- Catalytic Racemization of Activated Organic Azides
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The first detailed description of the catalytic racemization of activated benzylic and allylic azides under mild conditions is reported. A kinetic analysis of the observed racemization indicates a first-order dependence on azide, a first-order dependence
- Ott, Amy A.,Topczewski, Joseph J.
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- Three-Component Difunctionalization of Cyclohexenyl Triflates: Direct Access to Versatile Cyclohexenes via Cyclohexynes
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Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.
- Cho, Seoyoung,McLaren, E. J.,Wang, Qiu
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supporting information
p. 26332 - 26336
(2021/11/10)
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- Bromomethyl Silicate: A Robust Methylene Transfer Reagent for Radical-Polar Crossover Cyclopropanation of Alkenes
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A general protocol for visible-light-induced cyclopropanation of alkenes was developed with bromomethyl silicate as a methylene transfer reagent, offering a robust tool for accessing highly valuable cyclopropanes. In addition to α-aryl or methyl-substituted Michael acceptors and styrene derivatives, the unactivated 1,1-dialkyl ethylenes were also shown to be viable substrates. Apart from realizing the cyclopropanation of terminal alkenes, the methyl transfer reaction has been further demonstrated to be amenable to the internal olefins. The photocatalytic cyclopropanation of 1,3-bis(1-arylethenyl)benzenes was also achieved, giving polycyclopropane derivatives in excellent yields. With late-stage cyclopropanation as the key strategy, the synthetic utility of this transformation was also demonstrated by the total synthesis of LG100268.
- Luo, Wenping,Fang, Yewen,Zhang, Li,Xu, Tianhang,Liu, Yongjun,Li, Yan,Jin, Xiaoping,Bao, Jiakan,Wu, Xiaodong,Zhang, Zongyong
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supporting information
p. 1778 - 1781
(2020/03/11)
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- Conversion of Carbonyl Compounds to Olefins via Enolate Intermediate
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A general and efficient protocol to synthesize substituted olefins from carbonyl compounds via nickel catalyzed C—O activation of enolates was developed. Besides ketones, aldehydes were also suitable substrates for the presented catalytic system to produce di- or tri- substituted olefins. It is worth noting that this approach exhibited good tolerance to highly reactive tertiary alcohols, which could not survive in other reported routes for converting carbonyl compounds to olefins. This method also showed good regio- and stereo-selectivity for olefin products. Preliminary mechanistic studies indicated that the reaction was accomplished through nickel catalyzed C—O activation of enolates, thus offering helpful contribution to current enol chemistry.
- Cao, Zhi-Chao,Xu, Pei-Lin,Luo, Qin-Yu,Li, Xiao-Lei,Yu, Da-Gang,Fang, Huayi,Shi, Zhang-Jie
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supporting information
p. 781 - 785
(2019/06/24)
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- Nickel-Catalyzed Direct Synthesis of Aryl Olefins from Ketones and Organoboron Reagents under Neutral Conditions
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Nickel-catalyzed addition of arylboron reagents to ketones results in aryl olefins directly. The neutral condition allows acidic protons of alcohols, phenols, and malonates to be present, and fragile structures are also tolerated.
- Lei, Chuanhu,Yip, Yong Jie,Zhou, Jianrong Steve
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supporting information
p. 6086 - 6089
(2017/05/08)
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- Ruthenium(II)-catalyzed olefination: Via carbonyl reductive cross-coupling
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Natural availability of carbonyl groups offers reductive carbonyl coupling tremendous synthetic potential for efficient olefin synthesis, yet the catalytic carbonyl cross-coupling remains largely elusive. We report herein such a reaction, mediated by hydrazine under ruthenium(ii) catalysis. This method enables facile and selective cross-couplings of two unsymmetrical carbonyl compounds in either an intermolecular or intramolecular fashion. Moreover, this chemistry accommodates a variety of substrates, proceeds under mild reaction conditions with good functional group tolerance, and generates stoichiometric benign byproducts. Importantly, the coexistence of KOtBu and bidentate phosphine dmpe is vital to this transformation.
