- Shuttle arylation by Rh(I) catalyzed reversible carbon–carbon bond activation of unstrained alcohols
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The advent of transfer hydrogenation and borrowing hydrogen reactions paved the way to manipulate simple alcohols in previously unthinkable manners and circumvented the need for hydrogen gas. Analogously, transfer hydrocarbylation could greatly increase the versatility of tertiary alcohols. However, this reaction remains unexplored because of the challenges associated with the catalytic cleavage of unactivated C–C bonds. Herein, we report a rhodium(I)-catalyzed shuttle arylation cleaving the C(sp2)–C(sp3) bond in unstrained triaryl alcohols via a redox-neutral β-carbon elimination mechanism. A selective transfer hydrocarbylation of substituted (hetero)aryl groups from tertiary alcohols to ketones was realized, employing benign alcohols as latent C-nucleophiles. All preliminary mechanistic experiments support a reversible β-carbon elimination/migratory insertion mechanism. In a broader context, this novel reactivity offers a new platform for the manipulation of tertiary alcohols in catalysis.
- Lutz, Marius D.R.,Gasser, Valentina C.M.,Morandi, Bill
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supporting information
p. 1108 - 1119
(2021/04/19)
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- Dual Nickel- And Photoredox-Catalyzed Reductive Cross-Coupling of Aryl Halides with Dichloromethane via a Radical Process
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The first catalytic strategy to harness a new chloromethane radical from dichloromethane under dual Ni/photoredox catalytic conditions has been developed. Compared with traditional two-electron reductive process associated with metallic reductants, this method via a single-electron approach can proceed under exceptionally mild conditions (visible light, ambient temperature, no strong base) and exhibits complementary reactivity patterns. It affords a broad scope of many functional groups, including alkenyl, which suffers cyclopropanation in previous routes. The diarylmethane-d2 compounds can be readily available with this transformation.
- Xu, Tao,Xu, Wenhao,Zheng, Purui
-
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- A palladium-catalyzed C-H functionalization route to ketones: Via the oxidative coupling of arenes with carbon monoxide
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We describe the development of a new palladium-catalyzed method to generate ketones via the oxidative coupling of two arenes and CO. This transformation is catalyzed by simple palladium salts, and is postulated to proceed via the conversion of arenes into high energy aroyl triflate electrophiles. Exploiting the latter can also allow the synthesis of unsymmetrical ketones from two different arenes.
- Arndtsen, Bruce A.,Kinney, R. Garrison,Levesque, Taleah M.
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p. 3104 - 3109
(2020/03/27)
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- Method for preparing symmetric diarylketone through catalytic oxidative carbonylation
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The invention discloses a method for preparing symmetric diarylketone of a formula (I) as shown in the description. The method comprises the following steps: mixing arylboronic acid (II) (Ar-B(OH)2 (II)), a palladium catalyst, a promoter and an organic solvent in a reactor, introducing air and CO having a volume ratio of (7-19):1, reacting under the conditions of a pressure of 1-6 atm and a temperature of 30-80 DEG C for 8-16 hours, and performing after-treatment on the reaction solution, thereby obtaining the product symmetric diarylketone. According to the method disclosed by the invention,the air directly serves as an oxidizing agent to replace the O2 to be applied to oxidative carbonylation of the arylboronic acid, and the ratio of the air to CO is beyond an explosion limit. Therefore, the catalytic system is safe and economic. The palladium catalyst is small in dosage and simple in separation and can be recycled for several times. The method disclosed by the invention is mild inreaction condition, excellent in substrate suitability and high in yield.
- -
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Paragraph 0023; 0024; 0025; 0026; 0028
(2019/03/08)
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- Cercosporin-bioinspired selective photooxidation reactions under mild conditions
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The development of an efficient system for selective oxidation of organic compounds to generate more valuable compounds with molecular oxygen is a significant challenge in industrial chemistry. Bioinspired by the ability of naturally occurring perylenequinonoid pigments (PQPs) to generate reactive oxygen species (ROS) upon photoirradiation, here we report that cercosporin, one of the perylenequinonoid pigments, can function as a cost-effective and environmentally friendly photocatalyst for a wide range of selective oxidations, including benzylic C-H bonds to carbonyls, amines to aldehydes, and sulfides to sulfoxides. All of the representative reactions proceeded smoothly with high efficiency under mild conditions. Owing to the use of inexpensive metal-free visible light-driven photocatalyst produced from microbial fermentation with cheap glucose as the starting material and the ease of handling, we expect that this developed method will be particularly attractive for many more applications in synthetic transformation.
