- Aryloxymethyltrifluoroborates for Rhodium-Catalyzed Asymmetric Conjugate Arylation. o-Methoxyarylation through 1,4-Rhodium Shift
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Reaction of potassium aryloxymethyltrifluoroborates 1 with α,β-unsaturated carbonyl compounds 2 in the presence of a chiral diene-rhodium catalyst in H2O at 100 °C introduced 2-methoxyaryl groups at the β-position of 2 with high enantioselectiv
- Ming, Jialin,Hayashi, Tamio
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- Palladium-Catalyzed Regioselective C–H Acetoxylation of 2-Aryloxypyridines with 2-Pyridyloxy as a Removable Directing Group
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A simple and regioselective palladium-catalyzed ortho-C(sp2)–H acetoxylation of 2-aryloxypyridines with PhI(OAc)2as both the oxidant and acetate source has been developed. The mono- and di-acetoxylated products can be achieved by tuning the equivalents of PhI(OAc)2and the reaction temperature. A wide range of 2-aryloxypyridines is tolerated. Moreover, 2-pyridyloxyl and acetyl groups can be easily removed, which provides straightforward access to poly-substituted phenols.
- Wang, Liang,Pan, Liang,Huang, Yibo,Chen, Qun,He, Mingyang
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supporting information
p. 3113 - 3118
(2016/07/12)
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- Pd(II) catalyzed ortho C-H iodination of phenylcarbamates at room temperature using cyclic hypervalent iodine reagents
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A novel approach to access ortho iodinated phenols using cyclic hypervalent iodine reagents through palladium(II) catalyzed C-H activation has been developed through weak coordination. The reaction showed excellent regioselectivity, reactivity and good functional group tolerance. A unique mechanism was proposed.
- Sun, Xiuyun,Yao, Xia,Zhang, Chao,Rao, Yu
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supporting information
p. 10014 - 10017
(2015/06/22)
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- Intramolecular Direct Arylation of 3-Halo-2-pyrones and 2-Coumarins
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Direct arylation represents a favorable alternative to traditional cross-coupling and has found widespread use with simple aryls and robust heterocycles. Herein a direct arylation protocol has been optimized and applied to 2-pyrones, which are delicate an
- Nolan, Marie-T.,Pardo, Leticia M.,Prendergast, Aisling M.,McGlacken, Gerard P.
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p. 10904 - 10913
(2015/11/18)
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- Room-temperature Pd-catalyzed C-H chlorination by weak coordination: One-pot synthesis of 2-chlorophenols with excellent regioselectivity
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A room-temperature Pd(ii)-catalyzed regioselective chlorination reaction has been developed for a facile one-pot synthesis of a broad range of 2-chlorophenols. The reaction demonstrates an excellent regioselectivity and reactivity for C-H chlorination. This reaction represents one of the rare examples of mild C-H functionalization at ambient temperature.
- Sun, Xiuyun,Sun, Yonghui,Zhang, Chao,Rao, Yu
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supporting information
p. 1262 - 1264
(2014/02/14)
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- Intramolecular annulation of aromatic rings with N-sulfonyl 1,2,3-triazoles: Divergent synthesis of 3-methylene-2,3-dihydrobenzofurans and 3-methylene-2,3-dihydroindoles
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The controllable synthesis of 3-methylene-2,3-dihydrobenzofurans 2 and 3-methylene-2,3-dihydroindoles 5 has been developed through Rh-catalyzed intramolecular annulation of aromatic rings with azavinyl carbenes. This journal is
- Tang, Xiang-Ying,Zhang, Yong-Sheng,He, Lv,Wei, Yin,Shi, Min
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supporting information
p. 133 - 136
(2015/01/09)
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- Palladium-catalyzed decarboxylative coupling of α-oxocarboxylic acids with C(sp2)-H of 2-aryloxypyridines
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An efficient palladium-catalyzed decarboxylative ortho-acylation of 2-aryloxypyridines with α-oxocarboxylic acids is described. In this new transformation, the aromatic C(sp2)-H bond was successfully acylated to give diverse aromatic ketones regioselectively in moderate to good yields. The pyridine group can be removed easily after the acylation to give the corresponding 2-hydroxy aromatic ketones. Copyright
- Yao, Jinzhong,Feng, Ruokun,Wu, Zaihong,Liu, Zhanxiang,Zhang, Yuhong
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supporting information
p. 1517 - 1522
(2013/06/27)
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- Hydroxy- and aminophenyl radicals from arenediazonium salts
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Arenediazonium salts are well-known sources of aryl radicals; however, the hydroxy- and amino-substituted derivatives 1, 2, and 3, which lead to the respective formation of radicals 4, 5, and 6, have rarely been employed in synthetic organic chemistry so far. New synthetic applications of these species have been found, and the properties that may have previously hindered their successful use have been investigated. Copyright
- Pratsch, Gerald,Anger, Christian A.,Ritter, Katharina,Heinrich, Markus R.
