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Carbenium Ions in Substitution Reactions at the Amino Nitrogen Atom
Tropylium, xanthylium, and tritylium salts characterized by different stabilities differently reacted with biologically active amines. The reactions of tropylium perchlorate and tetrafluoroborate with 4-(cyclohepta-2,4,6-trien-1-yl)aniline was accompanied
Yunnikova,Esenbaeva
(2018)
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A C-to-O atom-swapping reaction sequence enabled by Ni-catalyzed decarbonylation of lactones
Advances in site-selective functionalization reactions have enabled single atom changes on the periphery of a complex molecule, but reaction manifolds that enable such changes on the core framework of the molecule remain sparse. Here, we disclose a strategy for carbon-to-oxygen substitution in cyclic diarylmethanes and diarylketones to yield cyclic diarylethers. Oxygen atom insertion is accomplished by methylene and Baeyer-Villiger oxidations. To remove the carbon atom in this C-to-O atom swap process, we developed a nickel-catalyzed decarbonylation of lactones to yield the corresponding cyclic diaryl ethers. This reaction was enabled by mechanistic studies with stoichiometric nickel(ii) complexes that led to the optimization of a ligand capable of promoting a challenging C(sp2)-O(aryl) reductive elimination. The nickel-catalyzed decarbonylation was applied to 6-8 membered lactones (16 examples, 32-99%). Finally, a C-to-O atom-swapping reaction sequence was accomplished on a natural product and a pharmaceutical precursor.
Li, Junqi,Luu, Quang H.
p. 1095 - 1100
(2022/02/02)

High-Fidelity Dimerization of Xanthenyl Radicals and Dynamic Qualities of a Congested Ethane: Diethyl Dixanthenyl-9,9′-Dicarboxylate
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.
supporting information

(2021/12/23)

Method for reducing carbonyl reduction to methylene under illumination
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; 0135-0139

(2021/09/29)

Formation and Disproportionation of Xanthenols to Xanthenes and Xanthones and Their Use in Synthesis
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
p. 3334 - 3343
(2021/02/05)

Lewis Acid Catalyzed Reductive Cyclization of 2-Aryloxybenzaldehydes and 2-(Arylthio)benzaldehydes to Unsubstituted 9H-Xanthenes and Thioxanthenes in Diisopropyl Ether
Readily accessible 2-aryloxybenzaldehydes and 2-(arylthio)benzaldehydes undergo a sequence of reactions leading to a wide variety of unsubstituted 9H-xanthenes and thioxanthenes in high yields when heated with a Lewis acid in diisopropyl ether. This reductive cyclization method is compatible with several important functional groups. The method is also applicable for the selective reductive cyclization of the more electron-rich aryl ring of a 2,6-bis(aryloxy)benzaldehyde. The key feature of this transformation is the chemoselective reduction of a transient xanthylium ion in the presence of aldehydic group via intermolecular hydride transfer from diisopropyl ether (solvent). (Figure presented.).
Verma, Shashi Kant,Prajapati, Anamika,Saini, Manoj Kumar,Basak, Ashok K.
p. 532 - 539
(2020/11/30)

Electrochemically Mediated Direct C(sp3)?H Sulfonylation of Xanthene Derivatives
The construction of C(sp3)-sulfonyl bonds through direct sulfonylation of C(sp3)?H bond presents a number of challenges, so an electrochemical oxidation-induced direct sulfonylation of the xanthene C(sp3)?H bond was developed. Significant advantages of this method are high atom efficiency, functional group tolerance, transition metal- and oxidant-free conditions. The in vitro cytotoxicity of all product is evaluated by MTT assay against human cancer cell lines. The results reveal that most of the compounds 3 da and 3 af have good inhibitory activity on tumor cell lines. (Figure presented.).
Feng, Yu-Feng,Gao, Lei,Ma, Xian-Li,Mo, Zu-Yu,Pan, Ying-Ming,Tang, Hai-Tao,Wei, Wan-Jie,Zhong, Yu-Jing
supporting information

