- Room Temperature Coupling of Aryldiazoacetates with Boronic Acids Enhanced by Blue Light Irradiation
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A visible-light-promoted photochemical protocol is reported for the coupling of aryldiazoacetates with boronic acids. This photochemical reaction shows great enhancement compared to the same protocol performed in the absence of light. Except for a few cases, the room temperature coupling in the dark (thermal process) generally does not work. When it does, it is likely to also involve free carbenes as key intermediates. Alternatively, photochemical reactions show a broad scope, can be performed under air and tolerate a wide variety of functional groups. Reaction-evolution monitoring, DFT calculations and control experiments have been used to evaluate the main aspects of this intricate mechanistic scenario. Biologically active molecules Adiphenine, Benactyzine and Aprophen have been prepared as examples of synthetic applications.
- da Silva, Amanda F.,Afonso, Marco A. S.,Cormanich, Rodrigo A.,Jurberg, Igor D.
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supporting information
p. 5648 - 5653
(2020/04/22)
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- Harnessing Applied Potential: Selective β-Hydrocarboxylation of Substituted Olefins
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The construction of carboxylic acid compounds in a selective fashion from low value materials such as alkenes remains a long-standing challenge to synthetic chemists. In particular, β-addition to styrenes is underdeveloped. Herein we report a new electrosynthetic approach to the selective hydrocarboxylation of alkenes that overcomes the limitations of current transition metal and photochemical approaches. The reported method allows unprecedented direct access to carboxylic acids derived from β,β-trisubstituted alkenes, in a highly regioselective manner.
- Alkayal, Anas,Buckley, Benjamin R.,Malkov, Andrei V.,Montanaro, Stephanie,Tabas, Volodymyr,Wright, Iain A.
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supporting information
(2020/02/13)
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- Palladium(II)-Catalyzed C(sp2)-H Carbonylation of Sterically Hindered Amines with Carbon Monoxide
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A palladium-catalyzed, amine-directed C(sp2)-H carbonylation of α,α-disubstituted benzylamine under 1 atm of CO for the facile synthesis of sterically hindered benzolactam has been developed. The key to success is the use of 2,2,6,6-tetramethyl-1-piperidinyloxy as the crucial sole oxidant. The synthetic utility of this transformation has been demonstrated by the first concise synthesis of the natural product spiropachysin-20-one.
- Cheng, Xiu-Fen,Wang, Tao,Li, Yan,Wu, Yun,Sheng, Jie,Wang, Rui,Li, Chao,Bian, Kang-Jie,Wang, Xi-Sheng
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supporting information
p. 6530 - 6533
(2018/10/20)
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- Nickel-Catalyzed oxidative coupling of unactivated C(sp3)-H bonds in aliphatic amides with terminal alkynes
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In this work, we demonstrated Ni-catalyzed oxidative coupling of unactivated C(sp3)-H bonds with terminal alkynes for construction of C(sp3)-C(sp) bonds to synthesize alkyl-substituted internal alkynes. Different amides exhibited good compatibility. Preliminary mechanistic studies were conducted to account for this alkynylation.
- Luo, Fei-Xian,Cao, Zhi-Chao,Zhao, Hong-Wei,Wang, Ding,Zhang, Yun-Fei,Xu, Xing,Shi, Zhang-Jie
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supporting information
p. 18 - 21
(2017/04/04)
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- Nickel-catalysed direct alkylation of thiophenes via double C(sp3)-H/C(sp2)-H bond cleavage: The importance of KH2PO4
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A Ni-catalyzed oxidative C-H/C-H cross-dehydrogenative coupling (CDC) reaction was developed for constructing various highly functionalized alkyl (aryl)-substituted thiophenes. This method employs thiophenes and aliphatic (aromatic) amides that contain an 8-aminoquinoline as a removable directing group in the presence of a silver oxidant. The approach enables the facile one-step synthesis of substituted thiophenes with high functional group compatibility via double C-H bond cleavage without affecting C-Br and C-I bonds. DFT calculations verify the importance of KH2PO4 as an additive for promoting C-H bond cleavage and support the involvement of a Ni(iii) species in the reaction.
- Wang, Xie,Xie, Peipei,Qiu, Renhua,Zhu, Longzhi,Liu, Ting,Li, You,Iwasaki, Takanori,Au, Chak-Tong,Xu, Xinhua,Xia, Yuanzhi,Yin, Shuang-Feng,Kambe, Nobuaki
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supporting information
p. 8316 - 8319
(2017/07/26)
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- Site-Selective Catalytic Carboxylation of Unsaturated Hydrocarbons with CO2 and Water
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A catalytic protocol that reliably predicts and controls the site-selective incorporation of CO2 to a wide range of unsaturated hydrocarbons utilizing water as formal hydride source is described. This platform unlocks an opportunity to catalytically repurpose three abundant, orthogonal feedstocks under mild conditions.