- Wei, Wei,Dai, Xi-Jie,Wang, Haining,Li, Chenchen,Yang, Xiaobo,Li, Chao-Jun
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p. 8193 - 8197
(2017/11/27)
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- FeCl3-Catalyzed Ring-Closing Carbonyl–Olefin Metathesis
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Exploiting catalytic carbonyl–olefin metathesis is an ongoing challenge in organic synthesis. Reported herein is an FeCl3-catalyzed ring-closing carbonyl–olefin metathesis. The protocol allows access to a range of carbo-/heterocyclic alkenes wi
- Ma, Lina,Li, Wenjuan,Xi, Hui,Bai, Xiaohui,Ma, Enlu,Yan, Xiaoyu,Li, Zhiping
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supporting information
p. 10410 - 10413
(2016/08/24)
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- Solid phase synthesizing method of dihydronaphthalene compound
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A solid phase synthesizing method of a dihydronaphthalene compound I belongs to the field of organic chemistry and comprises: 1, using 1% crosslinked polystyrene resin as a carrier to prepare a polystyrene-loaded selenium base succinimide reagent III; 2, under catalyzing of fluoroform sulfonic acid trimethyl estersil, using the III to induce olefin V to be subjected to intramolecular cyclization to form 3-polystyrene-loaded selenium base-1,2,3,4-tetrahydronaphthalene VI; 3, removing VI by an oxidant through oxidation without further separating, thereby directly obtaining dihydronaphthalene I. Raw materials are easy to obtain, the product yield is good, the purity is high, the operation is simple and convenient, the posttreatment is simple and the method has well industrial application prospect.
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Paragraph 0042
(2016/10/10)
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- Bronsted acid catalyzed intramolecular hydroarylation for the synthesis of cycloalkenyl selenides and tellurides
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Trifluoromethanesulfonic acid catalyzed intramolecular hydroarylation of alkynyl selenides and tellurides is developed for the preparation of cycloalkenyl selenide and telluride derivatives through a selective 6- and 7-endo mode. The cycloalkenyl selenides and tellurides can be easily converted into a wide range of other valuable functionalities, including cyclic olefins, allylic alcohols, enynes, 1,3-dienes, and α,β-unsaturated aldehydes. Trifluoromethanesulfonic acid catalyzed intramolecular hydroarylation of alkynyl selenides and tellurides is developed for the preparation of cycloalkenyl selenide and telluride derivatives through a selective 6- and 7-endo mode. The cycloalkenyl selenides and tellurides can be easily converted into a variety of valuable functionalities, including cyclic olefins, allylic alcohols, enynes, 1,3-dienes, and α,β-unsaturated aldehydes. Copyright
- Eom, Dahan,Park, Sangjune,Park, Youngchul,Lee, Kooyeon,Hong, Gilbert,Lee, Phil Ho
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p. 2672 - 2682
(2013/06/04)
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- Ruthenium-catalyzed hydroarylation of methylenecyclopropanes through C-H bond cleavage: Scope and mechanism
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Intermolecular hydroarylation reactions of highly strained methylenecyclopropanes 2-phenylmethylenecyclopropane (1), 2,2- diphenylmethylenecyclopropane (2), methylenespiropentane (3), bicyclopropylidene (4), (dicyclopropylmethylene)cyclopropane (5), and benzhydrylidenecyclopropane (6) through C-H bond functionalization of 2-phenylpyridine (7 a) and other arenes with directing groups were studied. The reaction was very sensitive to the substitution on the methylenecyclopropanes. Although these transformations involved (cyclopropylcarbinyl)-metal intermediates, substrates 1 and 4 furnished anti-Markovnikov hydroarylation products with complete conservation of all cyclopropane rings in 11-93 % yield, whereas starting materials 3 and 5 were inert toward hydroarylation. Methylenecyclopropane 6 formed the products of formal hydroarylation reactions of the longest distal C-C bond in the methylenecyclopropane moiety in high yield, and hydrocarbon 2 afforded mixtures of hydroarylated products in low yields with a predominance of compounds that retained the cyclopropane unit. As byproducts, Diels-Alder cycloadducts and self-reorganization products were obtained in several cases from substrates 1-3 and 5. The structures of the most important new products have been unambiguously determined by X-ray diffraction analyses. On the basis of the results of hydroarylation experiments with isotopically labeled 7 a-[D5], a plausible mechanistic rationale and a catalytic cycle for these unusual ruthenium-catalyzed hydroarylation reactions have been proposed. Arene-tethered ruthenium-phosphane complex 53, either isolated from the reaction mixture or independently prepared, did not show any catalytic activity. Copyright
- Ackermann, Lutz,Kozhushkov, Sergei I.,Yufit, Dmitry S.