(2022/01/06)

Access to Cyanoimines Enabled by Dual Photoredox/Copper-Catalyzed Cyanation of O-Acyl Oximes
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
supporting information
p. 7315 - 7320
(2020/10/02)

Iodine-catalyzed efficient synthesis of xanthene/thioxanthene-indole derivatives under mild conditions
An iodine-catalyzed nucleophilic substitution reaction of xanthen-9-ol and thioxanthen-9-ol with indoles has been developed, providing an efficient procedure for the synthesis of xanthene/thioxanthene-indole derivatives with good to excellent yields. This protocol offers several advantages, such as short reaction times, green solvent, operational simplicity, easily available catalyst and mild reaction conditions. Moreover, this method showed good tolerance of functional groups and a wide range of substrates.
Bai, Mengjiao,Duan, Hengpan,Duan, Suyue,Miao, Weihang,Wang, Xuequan,Yang, Zhixin,Ye, Pingting
p. 25165 - 25169
(2020/07/14)

Electrochemical Hydrogenation with Gaseous Ammonia
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
supporting information
p. 1759 - 1763
(2019/01/16)

Copper-Catalyzed One-Pot Synthesis of Dibenzofurans, Xanthenes, and Xanthones from Cyclic Diphenyl Iodoniums
Oxygenation of cyclic diphenyl iodoniums (CDPIs) with varied medium-ring sizes has been fully investigated. This practical copper-catalyzed tandem reaction of CDPIs with water as the oxygen source enables the construction of derivatised dibenzofurans and xanthenes at moderate to good yields. Moreover, structurally important xanthones are also successfully accessed under the oxygenation conditions with additional TEMPO.
Zhu, Daqian,Li, Min,Wu, Zhouming,Du, Yongliang,Luo, Bingling,Huang, Peng,Wen, Shijun
p. 4566 - 4571
(2019/07/09)

An Efficient Ga(OTf)3/Isopropanol Catalytic System for Direct Reduction of Benzylic Alcohols
This study aims to report the first gallium-catalyzed direct reduction of benzylic alcohols using isopropanol as a reductant. The reaction proceeds via gallium catalyst-assisted hydride transfer of the in situ-generated benzylic isopropyl ether. The method generates only water and acetone as byproducts and thus provides an atom-economic and environmentally friendly approach to the synthesis of di- and triarylmethanes, which are important substructures in various bioactive compounds and functional materials. (Figure presented.).
Sai, Masahiro
supporting information
p. 4330 - 4335
(2018/10/15)

Iodine-catalyzed transformation of aryl-substituted alcohols under solvent-free and highly concentrated reaction conditions
Iodine-catalyzed transformations of alcohols under solvent-free reaction conditions (SFRC) and under highly concentrated reaction conditions (HCRC) in the presence of various solvents were studied in order to gain insight into the behavior of the reaction intermediates under these conditions. Dimerization, dehydration and substitution were the three types of transformations observed with benzylic alcohols. Dimerization and substitution reactions were predominant in the case of primary- and secondary alcohols, whereas dehydration prevailed in the case of tertiary alcohols. The relative reactivity of substituted 1-phenylethanols in I2-catalyzed dimerization under SFRC provided a good Hammett plot ρ+ = -2.8 (r2 = 0.98), suggesting the presence of electron-deficient intermediates with a certain degree of developed charge in the rate-determining step.
Jereb, Marjan,Vra?i?, Dejan
p. 747 - 762
(2018/01/17)

PRODUCTION PROCESS FOR XANTHENE
PROBLEM TO BE SOLVED: To provide a process for producing xanthene which is industrially very useful as a pharmaceutical intermediate, with high yield and high selectivity, by a very convenient process of reacting sodium dihydro-bis(2-methoxyethoxy)aluminate and xanthone in an organic solvent. SOLUTION: Provided is a process for producing xanthene with high yield and high selectivity by, for example, reacting sodium dihydro-bis(2-methoxyethoxy)aluminate and xanthone in an organic solvent such as toluene. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0030; 0031