- Li, Jia,Bao, Wenhao,Tang, Zhaocheng,Guo, Baodang,Zhang, Shiwei,Liu, Haili,Huang, Shuping,Zhang, Yan,Rao, Yijian
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supporting information
p. 6073 - 6081
(2019/11/20)
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- Nickel-Catalyzed Molybdenum-Promoted Carbonylative Synthesis of Benzophenones
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A nickel-catalyzed molybdenum-promoted carbonylative coupling reaction for the synthesis of benzophenones from aryl iodides has been developed. Various substituted diaryl ketones were synthesized in moderate to excellent yields under CO-gas-free conditions. A synergetic effect of both nickel and molybdenum has been observed, which is also responsible for the success of this transformation.
- Peng, Jin-Bao,Wu, Fu-Peng,Li, Da,Qi, Xinxin,Ying, Jun,Wu, Xiao-Feng
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p. 6788 - 6792
(2018/06/04)
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- Palladium-Catalyzed Carbonylative Homocoupling of Aryl Iodides for the Synthesis of Symmetrical Diaryl Ketones with Formic Acid
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A convenient method for the palladium-catalyzed carbonylative homocoupling of aryl iodides was developed. With formic acid as the CO source, various symmetrical diaryl ketones were synthesized in moderate to good yield in the presence of a palladium catalyst.
- Wu, Fu-Peng,Peng, Jin-Bao,Qi, Xinxin,Wu, Xiao-Feng
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p. 173 - 177
(2017/11/27)
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- Electron Transfer Reactions: KO tBu (but not NaO tBu) Photoreduces Benzophenone under Activation by Visible Light
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Long-standing controversial reports of electron transfer from KOtBu to benzophenone have been investigated and resolved. The mismatch in the oxidation potential of KOtBu (+0.10 V vs SCE in DMF) and the first reduction potential of benzophenone (of many values cited in the literature, the least negative value is -1.31 V vs SCE in DMF), preclude direct electron transfer. Experimental and computational results now establish that a complex is formed between the two reagents, with the potassium ion providing the linkage, which markedly shifts the absorption spectrum to provide a tail in the visible light region. Photoactivation at room temperature by irradiation at defined wavelength (365 or 400 nm), or even by winter daylight, leads to the development of the blue color of the potassium salt of benzophenone ketyl, whereas no reaction is observed when the reaction mixture is maintained in darkness. So, no electron transfer occurs in the ground state. However, when photoexcited, electron transfer occurs within a complex formed from benzophenone and KOtBu. TDDFT studies match experimental findings and also define the electronic transition within the complex as n → π, originating on the butoxide oxygen. Computation and experiment also align in showing that this reaction is selective for KOtBu; no such effect occurs with NaOtBu, providing the first case where such alkali metal ion selectivity is rationalized in detail. Chemical evidence is provided for the photoactivated electron transfer from KOtBu to benzophenone: tert-butoxyl radicals are formed and undergo fragmentation to form (acetone and) methyl radicals, some of which are trapped by benzophenone. Likewise, when KOC(Et)3 is used in place of KOtBu, then ethylation of benzophenone is seen. Further evidence of electron transfer was seen when the reaction was conducted in benzene, in the presence of p-iodotoluene; this triggered BHAS coupling to form 4-methylbiphenyl in 74% yield.
- Nocera, Giuseppe,Young, Allan,Palumbo, Fabrizio,Emery, Katie J.,Coulthard, Graeme,McGuire, Thomas,Tuttle, Tell,Murphy, John A.
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supporting information
p. 9751 - 9757
(2018/07/21)
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- Acenequinocumulenes: Lateral and Vertical π-Extended Analogues of Tetracyanoquinodimethane (TCNQ)
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We have designed a series of molecules and developed synthetic methodology that allows for the inclusion of structural diversity along both the lateral and vertical axes of the basic TCNQ skeleton. In the lateral direction, benzoannulation extends the π-s
- Gruber, Marco,Padberg, Kevin,Min, Jie,Waterloo, Andreas R.,Hampel, Frank,Maid, Harald,Ameri, Tayebeh,Brabec, Christoph J.,Tykwinski, Rik R.