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supporting information
p. 12068 - 12077
(2012/10/29)
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- Synthesis of uniformly 13C-labeled polycyclic aromatic hydrocarbons
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Convergent synthetic pathways were devised for efficient synthesis of a series of uniformly 13C labeled polycyclic aromatic hydrocarbons de novo from U-13C-benzene and other simple commercially-available 13C-starting compounds. All target products were obtained in excellent yields, including the alternant PAH U-13C-naphthalene, U-13C-phenanthrene, U-13C-anthracene, U- 13C-benz[a]anthracene, U-13C-pyrene and the nonalternant PAH U-13C-fluoranthene.
- Zhang, Zhenfa,Sangaiah, Ramiah,Gold, Avram,Ball, Louise M.
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p. 5431 - 5435
(2011/09/14)
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- Efficient Br?nsted acid catalyzed hydrations and hydroaminations of (dicyclopropylmethylene)cyclopropane
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(Dicyclopropylmethylene)cyclopropane underwent efficient Br?nsted acid catalyzed hydrations and hydroaminations with H2O and basic amines, respectively, occurring with conservation of all three cyclopropane rings. Georg Thieme Verlag Stuttgart
- Ackermann, Lutz,Kozhushkov, Sergei I.,Yufit, Dmitry S.,Marek, Ilan
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body text
p. 1515 - 1518
(2011/08/03)
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- CROSS-COUPLING OF PHENOLIC DERIVATIVES
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Embodiments of the invention provide methods and materials for chemical cross-coupling reactions that utilize unconventional phenol derivatives as cross-coupling partners. Embodiments of the invention can be used to synthesize a variety of useful organic compounds, for example the anti-inflammatory drug flurbiprofen.
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Page/Page column 8; sheet 3/14; title page
(2011/04/19)
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- Construction of polysubstituted olefins through Ni-Catalyzed direct activation of Alkenyl C-O of substituted alkenyl acetates
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(Figure Presented) Reliable companion: For the first time cross-coupling between alkenyl acetates and arylboroxines/PhZnCl has been developed via Ni catalysis. Alkenyl acetates could be well-differ-entiated from aryl acetates (see scheme). This reliable method provides a convenient pathway to construct polysubstituted styrene derivatives.
- Sun, Chang-Liang,Yang, Wang,Xiao, Zhou,Wu, Zhen-Hua,Li, Bi-Jie,Guan, Bing-Tao,Shi, Zhang-Jie
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supporting information; experimental part
p. 5844 - 5847
(2010/09/03)
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- Nickel-catalyzed efficient and practical Suzuki-Miyaura coupling of alkenyl and aryl carbamates with aryl boroxines
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(Figure Presented) Suzuki-Miyaura coupling of unactivated alkenyl carbamates Is described to construct polysubstituted olefins. The developed process is also suitable for heteroaromatic and even electron-rich aromatic carbamates.
- Xu, Li,Li, Bi-Jie,Wu, Zhen-Hua,Lu, Xing-Yu,Guan, Bing-Tao,Wang, Bi-Qin,Zhao, Ke-Qing,Shi, Zhang-Jie
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supporting information; experimental part
p. 884 - 887
(2010/04/29)
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- Atom-efficient vinylic arylations with triarylbismuths as substoichiometric multicoupling reagents under palladium catalysis
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The first atom-efficient arylation of vinylic iodides was achieved by using triarylbismuths as substoichiometric multicoupling reagents under palladium catalysis. Vinylic iodides were efficiently coupled with electronically divergent triarylbismuths to furnish the corresponding arylated products in short reaction times.
- Rao, Maddali L.N.,Jadhav, Deepak N.,Venkatesh, Varadhachari
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experimental part
p. 4300 - 4306
(2011/02/24)
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- FeCl3-catalyzed intramolecular hydroarylation of alkynes
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The intramolecular hydroarylation of alkynes using a substoichiometric amount of FeCl3 is described. When starting from tetrasubstituted substrates, products resulting from an unexpected toluene (or xylene) elimination are isolated in good yields.