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body text
p. 4104 - 4108
(2011/05/12)
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- Ketonization equilibria of phenol in aqueous solution
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The two keto tautomers of phenol (1), cyclohexa-2,4-dienone (2) and cyclohexa-2,5-dienone (3), were generated by flash photolysis of appropriate precursors in aqueous solution, and the pH-rate profiles of their enolization reactions, 2 → 1 and 3 → 1, were measured. The rates of the reverse reactions, 1 → 2 and 1 → 3, were determined from the rates of acid-catalyzed hydron exchange at the ortho- and para-positions of 1; the magnitude of the kinetic isotope effect was assessed by comparing the rates of hydrogenation of phenol-2t and -2d. The ratios of the enolization and ketonization rate constants provide the equilibrium constants of enolization, pKE(2, aq, 25°C) = -12.73 ± 0.12 and pKE(3, aq, 25°C) = -10.98 ± 0.15. Combination with the acidity constant of phenol also defines the acidity constants of 2 and 3 through a thermodynamic cycle. These ketones are remarkably strong carbon acids: pKa(2) = -2.89 ± 0.12 and pKa(3) = -1.14 ± 0.15. They disappear by proton transfer to the solvent with lifetimes, τ(2) = 260 μs and τ(3) = 13 ms, that are insensitive to pH in the range from 3-10.
- Capponi, Marco,Gut, Ivo G.,Hellrung, Bruno,Persy, Gaby,Wirz, Jakob
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p. 605 - 613
(2007/10/03)
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- Gas-phase oxygenation of benzene derivatives around 300 K with O(3P) atoms produced by microwave discharge of N2O. Part 2. Kinetic H/D isotope effects.
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The possible pathways for the formation of (chloro)phenol, following the addition of O(3P) to (chloro)benzene, have been examined using deuterated substrates: C6D6 (also in admixture with C6H6) and p-deuterochlorobenzene.Whereas with O-C6H6 adduct biradicals, loss of H* to give phenoxy radicals predominates, only one-third of the O-C5D6 intermediates undergo the corresponding reaction.Phenoxy radicals lead to phenol by transfer of an H(D) atom from cyclohexadienyl-type radicals, formed from H* (D*) and substrate.Analogously, in reactions of p-deuterochlorobenzene, loss of H is a major reaction after addition of an oxygen atom to a meta position, whereas loss of D (to give p-chlorophenol) occurs only with 35percent of the corresponding O(3P) adduct biradicals.The isotopic composition of phenol formed from p-DC6H4Cl (via p-DC6H4O*; generated by ipso substitution) revealed that H transfer to phenoxy radicals primarily gives the keto tautomers as major products.Isomerization of (chloro)benzene-O(3P) adduct biradicals to the corresponding phenols also appears to involve mainly, keto tautomers.The reaction of O(3P) with p-deuterochlorobenzene showed a slight change in the o/m/p distribution; this can be explained by the absence of a net secondary H/D isotope effect for O(3P) addition to the para site and a normal secondary isotope effect for meta addition.
- Sol, Veronica M.,Louw, Robert,Mulder, Peter
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p. 346 - 352
(2007/10/02)
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- Reductive Dechlorination of Chloro-phenols and -benzoic acids by Raney Co-Al Alloy in an Alkaline Deuterium Oxide Solution and Preparation of Deuterated Salicylic Acids
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Reduction of monochloro-phenols (1a-c) and -benzoic acids (3a-c) by using Raney Co-Al alloy in 10percent NaOD-D2O gave phenols (2a-c) and benzoic acids (4a-c) in 86-93percent isotopic purities.The reduction of di-, tri-, and tetra-chlorinated derivatives, (1) and (3), gave the deuteriated products, (2) and (4), in somewhat low isotopic purities (70-84percent).In the reduction of polychlorinated benzoic acids (3), the use of a mixed solution (1/1 = v/v) of 10percent Na2CO3-D2O and 10percent NaOD-D2O was effective and gave 4 in 80-89percent isotopic purities.The treatment of chlorosalicylic acids (5) with Raney Co-Al alloy in 10percent NaOD-D2O gave 1> (6) - 3> (6) in 91-93percent isotopic purities.
- Tashiro, Masashi,Tsuzuki, Hirohisa,Matsumoto, Jun-ichi,Mataka, Shuntaro,Nakayama, Kouji,et al.
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p. 2826 - 2851
(2007/10/02)
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