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supporting information
p. 17829 - 17835
(2017/11/27)
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- Synthesis of Symmetrical Diaryl Ketones by Cobalt-Catalyzed Reaction of Arylzinc Reagents with Ethyl Chloroformate
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Symmetrical diaryl ketones were prepared by a cross-coupling reaction between aryl bromides and ethyl chloroformate. This new method, which uses a catalyst composed of CoBr2and a bipyridine ligand along with readily available starting materials, allows for the synthesis of a variety of symmetrical diaryl ketones in moderate to excellent yields (37–99 %) under mild conditions. This reaction, in which ethyl chloroformate acts as a surrogate of carbon monoxide in the presence of cobalt and zinc, represents an interesting alternative to previously known approaches for the synthesis of diarylmethanones.
- Rérat, Alice,Michon, Christophe,Agbossou-Niedercorn, Francine,Gosmini, Corinne
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p. 4554 - 4560
(2016/09/23)
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- Ligand-Free Palladium-Catalyzed Oxidative Carbonylative Homocoupling of Arylboron Reagents at Ambient Pressure
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Arylboronic acids or potassium aryltrifluoroborates were readily oxidatively carbonylated to their corresponding diaryl ketones in high yields with high selectivities by ligand-free palladium-catalyzed homocoupling at atmospheric pressure. This novel method employs molecular oxygen or iodine as the oxidant and offers an attractive alternative to transition-metal-based oxidant systems.
- Zhao, Hongyuan,Han, Wei
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supporting information
p. 4279 - 4283
(2016/09/14)
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- Visible light-mediated arylalkylation of allylic alcohols through concomitant 1,2-aryl migration
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A photocatalytic process for selective arylalkylation of allylic alcohols with α-bromo diethyl malonate has been developed. The reaction provided a straightforward approach to synthesize α-aryl-β-alkylated ketones via unique 1,2-aryl migration. The procedure is highlighted by its operational simplicity and mild reaction conditions.
- Huang, Hong-Li,Yan, Hang,Yang, Chao,Xia, Wujiong
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p. 4910 - 4913
(2015/03/18)
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- UV light-mediated difunctionalization of alkenes through aroyl radical addition/1,4-/1,2-Aryl shift cascade reactions
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UV light-mediated difunctionalization of alkenes through an aroyl radical addition/1,4-/1,2-aryl shift has been described. The resulted aroyl radical from a photocleavage reaction added to acrylamide compounds followed by cyclization led to the formation of oxindoles, whereas the addition to cinnamic amides aroused a unique 1,4-aryl shift reaction. Furthermore, the difunctionalization of alkenes of prop-2-en-1-ols was also achieved through aroyl radical addition and a sequential 1,2-aryl shift cascade reaction.
- Zheng, Lewei,Huang, Hongli,Yang, Chao,Xia, Wujiong
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p. 1034 - 1037
(2015/03/30)
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- One-pot synthesis of diarylmethanones through palladium-catalyzed sequential coupling and aerobic oxidation of aryl bromides with acetophenone as a latent carbonyl donor
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A one-pot palladium-catalyzed synthesis of symmetrical and unsymmetrical diarylmethanones using acetophenone and aryl bromides as raw materials has been developed. In this reaction, acetophenone acts as a latent carbonyl donor and two pathways of palladium-catalyzed sequential coupling and aerobic oxidation are identified. The reaction is applicable to a spectrum of substrates and delivers the products in moderate to good yields. This method can be used for the synthesis of ketoprofen, a nonsteroidal anti-inflammatory drug, in a two-step procedure and 45% overall yield.
- Wang, Xing,Liu, Fu-Di,Tu, Hai-Yang,Zhang, Ai-Dong
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p. 6554 - 6562
(2014/08/05)
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- Pd/Cu-cocatalyzed aerobic oxidative carbonylative homocoupling of arylboronic acids and CO: A highly selective approach to diaryl ketones
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A highly selective Pd/Cu-cocatalyzed aerobic oxidative carbonylative homocoupling of arylboronic acids has been developed. This method employs a simple catalytic system, readily available boronic acids as the substrates, molecular oxygen as the oxidant, and 1 atm of CO/O2, which makes this method practical for further applications.
