,3-dienes with formation of dihydro-2H-thiopyrans and subsequent thermal conversion is described.In this reaction sequence, whose scope and limitations are outlined, t he thiocarbonyl compound contributes the sulfur and the 1,3-diene the carbon skeleton of the desired thiophenes.
- Praefcke, Klaus,Weichsel, Christian
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p. 1604 - 1619
(2007/10/02)
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