- Annelated Pyridine Bases for the Selective Acylation of 1,2-Diols
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A set of 24 annelated derivatives of 4-diaminopyridine (DMAP) has been synthesized and tested with respect to its catalytic potential in the regioselective acylation of 1,2-diol substrates. The Lewis basicities of the catalysts as quantified through quantum chemical calculations vary due to inductive substituent effects and intramolecular stacking interactions between side chain π-systems and the pyridinium core ring system. The primary over secondary hydroxyl group selectivities in catalytic acylations of 1,2-diol substrates depend on the size and the steric demand of the Lewis base and the anhydride reagent.
- Mayr, Stefanie,Zipse, Hendrik
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- Visible-Light-Induced Arene C(sp 2)-H Lactonization Promoted by DDQ and tert -Butyl Nitrite
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A visible-light photocatalytic aerobic oxidative lactonization of arene C(sp 2)-H bonds proceeds in the presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tert -butyl nitrite (TBN). Under the optimized conditions, a range of 2-arylbenzoic acids is converted into the corresponding benzocoumarin derivatives in moderate to excellent yields. This method is characterized by its atom economy, mild reaction conditions, the use of a green oxidant and metal-free catalysis.
- Chen, Bajin,Hu, Baoxiang,Hu, Xinquan,Jin, Liqun,Li, Meichao,Shen, Zhenlu,Sun, Nan,Wang, Shengpeng,Wang, Yiqing
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supporting information
p. 261 - 266
(2020/02/18)
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- Exploration of Biaryl Carboxylic Acids as Proton Shuttles for the Selective Functionalization of Indole C-H Bonds
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A survey of diversely substituted 2-arylbenzoic acids were synthesized and tested for use as proton shuttle in the direct arylation of indoles with bromobenzenes. It was found that 3-ethoxy-2-phenylbenzoic acid gives superior yield and selectivity for this class of substrates.
- Pi, Jing-Jing,Lu, Xiao-Yu,Liu, Jing-Hui,Lu, Xi,Xiao, Bin,Fu, Yao,Guimond, Nicolas
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p. 5791 - 5800
(2018/05/14)
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- Amide-Directed C?H Sodiation by a Sodium Hydride/Iodide Composite
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A new protocol for amide-directed ortho and lateral C?H sodiation is enabled by sodium hydride (NaH) in the presence of either sodium iodide (NaI) or lithium iodide (LiI). The transient organosodium intermediates could be transformed into functionalized aromatic compounds.
- Huang, Yinhua,Chan, Guo Hao,Chiba, Shunsuke
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supporting information
p. 6544 - 6547
(2017/05/29)
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- Electronic effects on the substitution reactions of benzhydrols and fluorenyl alcohols. Determination of mechanism and effects of antiaromaticity
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A range of substituted benzhydrols and fluorenols were prepared and subjected to acid catalysed methanolysis. Analysis of the rates of each of these processes showed correlation with Hammett σ+ parameters as is consistent with the significant build-up of positive charge adjacent to the ring. In combination with the similarity of the electronic susceptibility of the processes, these data suggest that both reactions proceed through a unimolecular rate-determining step. This shows that the effect of fusion of the phenyl systems (and hence potentially introducing an antiaromatic carbocation intermediate) is only to slow the rate of reaction rather than change the mechanism of the process.
- George, Stephen R. D.,Elton, Timothy E.,Harper, Jason B.
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supporting information
p. 10745 - 10750
(2015/11/17)
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- Synthesis of fluorenones through rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids
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An efficient approach to the synthesis of fluorenones via the rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids was developed. Using this procedure, fluorenones with various substituents can be synthesized in good to high yields. This work marks the first recorded use of catalytic intramolecular acylation to synthesize fluorenones.
- Fukuyama, Takahide,Maetani, Shinji,Miyagawa, Kazusa,Ryu, Ilhyong
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supporting information
p. 3216 - 3219
(2014/07/08)
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- An improved protocol for ligandless Suzuki-Miyaura coupling in water
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Using a reverse order of addition of reagents, PdCl2 and Pd(OAc)2 are efficient catalysts for the Suzuki-Miyaura reactions in water. The ligandless and mild conditions, the high stability of the catalytic system, short reaction time and good to excellent yields are important features of this protocol.
- Korolev, Dmitrii N.,Bumagin, Nikolay A.
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p. 4225 - 4229
(2007/10/03)
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- Pd-EDTA as an efficient catalyst for Suzuki-Miyaura reactions in water
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PdCl2-EDTA complex 1 is an efficient catalyst for the Suzuki-Miyaura reactions of aryl and heteroaryl halides with aryl(heteroaryl)boronic acids in water at 20-100°C. Aryl iodides and bromides undergo the cross-coupling with turnover numbers (T
- Korolev, Dmitrii N.,Bumagin, Nikolay A.
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p. 5751 - 5754
(2007/10/03)
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- Hypervalent iodine in synthesis XL: First example of palladium-catalyzed coupling reaction of 1-hydroxy-1,2-benziodoxol-3(1H)-one with arylboronic acids and arylborates
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Biaryl-2-carboxylic acids have been prepared by palladium-catalyzed coupling reaction of 1-hydroxy-1,2-benziodoxol-3(1H)-one with arylboronic acids and arylborates with good yields under mild conditions.
