- Palladium(II)- and rhodium(I)-N-heterocyclic carbene complexes derived from menthol: Synthesis and characterisation
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A carbene-Pd(II) complex and a carbene-Rh(I) complex, both derived from commercially available L-(-)-menthol, have been synthesised, characterised and their X-ray single-crystal structures determined.
- Gu, Zheng-Song,Ye, Ting-Ting,Lu, Jian-Mei
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- Synthesis, characterization and hplc analysis of the (1S,2S,5R)-diastereomer and the enantiomer of the clinical candidate ar-15512
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AR-15512 (formerly known as AVX-012 and WS-12) is a TRPM8 receptor agonist currently in phase 2b clinical trials for the treatment of dry eye. This bioactive compound with menthol-like cooling activity has three stereogenic centers, and its final structure and absolute configuration, (1R,2S,5R), have been previously solved by cryo-electron microscopy. The route of synthesis of AR-15512 has also been reported, revealing that epimerization processes at the C-1 can occur at specific stages of the synthesis. In order to confirm that the desired configuration of AR-15512 does not change throughout the process and to discard the presence of the enantiomer in the final product due to possible contamination of the initial starting material, both the enantiomer of AR-15512 and the diastereomer at the C-1 were synthesized and fully characterized. In addition, the absolute configuration of the (1S,2S,5R)-diastereomer was determined by X-ray crystallographic analysis, and new HPLC methods were designed and developed for the identification of the two stereoisomers and their comparison with the clinical candidate AR-15512.
- Abás, Sònia,Escolano, Carmen,Galdeano, Carles,Pujol, Eugènia,Rodríguez-Arévalo, Sergio,Vázquez, Santiago
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- Enantiopure encaged Verkade's superbases: Synthesis, chiroptical properties, and use as chiral derivatizing agent
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Verkade's superbases, entrapped in the cavity of enantiopure hemicryptophane cages, have been synthesized with enantiomeric excess (ee) superior to 98%. Their absolute configuration has been determined by using electronic circular dichroism (ECD) spectros
- Yang, Jian,Chatelet, Bastien,Hérault, Damien,Dufaud, Véronique,Robert, Vincent,Grass, Stéphane,Lacour, Jér?me,Vanthuyne, Nicolas,Jean, Marion,Albalat, Muriel,Dutasta, Jean-Pierre,Martinez, Alexandre
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p. 139 - 146
(2019/12/27)
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- Triiodide-Mediated δ-Amination of Secondary C?H Bonds
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The Cδ?H amination of unactivated, secondary C?H bonds to form a broad range of functionalized pyrrolidines has been developed by a triiodide (I3?)-mediated strategy. By in situ 1) oxidation of sodium iodide and 2) sequestration of the transiently generated iodine (I2) as I3?, this approach precludes undesired I2-mediated decomposition which can otherwise limit synthetic utility to only weak C(sp3)?H bonds. The mechanism of this triiodide-mediated cyclization of unbiased, secondary C(sp3)?H bonds, by either thermal or photolytic initiation, is supported by NMR and UV/Vis data, as well as intercepted intermediates.
- Wappes, Ethan A.,Fosu, Stacy C.,Chopko, Trevor C.,Nagib, David A.
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supporting information
p. 9974 - 9978
(2016/08/16)
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- Synthesis and in vitro antibacterial evaluation of novel 4-substituted 1-menthyl-1,2,3-triazoles
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Menthyl 1,4-disubstituted 1,2,3-triazole derivatives of hydroxybenzaldehydes, phenols and bile acids were synthesized via click chemistry. The novel synthesized compounds were evaluated for their in vitro antibacterial activity against Enterococcus faeciu
- Khaligh, Pooneh,Salehi, Peyman,Bararjanian, Morteza,Aliahmadi, Atousa,Khavasi, Hamid Reza,Nejad-Ebrahimi, Samad
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p. 1589 - 1596
(2016/11/09)
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- Enantioselective Rhodium(I)-Catalyzed Additions of Arylboronic Acids to N-1,2,3-Triazole-Isatin Derivatives: Accessing N-(1,2,3-Triazolmethyl)-3-hydroxy-3-aryloxindoles
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Oxindoles and triazoles are very privileged frameworks in medicinal chemistry, and thus for the first time we report a catalytic asymmetric route that affords hitherto unknown families of N-(1,2,3-triazolmethyl)-3-hydroxy-3-phenyloxindoles using cheap bio
- Marques, Carolina S.,Burke, Anthony J.