- Gaydou, Morgane,Moragas, Toni,Juliá-Hernández, Francisco,Martin, Ruben
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supporting information
p. 12161 - 12164
(2017/09/12)
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- Bridging C?H Activation: Mild and Versatile Cleavage of the 8-Aminoquinoline Directing Group
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8-Aminoquinoline has emerged as one of the most powerful bidentate directing groups in history of C?H activation within the last decade. However, cleavage of its robust amide bond has shown to be challenging in several cases, thus jeopardizing the general synthetic utility of the method. To overcome this limitation, we herein report a simple oxidative deprotection protocol. This transformation rapidly converts the robust amide to a labile imide, allowing subsequent cleavage in a simple one-pot fashion to rapidly access carboxylic acids or amides as final products.
- Berger, Martin,Chauhan, Rajan,Rodrigues, Catarina A. B.,Maulide, Nuno
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supporting information
p. 16805 - 16808
(2016/11/16)
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- Hydrodecarboxylation of Carboxylic and Malonic Acid Derivatives via Organic Photoredox Catalysis: Substrate Scope and Mechanistic Insight
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A direct, catalytic hydrodecarboxylation of primary, secondary, and tertiary carboxylic acids is reported. The catalytic system consists of a Fukuzumi acridinium photooxidant with phenyldisulfide acting as a redox-active cocatalyst. Substoichiometric quantities of Hünigs base are used to reveal the carboxylate. Use of trifluoroethanol as a solvent allowed for significant improvements in substrate compatibilities, as the method reported is not limited to carboxylic acids bearing α heteroatoms or phenyl substitution. This method has been applied to the direct double decarboxylation of malonic acid derivatives, which allows for the convenient use of dimethyl malonate as a methylene synthon. Kinetic analysis of the reaction is presented showing a lack of a kinetic isotope effect when generating deuterothiophenol in situ as a hydrogen atom donor. Further kinetic analysis demonstrated first-order kinetics with respect to the carboxylate, while the reaction is zero-order in acridinium catalyst, consistent with another finding suggesting the reaction is light limiting and carboxylate oxidation is likely turnover limiting. Stern-Volmer analysis was carried out in order to determine the efficiency for the carboxylates to quench the acridinium excited state.
- Griffin, Jeremy D.,Zeller, Mary A.,Nicewicz, David A.
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supporting information
p. 11340 - 11348
(2015/09/21)
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- Direct lactonization of 2-arylacetic acids through Pd(II)-catalyzed C-H activation/C-O formation
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Palladium-catalyzed direct lactonization of 2-arylacetic acids through a reaction sequence that includes C-H activation/C-O formation is reported. This method provides a concise and efficient pathway to synthesize fully functionalized benzofuranone derivatives, which are highly relevant to bioactive natural and synthetic products.
- Yang, Mingyu,Jiang, Xingyu,Shi, Wen-Juan,Zhu, Qi-Lei,Shi, Zhang-Jie
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supporting information
p. 690 - 693
(2013/04/10)
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- Dirhodium(II) tetrakis[N-tetrafluorophthaloyl-(S)-tert-leucinate]: An exceptionally effective Rh(II) catalyst for enantiotopically selective aromatic C-H insertions of diazo ketoesters
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Dirhodium(II) tetrakis[N-tetrafluorophthaloyl-(S)-tert-leucinate], Rh2[(S)-TFPTTL]4, in which the phthalimido hydrogen atoms of the parent dirhodium(II) complex are substituted by fluorine atoms, dramatically enhances the reactivity and enantioselectivity (up to 97% ee) in intramolecular aromatic C-H insertion reactions of methyl 4-alkyl-2-diazo-4,4-diphenyl-3-oxopropionates. Catalysis with the use of 0.001 mol% of Rh2[(S)-TFPTTL]4 has achieved the highest turnover number (up to 98,000 with the methyl substituent) ever recorded for chiral dirhodium(II) complex-catalyzed carbene transformations, without compromising the yield or enantioselectivity of the process.
- Tsutsui, Hideyuki,Yamaguchi, Yukiko,Kitagaki, Shinji,Nakamura, Seiichi,Anada, Masahiro,Hashimoto, Shunichi
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p. 817 - 821
(2007/10/03)
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- Anticholinergics which may be used as medicaments as well as processes for preparing them
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The present invention relates to new anticholinergics of general formula 1 wherein A, X ? and the groups R1, R2, R3, R4, R5, R6 and R7 may have the meanings given in the claims and in the specification, processes for preparing them and their use as pharamaceutical compositions.
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- An efficient and general method for ester hydrolysis on the surface of silica gel catalyzed by indium triiodide under microwave irradiation
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Carboxylic esters are hydrolyzed to the corresponding carboxylic acids in high yields through a simple microwave assisted operation on the surface of silica gel moistened with few drops of water in presence of indium triiodide.