(2017/05/06)

Method of manufacturing dihydroxyxanthene (by machine translation)
PROBLEM TO BE SOLVED: a dihydroxyxanthene industrially useful as an intermediate, in the presence of a tertiary amine compound 3, alkyltrichlorosilane after reduction, or acid dissociation constant (pKa) is 1 or less in the presence of strong, trialkylsilane compd. Xhanthone is reduced, the silane compound without isolating the simple method by hydrolysis, in high selectivity · high yield. SOLUTION: Xhanthone to triethylamineborane, triisopropylamine presence of 3 such as a tertiary amine compound, or a reducing alkyltrichlorosilane, triphloroacetic acid, acid dissociation constant (pKa) methansulfonate below 1 such that the presence of a strong, triethylsilane, diisopropylbenzene trialkylsilane compound such as a silane is reduced, to provide a method of manufacturing a dihydroxyxanthene. Selected drawing: no (by machine translation)
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Paragraph 0053-0055

(2017/07/05)

Gold(I) carbenes by retro-buchner reaction: Generation and fate
The fate of the aryl gold(I) carbenes generated by retro-Buchner reaction of ortho-substituted 7-aryl-1,3,5-cycloheptatrienes is dependent on the constitution of the ortho substituent. Indenes and fluorenes are obtained by intramolecular reaction of highly electrophilic gold(I) carbenes with alkenes and arenes. According to density functional theory calculations, the gold-catalyzed retro-Buchner process occurs stepwise, although the two carbon-carbon cleavages occur on a rather flat potential energy surface.
Wang, Yahui,McGonigal, Paul R.,Herle, Bart,Besora, Maria,Echavarren, Antonio M.
supporting information
p. 801 - 809
(2014/02/14)

Synergistic effect of ketone and hydroperoxide in Bronsted acid catalyzed oxidative coupling reactions
Waste not wasted: A mechanistic study of the autoxidative coupling of xanthene with cyclopentanone uncovered an autoinductive effect of the waste product hydrogen peroxide. It generates radicals in the presence of acid and ketones, which accelerate the reaction by providing an additional pathway to the reactive hydroperoxide intermediate. This discovery could be applied to achieve other Bronsted acid catalyzed oxidative coupling reactions.
Schweitzer-Chaput, Bertrand,Sud, Abhishek,Pinter, Aron,Dehn, Stefanie,Schulze, Philipp,Klussmann, Martin
supporting information
p. 13228 - 13232
(2014/01/06)

A highly efficient thiourea catalyzed dehydrative nucleophilic substitution reaction of 3-substituted oxindoles with xanthydrols
We report a highly efficient thiourea catalyzed dehydrative nucleophilic substitution reaction. The Schreiner's thiourea catalyst A1 catalyzed the alkylation of 3-substituted oxindoles with xanthydrols well, to furnish quaternary oxindoles in high yield. The ESI-MS analysis confirms the interaction of 3-substituted oxindole 1 with the thiourea, which might facilitate the oxindole-hydroxindole tautomerization for the alkylation. The Royal Society of Chemistry 2013.
Chen, Long,Zhu, Feng,Wang, Cui-Hong,Zhou, Jian
p. 19880 - 19884
(2013/11/06)

Visible light-driven aerobic oxidation catalyzed by a diiron(IV) μ-oxo biscorrole complex
Under visible light irradiation, the diiron(IV) μ-oxo-bis(5,10,15- tripentafluorophenylcorrole) complex catalyzes the aerobic oxidations of hydrocarbons in sequences employing photo-disproportionation reactions. The active oxidant, highly reactive corrole-iron(V)-oxo species, can be detected in real time via laser flash photolysis methods.
Zhang, Rui,Vanover, Eric,Chen, Tse-Hong,Thompson, Helen
p. 95 - 100
(2013/07/26)

Synthesis of dihydrodibenzo[b,f]furo[2,3-d]oxepins and related reactions
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
p. 2491 - 2503,13
(2020/08/24)