- Ren, Long,Jiao, Ning
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supporting information
p. 2411 - 2414
(2014/10/15)
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- Palladium-catalyzed oxidative carbonylation for the synthesis of symmetrical diaryl ketones at atmospheric co pressure
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A mild and efficient synthesis of symmetrical diaryl ketones by palladium-catalyzed oxidative carbonylation of arylboronic acids with carbon monoxide at atmospheric pressure is reported. Georg Thieme Verlag Stuttgart New York.
- Li, Yang,Lu, Wei,Xue, Dong,Wang, Chao,Liu, Zhao-Tie,Xiao, Jianliang
-
supporting information
p. 1097 - 1100
(2014/05/20)
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- Indole synthesis: palladium-catalyzed C-H bond amination via reduction of nitroalkenes with carbon monoxide
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Nitroalkenes have been called 'chemical chameleons' due to their versatility in numerous synthetic transformations. Herein, we describe the first transition metal-catalyzed transformation of conjugated nitroalkenes into indoles. Under mild reaction condit
- Hsieh, Tom H.H.,Dong, Vy M.
-
supporting information; experimental part
p. 3062 - 3068
(2009/09/05)
-
- Synthesis and electroluminescent properties of fully substituted ethylene moieties
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We synthesized a new bluish-green emitting material using fully substituted ethylene moieties, 1,1,2,2-tetrakis(4-tert-butyl-phenyl)ethene [TBPE] and 1,1,2,2-tetrakis(4-tert-butyl-biphenyl)ethene [TBBPE] by McMurry reaction. These products were identified
- Kim, Soo Kang,Park, Young Il,Park, Jong Wook
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p. 209 - 216
(2007/10/03)
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- CROSSLINKED METALLOCENE COMPOUND FOR OLEFIN POLYMERIZATION AND METHOD OF POLYMERIZING OLEFIN WITH THE SAME
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The bridged metallocene compound or the olefin polymerization catalyst which comprises the compound, enables high polymerization activity in polymerizing one or more monomers selected from ethylene and α-olefins. The bridged metallocene compound contains
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Page/Page column 40
(2010/02/12)
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- ION CHANNEL MODULATORS
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The invention relates to compounds, compositions comprising the compounds, and methods of using the compounds and compound compositions. The compounds, compositions, and methods described herein can be used for the therapeutic modulation of ion channel fu
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Page/Page column 86
(2010/02/14)
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- Photochemistry and photophysics of (p-benzoylphenyl)diphenylmethyl and (p-benzoylphenyl)bis(4-tert-butylphenyl)methyl radicals in different solvents
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The photochemical reactions of (p-benzoylphenyl)diphenylmethyl (1) and (p-benzoylphenyl)bis(4-tert-butylphenyl)methyl (2) in various solvents were investigated. The photophysical parameters of the first excited doublet state of the radicals were measured using spectroscopic and kinetic methods and led to a 'molecular rotor' model to characterize the excited-state behavior. The charge-transfer excited state for both radicals was observed. Photoproducts separated from the photolysis of 1 and 2 in benzene suggest photodecomposition proceeds via H-abstraction (55%), fragmentation (20%), cyclization (10%), and addition (10%).
- Jarikov, Viktor V.,Nikolaitchik, Alexandre V.,Neckers, Douglas C.