- Dal Zotto, Christophe,Wehbe, Johny,Virieux, David,Campagne, Jean-Marc
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scheme or table
p. 2033 - 2035
(2009/04/07)
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- Intramolecular cycloisomerization of aryl-substituted alkylidenecyclopropanes via NHC palladium-catalyzed cascade C-C bond cleavage/C-H activation/C-C bond formation
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A well-defined N-heterocyclic carbene (NHC) palladium-catalyzed intramolecular cyclization reaction of aryl-substituted alkylidenecyclopropanes (ACP) to 1-aryl dihydronaphthalenes is described. The NHC salts were found to suppress β-hydride elimination from the homoallylpalladium intermediate, which may lead to unwanted alkene formation. A plausible mechanism for the cycloisomerization was proposed. Georg Thieme Verlag Stuttgart.
- Yang, Yewei,Huang, Xian
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experimental part
p. 1366 - 1370
(2009/04/06)
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- Iodine induced transformations of alcohols under solvent-free conditions
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Iodine has been shown to be an efficient catalyst for transformations of alcohols under solvent-free conditions. In the presence of 5% of iodine, tertiary alcohols underwent dehydration forming the corresponding alkenes, while in the case of 2-phenylpropane-2-ol cyclodimerisation to 1,1,3-trimethyl-3-phenylindane took place. Secondary and primary benzyl alcohols under the same conditions gave the corresponding ethers.
- Stavber, Gaj,Zupan, Marko,Stavber, Stojan
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p. 8463 - 8466
(2007/10/03)
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- Synthesis and biological properties of 2-hydroxy-1-(1-phenyltetralyl) piperidine and some of its intermediates as derivatives of phencyclidine
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Phencyclidine (1-(1-phenylcyclohexyl)piperidine, CAS 956-90-1, PCP) has shown analgesic effects. Some of its derivatives were synthesized and their biological properties were studied. To date, only saturated ketones have been used as starting materials fo
- Ahmadi, Abbas,Mahmoudi, Ali
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p. 528 - 532
(2007/10/03)
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- Dynamic kinetic resolution-asymmetric transfer hydrogenation of 1-aryl-substituted cyclic ketones
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A range of 1-aryl-2-tetranols, and 1-phenyl-2-indanol, have been generated in high yield and enantiomeric excess from the corresponding racemic ketones, via a dynamic kinetic resolution-transfer hydrogenation process, using Ru(II)-TsDPEN in formic acid/triethylamine (5:2). This provides a potential entry to an asymmetric total synthesis of benzazepines such as Sch 39166.
- Alcock, Nathaniel J.,Mann, Inderjit,Peach, Philip,Wills, Martin
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p. 2485 - 2490
(2007/10/03)
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- Palladium-catalyzed cross coupling of Grignard reagents with in situ-derived enol phosphates
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A useful, one-pot protocol has been developed for the conversion of enolizable ketones to alkylated or arylated olefins by Pd-catalyzed cross coupling of in situ-generated enol phosphate intermediates with Grignard reagents.
- Miller, Joseph A.
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p. 7111 - 7114
(2007/10/03)
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- Kinetics and equilibrium constants for reactions of α-phenyl- substituted cyclopropylcarbinyl radicals
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Laser-flash photolysis methods were used to determine Arrhenius functions for cyclizations of the 4,4-diphenyl-3-butenyl (2) and trans-4- phenyl-3-butenyl (5) radicals to the 1,1-diphenylcyclopropylcarbinyl (1) and 1-phenylcyclopropylcarbinyl (4) radicals, respectively. At 20 °C, the cyclization rate constants are 1.7 x 107 and 5.4 x 106 s-1. Equilibrium constants for the two processes were estimated and evaluated with thermochemical data and via computational methods, and Arrhenius functions for the ring-opening reactions of the cyclopropylcarbinyl radicals were calculated. The cyclization reactions of 2 and 5 are strongly enthalpy controlled. Production of radicals 1 and 2 from the corresponding tert- butylperoxy esters in the presence of Et3SnH gave diphenylcyclopropylmethane and 1,1-diphenyl-1-butene from H-atom trapping of radicals 1 and 2 and 4- phenyl-1,2-dihydronaphthalene which derives from the product radical formed by addition of the radical moiety in 2 to the cis-phenyl group. Rate constants for the latter cyclization of 2 and for reactions of radicals 1 and 2 with Et3SnH were obtained from the indirect kinetic studies.