1,3-Dichloro-tetra-n-butyl-distannoxane: A new application for catalyzing the direct substitution of 9H-xanthen-9-ol at room temperature
1,3-Dichloro-tetra-n-butyl-distannoxane was firstly used to catalyze the direct substitution of 9H-xanthen-9-ol with indoles at room temperature to afford a class of 3-(9H-xanthen-9-yl)-1H-indole derivatives in good to excellent isolating yield. Moreover, other nucleophiles (such as diketone and pyrrole) could also proceed smoothly in this methodology. Copyright
Liu, Ling-Yan,Zhang, Yan,Huang, Kai-Meng,Chang, Wei-Xing,Li, Jing
experimental part
p. 9 - 15
(2012/03/11)

Imbalanced tunneling ready states in alcohol dehydrogenase model reactions: Rehybridization lags behind H-tunneling
The secondary kinetic isotope effects for the hydride transfer reactions from aliphatic alcohols to two carbocations (NAD+ models) in acetonitrile were determined. The results suggest that the hydride transfer takes place by tunneling and that the rehybridizations of both donor and acceptor carbons lag behind the H-tunneling. This is quite contrary to the observations in alcohol dehydrogenases where the importance of enzyme motions in catalysis is manifested.
Hammann, Blake,Razzaghi, Mortezaali,Kashefolgheta, Sadra,Lu, Yun
supporting information
p. 11337 - 11339
(2013/01/15)

XANTHENE BASED SEMICONDUCTOR COMPOSITIONS
A small molecule semiconductor of Formula (I): wherein R1, R2, R3 and R4 are independently selected from a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted ethynyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, an alkoxy group, an alkylthio group, an alkylsilyl group, a cyano group, and a halogen atom, wherein n is 1 or 2, and wherein X is independently S or
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(2012/09/22)

Reaction of benzyne with formamides and acetylimidazole
The reaction of DMF with o-trimethylsilylphenyl triflate in the presence of CsF afforded dimethyldiphenylammonium triflate, xanthene, and xanthone in 62%, 16%, and 24% yields, respectively. On the other hand, the reaction of dimethylthioformamide with triflate and CsF resulted in diphenyl sulfide, xanthene, and xanthone in 62%, 10%, and 12% yields, respectively. The reaction of acetylimidazole with benzyne gave 9-N,N-diphenylaminoanthracene in 85% yield.
Okuma, Kentaro,Nojima, Akiko,Nakamura, Yuki,Matsunaga, Nahoko,Nagahora, Noriyoshi,Shioji, Kosei
experimental part
p. 328 - 332
(2011/05/14)

Lewis acid-catalysed one pot synthesis of substituted xanthenes
A direct synthesis of substituted xanthenes from salicylaldehydes and cyclohexenones or tetralones has been developed. The reaction is catalysed by Lewis acids like scandium triflate and furnishes substituted xanthenes in good to excellent yields using either microwave or thermal heating. Microwave heating results in significantly shortened reaction times of 30 min and generally higher yields.
Boe, Esther,Hillringhaus, Tim,Nitsch, Jacqueline,Klussmann, Martin
supporting information; experimental part
p. 1744 - 1748
(2011/04/24)

Synthesis of dibenz[b,f]oxepins via manganese(III)-based oxidative 1,2-radical rearrangement
(Chemical Equation Presented) The oxidation of monoalkyl 2-(9H-xanthenyl)malonates 1 with Mn(OAc)3 gave the 9- or 10-dibenz[b,f]oxepincarboxylates 2 in good yields. The reaction proceeds with high regioselectivity except for the case of (1-meth
Cong, Zhiqi,Miki, Takumi,Urakawa, Osamu,Nishino, Hiroshi
scheme or table
p. 3978 - 3981
(2009/10/14)

Reaction of benzyne with salicylaldehydes: General synthesis of xanthenes, xanthones, and xanthols
The reaction of salicylaldehydes with benzyne prepared from o-trimethylsilyphenyl triflate and CsF gave xanthenes and xanthones. When the reaction was carried out under basic conditions, 9-hydroxyxanthenes (xanthols) were obtained in good yields.
Okuma, Kentaro,Nojima, Akiko,Matsunaga, Nahoko,Shioji, Kosei
supporting information; experimental part
p. 169 - 171
(2009/06/20)