- Ranu,Dutta,Sarkar
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p. 4167 - 4171
(2007/10/03)
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- N-acyl sulfamic acid esters (or thioesters), N-acyl sulfonamides, and N-sulfonyl carbamic acid esters (or thioesters) as hypercholesterolemic agents
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The present invention is directed to compounds useful for the regulation of cholesterol of Formula I, methods for using them and pharmaceutical compositions thereof, STR1 wherein X and Y are oxygen, sulfur, or (CR'R")n wherein n is 1 to 4; R is hydrogen, alkyl, or benzyl; R1 and R2 are phenyl, substituted phenyl, naphthyl, substituted naphthyl, an aralkyl group, an alkyl chain, adamantyl, or a cycloalkyl group.
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- Molecular Modification of Anticholinergics as Probes for Muscarinic Receptors. Amino Esters of α-Substituted Phenylacetic Acid and Related Analogues
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Two series of compounds having the general structure of C6H5CRR'COOCH2CH2NEt2 were synthesized and examined for their antispasmodic activities.These compounds were selected as structural probes for exploring the nature of muscarinic cholinergic receptor binding sites that interact with atropine-like anticholinergics.These studies indicate a rather strict size limitation for the hydrophobic region of the receptor and suggest intramolecular hydrogen bonding as a possible means to explain the observed stereoselectivity.
- Lu, Mattias C.,Wung, Walley E.,Shih, Lisa B.,Callejas, Soledad,Gearien, James E.,Thompson, Emmanuel B.
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p. 273 - 278
(2007/10/02)
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- CARBOXYLATION OF ALCOHOLS WITH CARBON MONOXIDE SUPERSATURATED IN STRONG ACID. FACILE SYNTHESIS OF 2,2-BIS(4-HALOPHENYL)ACETIC, -PROPIONIC, AND RELATED ACIDS
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Using 97percent H2SO4 supersaturated with carbon monoxide, bis(4-halophenyl)methanols, 1,1-bis(4-halophenyl)ethanols and related alcohols were transformed to the carboxylic acids in 60-95percent yields.
- Takahashi, Yukio,Yoneda, Norihiko,Nagai, Hiroshi
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p. 1733 - 1734
(2007/10/02)
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- Carbanions. 23. Cleavage of 1,2-Diphenylethane and Derivatives by Cs-K-Na Alloy. Cometitive Rates of Bond Scission
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The following hydrocarbons are cleaved at a C-C bond to allylic and or/benzylic cesium compounds within 2 h by Cs-K-Na alloy in THF at -75 deg C: meso-2,3-diphenylbutane, 2,3-dimethyl-2,3-diphenylbutane, 1,2,2-triphenylpropane, 4-phenyl-1-butene, bibenzyl, and eight o-,m-, or p-methyl derivatives of bibenzyl.Under the same conditions 2-methyl- and 3-methyl-4-phenyl-1-butene were partially cleaved, 4,4'-dimethylbibenzyl was only slightly cleaved, and 9,10-dihydrophenanthrene was not detectably cleaved, while 10,11-dihydro-5H-dibenzocycloheptene underwent alternative C-H bond cleavage.Under the present reaction conditions 4,4'-dimethylbibenzyl and 9,10-dihydrophenanthrene were converted largely to dianions.It is suggested that all of the compounds undergoing cleavage are converted to dianions prior to cleavage.From competitive experiments the rates of reductive cleavage of most of these hydrocarbons relative to bibenzyl have been measured at -75 deg C.The relative rates of cleavage of m- and p-methylderivatives of bibenzyl may be correlated with the relative equilibrium acidities of toluene, m-xylene, and p-xylene in a modified Hammett relationship.Cleavages of benzylic C-C bonds are believed to occur by way of a preferred transition-state geometry,7, which permits the ?* orbital of the bond undergoing cleavage to interact with the HOMO's of both aromatic rings.Compounds that cannot attain this transition-state geometry are cleaved slowly if at all.The variable effect upon reaction rate of methyl groups near the bond undergoing cleavage are discussed in terms of ground-state and transition-state atrain, solvation, and polarizability of methyl groups.According to labeling experiments (o-methylbenzyl)cesium undergoes ready intramolecular sigmatropic migration of hydrogen from the methyl group to the methylene group when warmed from -75 deg C to near room temperature.
- Grovenstein, Erling,Bhatti, Amjad M.,Quest, Dean E.,Sengupta, Dibyendu,VanDerveer, Don
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p. 6290 - 6299
(2007/10/02)
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- Soft drugs: III. A new class of anticholinergic agents
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A new class of antimuscarinic drugs was designed and synthesized. The compounds are 'soft' quaternary ammonium esters in which there is only one carbon atom separating the ester oxygen and the quaternary head. The compounds are potent anticholinergics when derived from hindered 'umbrella' acids and cholinergics when derivatives of simple aliphatic acids. The more potent anticholinergics have up to 10 times higher acetylcholine antagonist activity than atropine, but they have a much shorter duration of action. The compounds cleave hydrolytically with simultaneous destruction of the quaternary head. The compounds are promising as selective, local agents, particularly as inhibitors of eccrine sweating.
- Bodor,Woods,Raper,et al.
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p. 474 - 480
(2007/10/02)
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