- Halgren, Thomas A.,Roberts, John D.,Horner, John H.,Martinez, Felix N.,Tronche, Christopher,Newcomb, Martin
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p. 2988 - 2994
(2007/10/03)
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- A concise synthesis of 1-substituted-2-tetralones by selective diol dehydration leading to ketone transposition
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Dehydration of 1-substituted-1,2-tetralindiols with zinc iodide afforded the corresponding 2-tetralones in excellent yields. This procedure was found to be superior to the more conventional BF3-catalyzed rearrangement of 1-substituted-1,2-epoxytetralins. (C) 2000 Elsevier Science Ltd.
- Jensen,Slobodzian
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p. 6029 - 6033
(2007/10/03)
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- Zeolite as a reagent and as a catalyst: Reduction and isomerization of alkenes by Ca Y
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Depending on the number of Bronsted acid sites present, Ca Y can act either as a reagent and reduce stilbenes to 1,2-diarylethanes or act as a catalyst and isomerize cis-stilbenes to the more stable trans form; Lewis acid sites generated by the activation process yield radical cations from stilbenes but these do not yield any stable products.
- Pitchumani,Joy, Abraham,Prevost, Nicolette,Ramamurthy
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p. 127 - 128
(2007/10/03)
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- Synthesis and Pharmacological Evaluation of 1-Phenyl-3-amino-1,2,3,4-tetrahydronaphthalenes as Ligands for a Novel Receptor with ?-like Neuromodulatory Activity
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Certain novel 1-phenyl-3-amino-1,2,3,4-tetrahydronaphthalenes (1-phenyl-3-aminotetralins, PATs) produced stimulation (ca. 30percent above basal levels) of tyrosine hydroxylase (TH) activity at 0.1 μM concentrations in rodent brain tissue. This effect on T
- Wyrick, Steven D.,Booth, Raymond G.,Myers, Andrew M.,Owens, Constance E.,Kula, Nora S.,et al.
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p. 2542 - 2551
(2007/10/02)
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- Photoinduced Nucleophilic Addition of Ammonia and Alkylamines to Aryl-Substituted Alkenes in the Presence of p-Dicyanobenzene
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The photoamination of 1,1-diphenylpropene (1a) with ammonia and some primary alkylamines in the presence of p-dicyanobenzene gave the corresponding N-substituted 2-amino-1,1-diphenylpropane (2a-e) along with the formation of 3-methyl-4,4-diphenylbutanenitrile (3a), 1,1-diphenylpropane (4a), 3,3-diphenylpropene (5), and diphenylmethane (6).In the case of 1,1-diphenylethene (1b), N-substituted 1-amino-2,2-diphenylethane (2f-h), 4,4-diphenylbutanenitrile (3b), and 1,1-diphenylethane (4b) were produced.In photoamination with t-butylamine in acetonitrile, 3a and 3b were mainly formed as a consequence of the incorporation of acetonitrile to 1a and 1b.The photoamination of 1-phenyl-3,4-dihydronaphthalene (1c) with isopropylamine or t-butylamine gave cis- and trans-N-substituted 1-phenyl-2-amino-1,2,3,4-tetrahydronaphthalenes (15 and 16) in a ratio of ca. 8:2.The mechanism of photoamination is discussed in terms of a photochemical electron transfer of 1 to p-dicyanobenzene followed by a nucleophilic addition of the amine to the cation radical of 1.
- Yamashita, Toshiaki,Shiomori, Koichiro,Yasuda, Masahide,Kensuke, Shima
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p. 366 - 374
(2007/10/02)
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- The Metal-Ammonia Reduction of Mono- and Dinaphtylbenzenes
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The metal-ammonia reduction of 1- and 2-phenylnaphthalene (9 and 10, respectively), 1,3-bis(1-naphthyl)benzene (5), 1,3-bis(2-naphthyl)benzene (6), 1,4-bis(1-naphthyl)benzene (7), and m-quinquephenyl (8) has been investigated. 9 affords a mixture of isomeric dihydro products together with 1-phenyl-1,2,3,4-tetrahydronaphthalene, and the effect of metal, temperature, and quenching methods on the product distribution is reported. 10 provided only a single dihydro (1,4-)isomer plus a tetrahydro product. both 5 and 7 provided a number of dihydro, tetrahydro, hexahydro, and octahydro products.On the other hand, 6 afforded high yields of a single tetrahydro product with lithium, and exclusively an octahydro product when 5-7 mol of sodium was used.In contrast to the terphenyls, which seem to have a propensity for inner-ring reduction, none of the naphthyl benzenes showed any tendency to reduce in the central benzene ring. m-Quinquephenyl reduced in two rings with no evidence for reduction in the central or outer rings.