Mixture of Sulfide Dyes
Disclosed are mixtures of sulfide dyes and dyeing compositions comprising mixtures of sulfide dyes. The dye mixtures are useful for the dyeing of organic materials, such as keratin fibers, preferably human hair.
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(2009/05/29)

COMPOSITIONS AND THEIR USES FOR GENE THERAPY OF BONE CONDITIONS
In certain preferred embodiments, the present invention provides compositions and methods for the treatment of bone conditions associated with low bone density. In preferred embodiments, the present invention provides compositions and methods for the treatment of osteoprotegerin-responsive conditions.
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(2009/09/05)

Xanthene Dyes
Disclosed are compounds of formula (1a), wherein R1 is N+R8R9; R8 and/or R9 independently from each other are hydrogen; C1-C12alkyl; or phenyl-C1-C4-alkyl; or R8 and/or R9 are a bivalent C3-C6alkylene radical which is linked to the carbon atoms C1 or C2 respectively and, together with the linking nitrogen atom form a 6 to 16-membered carbocyclic ring; R2 is NR10R11; or OR10; R10 and R11, independently from each other are hydrogen; C1-C12alkyl; or phenyl-C1-C4alkyl; or R10 and/or R11 are a bivalent C3-C6alkylene radical which is linked to the carbon atoms C3 or C4 respectively and, together with the linking nitrogen or oxygen atom form a 6 to 16-membered carbocyclic ring; or R10 and R11 together with the linking nitrogen atom form a 4 to 8 membered carbocyclic ring; R3, R4, R5, R6 and R7 independently form each other are hydrogen; C1-C12alkyl; halogen; NR12R13; or a radical of formula (1a); R12 and R13 independently from each other are hydrogen; C1-C12alkyl; phenyl-C1-C4alkyl; or a radical of formula (1a2); V is —O—; Or —NR15; R14, R15 R-16 and R17 independently from each other are hydrogen; or C1-C5alkyl; and Hal is a halogen atom; and wherein at least one of R3, R4, R5, R6 and R7 is hydrogen. The compounds are useful for dyeing of keratin-containing fibres with or without reducing agents.
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(2009/10/31)

Palladium-catalyzed benzylic arylation of N-benzylxanthone imine
(Chemical Equation Presented) The direct benzylic arylation of N-benzylxanthone imine with aryl chloride proceeds under palladium catalysis, yielding the corresponding coupling product. The product is readily transformed to benzhydrylamine. Taking into consideration that the imine is readily available from benzylic amine, the overall transformation represents a formal cross-coupling reaction of aryl halide with α-aminobenzyl metal.
Niwa, Takashi,Yorimitsu, Hideki,Oshima, Koichiro
supporting information; experimental part
p. 4689 - 4691
(2009/05/13)

Pesticidal composition
The invention relates to a pesticidal composition comprising (a) a water-insoluble solid pesticidal ingredient, (b) a salt of N-phosphonomethylglycine, (c) a salt of polyoxyalkylene alkyl ether phosphate ester, (d) a salt of polyoxyalkylene polystyrylphenyl ether phosphate ester, (e) a thickener and (f) water, wherein said pesticidal ingredient is suspended in the aqueous continuous phase as solid state. The pesticidal composition has excellent suspension stability.
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(2008/06/13)

Oxidation-reduction reactions of 1,3-dithioles and their ions [7]
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Yunnikova,Makhova
p. 1495 - 1496
(2008/09/21)

Xanthene derivatives and ortho-substituted phenols - Products from dehydrogenation of acyclic 1,5-diketones
Xanthene derivatives and ortho-substituted phenols were obtained during the dehydrogenation of 1,5-diketones and their ketol forms at a Pt/C catalyst at 280-320°C. 2005 Springer Science+Business Media, Inc.
Akimova,Kaminsky,Svistunova
p. 1374 - 1380
(2007/10/03)