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p. 5131 - 5140
(2007/10/03)
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- Homolytic base-promoted aromatic alkylations by alkylmercury halides
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Electron transfer chain reactions leading to substitution in electronegatively substituted benzene derivatives can be observed with alkylmercury halides in the presence of proton accepters such as DABCO. Promotion by base involves the abstraction of a proton from the substituted cyclohexadienyl adduct radical to form a radical anion which readily transfers an electron to RHgX with the regeneration of R.. Aromatic substitutions involving t-Bu. are highly regioselective and yield products of only para attack for PhCHO, PhCOCH3, PhCOCMe3, PhCOPh, PhCN, phthalimides, or 1,2-dicyanobenzene. The ortho/para substitution products are observed for isophthaldehyde or 1,3-dicyanobenzene, while 1,4-dicyanobenzene yields the ortho substitution product. At 25-35°C substitution by t-Bu. ortho to an ester group is not observed and m- or p-cyanobenzoate esters yield only products of substitution ortho to the cyano group. With the isopropyl radical substitution ortho to the ester function is observed with diethyl isophthalate. Intramolecular radical cyclizations of the radical adducts of 1-aryl-4-penten-1-ones leading to α-tetralones is also promoted by the presence of DABCO. When the aryl group contains a para ester function, spirocyclizatien occurs leading to a rearrangement acyl radical which can be oxidized by t-BuHgCl to the acyl cation and the carboxylic acid.
- Russell, Glen A.,Chen, Ping,Kim, Byeong Hyo,Rajaratnam, Ragine
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p. 8795 - 8801
(2007/10/03)
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- New Triarylmethyl Derivatives: "Blocking Groups" for Rotaxanes and Polyrotaxanes
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Five triarylcarbinols (8, three new compounds) were synthesized.Using carbanion chemistry the triarylmethanes (13, five new compounds) made by formic acid reduction of 8 were converted to the ω,ω,ω-triarylalkanols (15, three new compounds) and thence to the chloro (17) and iodo (18) derivatives (five new compounds).Via carbocation chemistry p-(triarylmethyl)phenols (20, two new compounds) and aniline (21, new compound) were produced.Alkylation of 20 yielded alcohol (22), benzylic bromide (23), and carboxy (25) functionalized derivatives.The alcohol, halide, phenol, aniline, and carboxylic acid functionalized triarylmethane compounds are suitable end blocking groups for rotaxanes and polyrotaxanes.
- Gibson, Harry W.,Lee, Sang-Hun,Engen, Paul T.,Lecavalier, Pierre,Sze, Jean,et al.
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p. 3748 - 3756
(2007/10/02)
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- Ring tert-butylation of benzophenones and benzaldehyde with tert-butyllithium and thionyl chloride
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One-flask ring tert-butylation of benzophenones and benzaldehyde with tert-butyllithium and thionyl chloride is reported. The scope of the reaction and the suggested mechanism are discussed.
- Olah,Wu,Farooq
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p. 1179 - 1182
(2007/10/02)
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- Reactions of some p-Substituted Triphenylmethyl Chlorides with Alcohols, Alkali-metal Alcoholates, and Tributylamine
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The p-methoxylated triphenylmethyl chlorides (4a-c), when heated with alcohols, give mixtures of the corresponding triarylmethanes (5a-c) (via the hydride transfer to the corresponding triarylmethylium cations) and the alkyl (substituted triphenylmethyl) ethers (7a-c) (via polar susbtitution reactions).Part or all of the ether (7c) may be further converted into the substituted triphenylmethanol (6c).In the reaction of the mono-p-methoxylated halides (4a) and (4c) with methanol, the substitution products (7a) and (7c) are formed as the main products, while the main product of the reaction of the di-p-methoxylated halide (4b) with methanol is the substituted triphenylmethane (5b).When the methanol is replaced by 2H4> methanol, no reduction product is formed from the halide (4c).Reaction of halide (4c) with ethanol furnishes exclusively the substituted triphenylmethane (5c).The p-chlorophenyl(diphenyl)methyl chloride (4d) gives, with methanol, mainly or exclusively the ether (7d), and with ethanol, under mild conditions, gives the ether (9d).However, under vigorous conditions, the substituted triphenylmethane (5d) is formed.The reduction of the p-methoxylated triphenylmethyl chloride (4c) by alcohols as well as its conversion into alkyl (p-methoxylated triphenylmethyl) ethers are accompanied, to a certain degree, by exchange of the p-methoxy group of the substrate and the alkoxy group of the alcohol; no similar exchange of the p-chlorine atom of halide (4d) was observed.Explanations for all obsrved diferences are offered.The reactions of the substituted triphenylmethyl chlorides (4b-d) with alkoxides in the corresponding alcohols give the corresponding alkyl (substituted triphenylmethyl) ethers (7b), (7c), (9c), and (9d), respectively, in excellent yields.The reaction of the triarylmethyl chloride (4d) with potassiumt-butoxide in THF in the presence of acetone led, among other products, to the formation of oligomeric material which indicates the operation of single-electron-transfer induced processes.Reaction of the same chloride (4d) with tributylamine in refluxing cumene or t-butylbenzene led to the exclusive formation of a series of products all of which may be derived from the intermediacy of the substituted triphenylmethyl radical (18); the latter, in turn, is thought to arise as a result of dissociative electron transfer from tributylamine to chloride (4d).