- Marcinow, Zbigniew,Rabideau, Peter W.
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p. 3812 - 3816
(2007/10/02)
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- Rhodium-catalyzed C-C coupling reactions involving ring opening of strained molecules. II. Addition to olefins and aromatic substitution
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Rhodium-catalyzed C-C coupling reactions, involving ring opening of strained molecules, have been studied using diphenylmethylenecyclopropanes as models.It has been established that, as rhodium takes control of the ring opening process, activated olefins
- Chiusoli, Gian Paolo,Costa, Mirco,Melli, Luca
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p. 495 - 506
(2007/10/02)
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- Steric Effects. Internal Rotation of 1-Aryl-8-phenylnaphthalenes
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A general, albeit low-yielding, synthesis of 1-aryl-8-phenylnaphthalenes was devised and used to prepare three 1-(3'-X-5'-isopropylphenyl)-8-phenylnaphthalenes (X = H, F, Br).Activation parameters for the rotation of the 3'-X-5'-isopropylphenyl group were
- Cosmo, Robert,Sternhell, Sever
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p. 1107 - 1126
(2007/10/02)
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- Novel Coupling of Dithioacetals with Grignard Reagents
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Dithioacetals react with Grignard reagents in the presence of a catalytic amount of to give the corresponding olefinic coupling products in good yields: a mechanism for the reaction is suggested.
- Ni, Zhi-Jie,Luh, Tien-Yau
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p. 1515 - 1517
(2007/10/02)
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- PHOTOLYSIS OF CYCLIC ARYLVINYL HALIDES. FORMATION OF 1,2-BENZO-1,3-CYCLOALKADIENYL CATIONS AND THEIR REARRANGEMENTS
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Photolysis of 1,2-benzo-1,3-cycloalkadien-4-yl bromides and 1,2-benzo-1,3-cycloalkadien-3-yl chlorides showed a remarkable effect of ring size on the rearrangements of the resulting 1,2-benzo-1,3-cycloalkadienyl cations, i.e., 1,2-aryl or alkyl migration across the double bond and 1,2-hydride or methyl migration to the cationic center.
- Kitamura, Tsugio,Muta, Tomonobu,Tahara, Toru,Kobayashi, Shinjiro,Taniguchi, Hiroshi
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p. 759 - 762
(2007/10/02)
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- Thermolysis of Phenyl-substituted 1,2-Dihydronaphthalenes. Evidence for Diphenylbutadienes as Intermediates
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The thermal rearrangement of the four phenyl-substituted 1,2-dihydronaphthalenes (15), (16), (19), and (20) have been studied by flash vacuum pyrolysis (FVP).By using the deuteriated starting compounds -(15) and -(16), it has been established that 1- and 4-phenyl-1,2-dihydronaphthalene (15) and (19) and 2- and 3-phenyl-1,2-dihydronaphthalene (16) and (20) are interconverted via the intermediates 1- and 2-phenyl-2,3-dihydronaphthalene (17) and (18), respectively, through two consecutive, sigmatropic 1,5-hydrogen shifts.In both processes partial oxidation to the corresponding phenylnaphthalenes (21) and (22) takes place.The deuterium distribution in the pyrolysis products suggests that in the hot zone diphenylbutadienes are formed, which are reconverted into phenyldihydronaphthalenes upon reaching the cold receiving flask.By FVP of 4-(p-tolyl)-1,2-dihydronaphthalene (34), 1-phenyl-1-(p-tolyl)butadiene (39), and 1-phenyl-4-(p-tolyl)butadiene (45) the latter type of interconversion could be confirmed.
- Lamberts, Joseph J. M.,Cuppen, Theo J. H. M.,Laarhoven, Wim H.