Oil-in-oil emulsions comprising a silicone, dispersions and use of said emulsions
The invention relates to emulsions comprising two non-aqueous, immiscible liquids, (L1) and (L2), whereby the liquid (L1), which is either the continuous or dispersed phase of the emulsion, is a silicone. The emulsion is further stabilized by at least one graft or block co-polymer of which one fraction is soluble in the dispersed phase the other in the continuous phase, the fraction soluble in the continuous phase being greater than the fraction soluble in the dispersed phase. The invention further relates to dispersions of said emulsions in an aqueous or organic phase and use of said emulsions and dispersions in the field of cosmetic and/or dermatological formulations
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(2008/06/13)

A Novel Two-Carbon Homologation with N-Vinylacetamides and Ethyl Vinyl Ether as Acetaldehyde Anion Equivalents in the Synthesis of 9H-Xanthene, 9H-Thioxanthene, and 9,10-Dihydro-9-acridine Carboxaldehydes
An efficient synthesis of 9H-xanthene-9-carboxaldehyde (3a), 9H-thioxanthene-9-carboxaldehyde (3b), and 9,10-dihydro-10-methyl-9-acridinecarboxaldehyde (3c) by a novel two-carbon homologation of xanthydrol (1a), thioxanthydrol (1b), and 9,10-dihydro-10-methyl-9-acridinol (1c), respectively, using N-vinylacetamides (2a,b) or ethyl vinyl ether (2c) as acetaldehyde anion equivalents, is described.
Prashad, Mahavir,Lu, Yansong,Repic, Oljan
p. 584 - 586
(2007/10/03)

Pinacol Formation and Reduction of Aromatic Carbonyls with Magnesium-Methanol at Ambient Temperature
A simple and inexpensive procedure for the pinacol formation of aromatic aldehydes and reduction of aromatic ketones to the corresponding alcohols with magnesium in dry methanol at ambient temperature is reported. The pinacol formation and reduction are proposed to be proceeding by SET from magnesium.
Khurana, Jitender M.,Bansal, Geeti,Kukreja, Gagan,Pandey, Ravi R.
p. 1365 - 1371
(2007/10/03)

Novel derivatives and analogues of galanthamin
New compounds of general formula I 1
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(2008/06/13)

An old but simple and efficient method to elucidate the oxidation mechanism of NAD(P)H model 1-aryl-1,4-dihydronicotinamides by cations 2-methyl-5-nitroisoquinolium, tropylium, and xanthylium in aqueous solution
Cations 2-methyl-5-mitroisoquinplinium (IQ+), tropylium (T+), and xanthylium (Xn+) were treated by an NAD(P)H model 1-(p-substituted phenyl)-1.4-dihydronicotinamide series (1) in buffered aqueous solution to give the corresponding reduced products by accepting hydride. Effects of the 4-substituents of 1 on the reaction rates were investigated. Hammett's linear free energy relationship analysis on the three reactions of 1 provides the reaction constants of -0.48, -2.2, and -1.4 with IQ+, T+, and Xn+ as the hydride acceptors, respectively. Comparison of the present reactions with the reaction examples whose mechanisms are well-known, such as the reaction of 1 with a one-electron oxidant Fe(CN)6-3, shows that the active site of 1 in the oxidation with IQ+ is at the 4-position on the dihydropyridine ring but that the active site of 1 in the oxidations with T+ and Xn+ is at the 1-position, which is in agreement with the results from the Bronsted-type linear analysis and the relation studies of the logarithm of the second-order rate constants with the oxidation potentials of the hydride donors. According to the dependence of the reaction mechanism on the active site of 1, a conclusion can be made that the reaction of 1 with IQ+ proceeds by direct one-step hydride transfer mechanism, but the reactions of 1 with T+ and Xn+ would take place via multistep hydride transfer mechanism initiated by one-electron transfer.
Zhu,Liu,Zhao,Cheng
p. 370 - 375
(2007/10/03)