- Izso, Gyoengyi,Huszthy, Peter,Lempert, Karoly,Fetter, Jozsef,Simig, Gyula,et al.
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p. 769 - 778
(2007/10/02)
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- Extent of Charge Transfer in the Photoreduction of Phenyl Ketones by Alkylbenzenes
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Rate constants for triplet-state reaction of various ring-substituted benzophenones (BPs), acetophenones (APs), and α,α,α-trifluoroacetophenones (TFAs) with toluene and p-xylene have been determined by a combination of flash kinetics, steady-state quenching, and quantum yield measurements.The relative amounts of primary and tertiary radicals formed by reaction of the same ketons with p-cymene have also been measured.For all three types of ketones, rate constants correlate well with triplet ketone reduction potentials.The magnitude of the kinetic isotope effects observed with toluene-d8 and p-xylene-d10 diminishes as the ketones become easier to reduce.All of the ketone triplets react with alkylbenzenes primarily by a charge-transfer mechanism, with the rate-determining step changing from complexation to hydrogen transfer as the ketones become harder to reduce.The least reactive AP triplets probably react significantly via simple hydrogen atom abstraction as well.Those ketones with n,?* lowest triplets (all BPs and some APs) react with p-cymene to give primary/tertiary radical ratios that vary no more than a factor of 2 from the 0.40 value displayed by tert-butoxy radicals; those with ?,?* lowest triplets (TFAs and some APs) give ratios that favor primary radicals and that vary by an order of magnitude with the triplet ketone reduction potential.The variation in cymene product ratios reflect different orientations for attack on cymene by n,?* and ?,?* triplets and differing degrees of partial electron transfer within the exciplexes, which are not tight radical ion pairs.The variation seen for ?,?* triplets represents a stereoelectronic effect within face-to-face exciples, as evidenced by the excerptional behavior of p-diacylbenzenes, which give the highest ratio of tertiary radicals from cymene.There is no set intrinsic ratio of reactivity for ?,?* triplets vs. n,?* triplets in these CT reactions.The two types of triplets show similar reactivity for the more easily reduced triplets, with the harder to reduce ?,?* triplets being only one-tenth as reactive as n,?* triplets of comparable triplet reduction potential.When the extent of electron transfer in the exciplex is small, hydogen transfer is rate determining and ?,?* reactivity drops.A study of two radical reactions which generate benzyl and α-hydroxy-α-methylbenzyl radicals indicates that radical disproportionation cannot explain the low quantum yields (0.10) of most ketone-toluene photoreductions, which apparently involve substantial radiation less decay by the exciplex intermediates.
- Wagner, Peter J.,Truman, Royal J.,Puchalski, Alan E.,Wake, Ronald
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p. 7727 - 7738
(2007/10/02)
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- CATALYTIC CARBONYLATION OF DIARYLIODONIUM SALTS PROMOTED BY PALLADIUM-ZINC SYSTEM. A NEW SYNTHESIS OF DIARYL KETONES AND DIARYL-α-DIKETONES
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Diaryliodonium salts react with carbon monoxide, in the presence of zinc and a catalytic amount of palladium acetate, to give a mixture of the corresponding diaryl ketones and diaryl-α-diketones under mild conditions.
- Uchiyama, Masaharu,Suzuki, Takehiko,Yamazaki, Yasuo
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p. 1201 - 1202
(2007/10/02)
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- Stable Carbenium Ions, 29. - Diarylhydroxycarbenium Perchlorates
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Diarylhydroxycarbenium perchlorates are prepared as crystalline salts and are characterised.
- Volz, Heinrich,Mayer, Wilhelm Dietrich
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p. 1424 - 1428
(2007/10/02)
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