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p. 3518 - 3526
(2016/11/29)
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- Diastereoselective desymmetrization of diarylphosphinous acid-borane amides under Birch reduction
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Treatment of diarylphosphinous acid-borane amides possessing chiral amido functionality with an alkali metal solution in liquid ammonia induced a preferential dearomatization of one aryl substituent at phosphorus leading to the formation of non-equimolar amounts of diastereomers. Diastereoselectivity of dearomatization depends strongly on the structure of a chiral auxiliary.
- Stankevi?, Marek
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p. 6082 - 6102
(2015/06/08)
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- Synthesis and structures of (-) menthyl and (+) neomenthyl substituted enantio pure bis(1,2,3-triazol-5-ylidene)PdI2 complexes and PEPPSI type (1,2,3-triazol-5-ylidene) (pyridine)PdI2complexes. Comparison of catalytic activities for C-C coupling
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(-) Menthol was converted to 1-menthyl-3-methyl-4-phenyltriazolium iodide and 1-neomethyl-3-methyl-4-phenyltriazolium iodide in four steps. These triazolium salts that are enantio pure but diastereo isomers, served as precursors for the synthesis of the corresponding enantio pure bis(1,2,3-triazol-5-ylidene)PdI2 complexes with menthyl and neomenthyl wing tip groups. The palladium complexes were synthesized in high yields using a recently developed mild method under base free and silver free conditions at ambient temperature. These triazolium salts also served as precursors for the synthesis of the corresponding enantio pure PEPPSI type (1,2,3-triazol-5-ylidene) (pyridine)PdI2 complexes. All the complexes were thoroughly characterized by spectroscopic and single crystal XRD data. The relative catalytic activities of these complexes were compared for Suzuki-Miyaura C-C coupling.
- Mohan, Arumugam,Ramkumar, Venkatachalam,Sankararaman, Sethuraman
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supporting information
p. 115 - 121
(2015/10/12)
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- Iron(III)-catalyzed halogenations by substitution of sulfonate esters
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A novel halogenation reaction from sulfonates catalyzed by iron(III) is described. The reaction can be performed as a stoichiometric or a catalytic version. This reaction provides a convenient strategy for the efficient access to structurally diverse secondary chlorides, bromides and iodides. The stereochemical course of the reaction is governed by the substrate and the experimental conditions. Secondary alcohols modified as quisylates or pysylates are substantially more reactive. Aliphatic quisylates proceed with overall inversion of configuration under catalytic conditions. Chemoselectivity in bismesylates was observed in favour of the secondary mesylate. Additionally, based on the experimental results, a possible catalytic cycle for the halogenation has been proposed.
- Ortega, Nuria,Feher-Voelger, Andres,Brovetto, Margarita,Padron, Juan I.,Martin, Victor S.,Martin, Tomas
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supporting information; experimental part
p. 963 - 972
(2011/06/20)
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- Inversion of secondary chiral alcohols in toluene with the tunable complex of R3N{single bond}R′COOH
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The SN2 reaction of enantiomerically pure sulfonates with the tunable complex of R3N-R′COOH in toluene has been extensively studied. It was revealed that the molar ratio of the tertiary amines and carboxylic acids in the complex of R3NR′COOH is crucial for the SN2 reaction, and should be tuned for each sulfonate to give the best yield. Fifteen sulfonates 1 and 3-13 (Scheme 2) were prepared and transformed into 22 corresponding inverted esters 2 and 14-24 (Scheme 2) in good to high yields.