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p. 1819 - 1828
(2007/10/02)
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- Thermochemistry of Phenyl-Substituted Benzobicyclohex-2-enes
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The thermal rearrangements of benzobicyclohex-2-ene (21) and its phenyl-substituted analogues 22-25 (Scheme V) as models of sterically constrained phenylcyclopropanes have been studied by means of flash vacuum pyrolysis.In most cases the major pathway was cleavage of the "internal" C(1)-C(5) cyclopropane bond followed by a 1,2-hydrogen or a 1,2-phenylshift in the resulting biradical.For 6-phenylbenzobicyclohex-2-ene (25), substantial cleavage of the "external" C(1)-C(6) cyclopropane bond was observed, the phenyl substitution pattern being favorable for stabilization of the resulting biradical 62.Phenyl-substituted 1,2-dihydronaphthalenes 44, 47, 51, and 55 are among the major products.Comparison of the plots of the pyrolysis product composition of the 1,2-dihydronaphthalenes vs. pyrolysis temperature with similar plots of the title compounds (22-25) suggested that some of the minor products, viz., the 1,2-divinylbenzenes 31, 42, and 49, are formed via carbenes 30, 41, 50, 57, and 61 rather than via biradicals.Especially at higher pyrolysis temperatures, a large amount of an oxidation product, viz., 1- or 2-phenylnaphthalene (48 or 54), is formed.
- Lamberts, Joseph J.,Laarhoven, Wim H.
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p. 100 - 106
(2007/10/02)
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- BENZO- AND INDOLOQUINOLIZIDINE DERIVATIVES XIX. THE SYNTHESIS AND PHARMACOLOGICAL ACTIVITY OF SOME QUINOLIZIDINE DERIVATIVES, ANALOGUES OF BUTACLAMOL
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Indenopyridoisoquinoline and benzopyridophenanthridine derivatives were synthesized as the conformationally rigid analogues of butaclamol.For both series, a unique reaction scheme has been worked out in order to obtain the desired trans-cisoid-cis conform
- Laus, G.,Tourwe, D.,Binst, G. Van
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p. 311 - 331
(2007/10/02)
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- Photochemistry of Phenyl-Substituted Benzobicyclohex-2-enes. A Reverse Di-?-methane Rearrangement
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The photochemical rearrangements of phenyl-substituted benzobicyclohex-2-enes can generally be explained by assuming that homolytic fission of that cyclopropane bond which leads to the most stable diradical is the primary step.The final products are formed by 1,2 hydrogen shifts in the intermediate.An exception to this general pattern was observed with 5-phenylbenzobicyclohex-2-ene (5).The photoproducts of 5 could only be explained by assuming reverse di-?-methane rearrangements followed by 1,3 hydrogen shifts.It is argued that this reaction path is followed because of the high rate to the back-reaction of the homolytic bond fission of 5.
- Lamberts, Joseph J. M.,Laarhoven, Wim H.
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p. 2202 - 2206
(2007/10/02)
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- The synthesis of bridged biphenyl and naphthyl compounds by the photolytic and thermal extrusion of SO2
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The photolytic and flash vacuum thermolytic behavior of several SO2-containing cyclic compounds was studied.The expulsion of SO2 by flash vacuum thermolysis afforded the corresponding bridged compounds in high yield.
- Harpp, David N.,Mullins, Dennis F.
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p. 757 - 761
(2007/10/02)
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- Anomalous Acetoxylation of Aromatic Nuclei: Some Structural Requirements in the Substrate
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For certain aromatic nuclei, bromination in acetic acid in the presence of pyridine is accompanied by nuclear acetoxylation.As first observed with galbulin, when two alkoxyl groups, one meta and one para to a benzylic centre of the substrate are present, acetoxylation occurs at the intervening ortho position.Under the given conditions, acetoxylation occurs at position 8 of 6,7-dimethoxy-1-phenyl-1,2,3,4-tetrahydronaphthalene, and at position 2 of 3,4-dimethoxy diphenyl and triphenyl-methanes.Acetoxylation does not occur in the absence of either of the alkoxy groups or in the absence of pyridine, not does it occur in the pendant ring of 1-(3',4'-dimethoxyphenyl)-1,2,3,4-tetrahydronaphthalene.These results are consistent with the earlier suggestion that the reaction occurs by way of initial oxidative formation of a doubly benzylic cation
- Bandaranayake, Wickramasinghe M.,Riggs, Noel V.
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p. 115 - 129
(2007/10/02)
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