Rapid reduction of carbonyls with nickel boride at ambient utemperature
Carbonyl compounds have been reported to undergo rapid reduction with nickel boride generated in situ from anhyd. nickel chloride and sodium borohydride in THF at ambient temperature to the corresponding alcohols in high yields.
Khurana,Chauhan
p. 3485 - 3489
(2007/10/03)

Evolution of products in the combustion of scrap tires in a horizontal, laboratory scale reactor
A horizontal laboratory reactor was used to study the evolution of byproducts from the combustion of scrap tires at five nominal temperatures (ranging from 650 to 1050 °C) and different oxygen:sample ratios A model was used to calculate the bulk air ratio (λ), and the oxygen consumption was discussed considering this ratio λ. More than 100 volatile and semivolatile compounds were identified and quantified by gas chromatography mass spectrometry, plotting their yields vs the bulk air ratio and temperature. Five different behaviors considering the bulk air ratio and the temperature were identified.
Fullana,Font,Conesa,Blasco
p. 2092 - 2099
(2007/10/03)

Process for making antimicrobial agents in aqueous dispersion form containing 2-(4-thiazolyl)-benzimidazole alone or in combination with 1,2-dibromo-2,4-dicyanobutane
Aqueous dispersions of 2-(4-thiazolyl)-benzimidazole (TBZ), alone or in combination with 1,2-dibromo-2,4-dicyanobutane (DBDCB), and processes for making the same, are disclosed. These processes generally comprise mixing a xanthan gum with water, adding TBZ and mixing until uniform. DBDCB dispersions are prepared by mixing xanthan gum with water, adding DBDCB, maintaining the mixture at a temperature below about 40 DEG C., grinding the mixture and mixing until uniform. The TBZ and DBDCB dispersions are then blended to prepare a dispersion containing both active ingredients. A method for inhibiting microbial growth utilizing these dispersions is also claimed.
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(2008/06/13)

Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion
The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres (100-300 μm) at different combustion temperatures (800- 1200 °C) to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy (GC/MS) was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate phases, and their distribution as a function of emission particle size. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes. The experimental results have been analyzed to elucidate the formation mechanisms of PAHs and particles during polystyrene combustion. The implications of these results are also discussed with respect to the control of PAH emissions from municipal waste-to-energy incineration systems. The partitioning of polycyclic aromatic hydrocarbons (PAHs) between particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments to determine the particle size distribution. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes.
Durlak, Susan K.,Biswas, Pratim,Shi, Jichun,Bernhard, Mary Jo
p. 2301 - 2307
(2007/10/03)

Kinetic, thermodynamic and mechanistic studies on the reduction of carbenium ions by NAD(P)H analogues
Hydride transfer mechanisms of the reductions of xanthylium ion by NAD(P)H analogues (i.e. BNAH, HEH and AcrH2) were investigated. Both the kinetic observations and an analysis of thermodynamic driving forces for each mechanistic step in all the possible mechanisms indicate that the reductions are initiated by a rate-determining electron transfer, followed by a fast hydrogen atom abstraction. The mechanism of the reductions of 9-phenylxanthylium and triphenylmethylium ions by BNAH were also investigated and are similarly discussed.
Cheng, Jin-Pei,Lu, Yun
p. 577 - 584
(2007/10/03)

Decomposition of model compounds of phenol resin waste with supercritical water
Model compounds of phenol resin waste such as prepolymers and substituted diphenylmethanes were decomposed into their monomers by the reaction at from 300 to 430 °C with water in 10 ml tubing bomb reactor. The decomposition reactions were accelerated by the addition of alkali salts such as Na2CO3.
Tagaya, Hideyuki,Suzuki, Yu-Ichi,Kadokawa, Jun-Ichi,Karasu, Masa,Chiba, Koji
p. 47 - 48
(2007/10/03)

A new route for the preparation of xanthene derivatives using Friedel-Crafts intramolecular cyclobenzylation
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Yamato, Takehiko,Komine, Masayasu,Nagano, Yoshiaki
p. 300 - 303
(2007/10/03)