- Xia, Min,Chen, Zhenchu
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- Synthesis and characterization of orally active nonpeptide vasopressin V2 receptor antagonists
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The present study was undertaken to evaluate whether a novel series of 2,6-diaza-5-oxobicyclo[5.4.0]undeca-1(7),8,10-triene derivatives exhibited antagonistic activity for vasopressin V1 and V2 receptors. Most of these compounds were
- Ohkawa, Takehiko,Zenkoh, Tatsuya,Tomita, Masayuki,Hosogai, Naomi,Hemmi, Keiji,Tanaka, Hirokazu,Setoi, Hiroyuki
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p. 501 - 510
(2007/10/03)
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- Nonpeptide arginine vasopressin antagonists for both V(1A) and V2 receptors: Synthesis and pharmacological properties of 2-Phenyl-4'- [(2,3,4,5-tetrahydro-1H-1-benzazepin-1-yl)carbonyl]benzanilide derivatives
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A series of compounds structurally related to 4'-[(2,3,4,5-tetrahydro- 1H-1-benzazepin-1-yl)carbonyl]benzanilide was synthesized and demonstrated to have arginine vasopressin (AVP) antagonist activity for both V(1A) and V2 receptors. The introduction of a phenyl or a 4-substituted phenyl group into the ortho position of the benzoyl moiety resulted in an increase in both binding affinity and antagonistic activity. The 2-(4-methylphenyl) derivative (1g) exhibited high antagonistic activities for both V(1A) (8.6- fold) and V2 (38-fold) receptors and high oral activity (8.6-fold) compared with the 2-methyl lead compound (1a). Detail of the synthesis and the pharmacological properties of this series are presented.
- Matsuhisa, Akira,Tanaka, Akihiro,Kikuchi, Kazumi,Shimada, Yoshiaki,Yatsu, Takeyuki,Yanagisawa, Isao
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p. 1870 - 1874
(2007/10/03)
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- Intramolecular reactivity of arylcarbenes: Biphenyl-2-ylcarbenes
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Biphenyl-2-ylcarbenes, 2-ArC6H4CR, were generated photolytically and thermally from diazo precursors. Cyclization, leading to fluorenes, competes with capture of the carbenes by methanol but proceeds faster than intramolecular hydrogen shifts (with R = Me) and intermodular C - H insertion reactions (with R = H in cyclohexane). By comparison of product ratios with kinetic data for related carbenes from the literature, the cyclization rate is estimated as ca 1011 s-1. The intramolecular reactivity of biphenyl-2-ylcarbenes is not significantly attenuated by variation of R (R = H, Me, Ph). Very minor effects of triplet sensitization and methanol quenching indicate that fluorenes arise from spin-equilibrated biphenyl-2-ylcarbenes, presumably from the singlet state. When Ar = mesityl, the carbene predominantly inserts into C - H bonds of the 2′-methyl groups, giving rise to a dihydrophenanthrene. Formation of a fluorene derivative, by formal insertion into C - C bonds, occurs as a minor process. This unprecedented reaction points to intervention of an o-xylylene in which the methyl group migrates. Laser flash photolysis (LFP) of 2-PhC6H4CN2Ph generates a transient absorption which is due to the T0→Tn transition of 9-phenylfluorene rather than to the presumed o-xylylene. On LFP of 2-ArC6H4CN2Ph in trifluoroethanol-acetonitrile, protonation of the carbenes gives rise to carbocations, 2-ArC6H4CH+Ph. The transient absorption spectra of these cations are strongly influenced by twisting about the Ar - Ar bond (Ar = Ph 4.
- Dorra, Michael,Gomann, Klaus,Guth, Michael,Kirmse, Wolfgang
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p. 598 - 610
(2007/10/03)
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- Convenient Synthesis of Biphenyl-2-carboxylic Acids via the Nucleophilic Aromatic Substitution Reaction of 2-Methoxybenzoates by Aryl Grignard Reagents
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Nucleophilic aromatic substitution (SNAr) of 2-methoxybenzoic esters derived from 2,6-dialkylphenols by aryl Grignard reagents affords 1,1'-biphenyl-2-carboxylates in excellent yields by proper choice of the bulk of the 2,6-dialkyl-substituents. The phenoxyl protecting groups can be easily removed from the resulting biphenyl-2-carboxylates to the free acids by treatment with potassium hydroxide in aqueous ethanol (2,4,6-trimethylphenyl and 2,6-diisopropylphenyl esters) or sodium methoxide in toluene-hexamethylphosphoric triamide (2,6-di-t-butyl-4-methylphenyl esters). The regioselective biphenyl coupling reaction via the SNAr process is utilized for the key-step construction of the biphenyl skeleton in a formal synthesis of cannabinol.
- Hattori, Tetsutaro,Suzuki, Takatsugu,Hayashizaka, Noriyuki,Koike, Nobuyuki,Miyano, Sotaro
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p. 3034 - 3040
(2007/10/02)
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