Organic reactions catalyzed by methylrhenium trioxide: Dehydration, amination, and disproportionation of alcohols
Methylrhenium trioxide (MTO) is the first transition metal complex in trace quantity to catalyze the direct formation of ethers from alcohols. The reactions are independent of the solvents used: benzene, toluene, dichloromethane, chloroform, acetone, and in the alcohols themselves. Aromatic alcohols gave better yields than aliphatic. Reactions between two different alcohols could also be used to prepare unsymmetric ethers, the best yields being obtained when one of the alcohols is aromatic. MTO also catalyzes the dehydration of alcohols to form olefins at room temperature, aromatic alcohols proceeding in better yield. When primary (secondary) amines were used as the limiting reagent, direct amination of alcohols catalyzed by MTO gave good yields of the expected secondary (tertiary) amines at room temperature. Disproportionation of alcohols to alkanes and carbonyl compounds was also observed for aromatic alcohols in the presence of MTO. On the basis of the results of this investigation and a comparison with the interaction between MTO and water, a concerted process and a mechanism involving carbocation intermediates have been suggested.
Zhu, Zuolin,Espenson, James H.
p. 324 - 328
(2007/10/03)

An effective synthesis of fused cyclic thiopyrans and pyrans by molybdenum(VI) sulfide catalyzed reduction of the corresponding thiopyranones and pyranones
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
p. 687 - 690
(2007/10/02)

THE SELECTIVE FUNCTIONALIZATION OF SATURATED HYDROCARBONS. PART 28. THE ACTIVATION OF BENZYLIC METHYLENE GROUPS UNDER GOAGGIV AND GOAGGV CONDITIONS
Under GoAggIV and GoAggV conditions, cyclohexadienes were oxidized to give aromatic products instead of ketones and alcohols.At the same time, anthracene was oxidized to give anthraquinone.Under GoAggIV and GoAggV conditions, xanthene, fluorene and diphenylmethane were oxidized to give the corresponding xanthone, fluorenone and benzophenone following two possible pathways: a) alkane to alkyl t-butylperoxide to ketone, and b) alkane to ketone, in which alkyl hydroperoxide, derived from oxygen, may be the reaction intermediate.Xanthyl azide was formed when sodium azide was added to the reaction mixture of xanthene under GoAggIV and GoAggV conditions.The reaction of triphenylmethane under GoAggV conditions gave triphenylmethyl t-butyl peroxide as the major product and hydroperoxide as the minor product.When TEMPO was added, triphenylmethyl hydroperoxide was the only product.
Barton, Derek H. R.,Wang, Tie-Lin
p. 1011 - 1032
(2007/10/02)

Thermolabile Hydrocarbons, 34. - Thermal Stability of 9,9'-Bixanthene and 9,9',10,10'-Tetrahydro-10,10,10',10'-tetramethyl-9,9'-bianthracene. - Stabilisation Energies of Planar Benzhydryl Radicals
The thermal cleavage of the central CC bonds in the title compounds was investigated.The activation parameters were obtained from kinetics and the equilibrium enthalpies and entropies from the temperature dependence of the equilibrium radical concentrations, determined by quantitative ESR. ΔH(excit.) and ΔHDiss are nearly identical but not ΔS(excit.) and ΔSDiss, as expected.The radical stabilisation enthalpies RSE obtained from these data (RSE: 7a = 17.9+/-1.3; 7b = 15.6+/-1.4 kcal/mol) correspond closely to twice the RSE of α-phenylethyl radicals (8.0+/-1.5 kcal/mol) determined previously.The smaller RSE of the benzhydryl radical (12.9+/-0.9 kcal/mol), therefore, must be due to its nonplanarity. - Key Words: C-C Bond cleavage, energetics and kinetics of / Radicals, stability of / ESR
Herberg, Clemens,Beckhaus, Hans-Dieter,Ruechardt, Christoph
p. 2065 - 2072
(2007/10/02)