- Shi, Xiao-Xin,Shen, Chun-Li,Yao, Jian-Zhong,Nie, Liang-Deng,Quan, Na
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experimental part
p. 277 - 284
(2010/05/18)
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- General, robust, and stereocomplementary preparation of β-ketoester enol tosylates as cross-coupling partners utilizing TsCl-N-methylimidazole agents
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(Chemical Equation Presented) We have developed a general, robust, and cost-effective method for the (E)- or (Z)-stereocomplementary enol tosylation of β-ketoesters using TsCl-N-methylimidazole (NMI)-Et3N or LiOH. TsCl coupled with NMI formed a
- Nakatsuji, Hidefumi,Ueno, Kanako,Misaki, Tomonori,Tanabe, Yoo
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supporting information; experimental part
p. 2131 - 2134
(2009/05/26)
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- Reduction of alkyl and vinyl sulfonates using the CuCl2· 2H2O-Li-DTBB(cat.) system
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The reduction of a series of alkyl mesylates, dimesylates and triflates to the corresponding hydrocarbons was efficiently performed using a reducing system composed of CuCl2·2H2O, an excess of lithium sand and a catalytic amount (5 mol%) of 4,4′-di-tert-butylbiphenyl (DTBB), in tetrahydrofuran at room temperature. The process was also applied to enol and dienol triflates affording alkenes and dienes, respectively. The use of the deuterated copper salt CuCl2·2D2O allowed the simple preparation of the corresponding deuterated products.
- Radivoy, Gabriel,Alonso, Francisco,Moglie, Yanina,Vitale, Cristian,Yus, Miguel
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p. 3859 - 3864
(2007/10/03)
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- Chloromethanesulfonate as an efficient leaving group: Rearrangement of the carbon-carbon bond and conversion of alcohols into azides and nitriles
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The chloromethanesulfonate (monochlate) served as an efficient leaving group for rearrangement of the carbon-carbon bond and conversion of alcohols into azides and nitriles. The treatment of the monochlate 16a with zinc acetate in dioxane at 90 °C effected migration of the 4α-methyl group to give alkene 17a. Upon similar treatment of the monochlates 22a, 25a, 28a, and 31a with zinc acetate, the carbon-carbon bonds antiperiplanar to the hydroxyl groups efficiently migrated to afford the alkenes 23a, 26a-c, 29a,b, and 32a, respectively. In the case of the diol 40, the monochlate was converted into the ketone 41 via a rearrangement-ring expansion. The reaction of the monochlates 44a, 47a, 49a, 52a, and 57a with sodium azide or lithium azide in N,N-dimethylformamide efficiently afforded the azides with inversion of the configuration. The introduction of a nitrile group to the sterically hindered alcohol 59 was performed in high yield by the reaction of the monochlate 60a with sodium cyanide.
- Shimizu, Takeshi,Ohzeki, Tomoya,Hiramoto, Katsuya,Hori, Nobuyuki,Nakata, Tadashi
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p. 1373 - 1385
(2007/10/03)
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- Reduction of sulfonates and aromatic compounds with the NiCl2 · 2H2O- Li-arene (cat.) combination
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A series of alkyl mesylates, dimesylates and alkyl or aryl triflates have been reduced to the corresponding hydrocarbons with nickel(II) chloride dihydrate, an excess of lithium powder and a catalytic amount of DTBB (10 mol%) in THF at room temperature. This methodology applied to enol triflates allowed the preparation of olefins or alkanes depending on the amount of the Ni(II) salt used. The reduction of different aromatic or heteroaromatic compounds under the above mentioned conditions leads to the partial or total reduction of the starting materials, the process being a reasonable alternative to the well-known Birch reaction. The use of the deuterium oxide- containing nickel(lI) salt allows the simple preparation of deuterated products.
- Radivoy, Gabriel,Alonso, Francisco,Yus, Miguel
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p. 14479 - 14490
(2007/10/03)
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- Synthesis of cycloalkyldiarylphosophines
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Phosphines having two aryl groups and one alkyl-substituted cycloalkyl group bonded to a phosphorus atom are formed by reacting an alkali metal diarylphosphide with a monoalkyl- or polyalkyl-substituted cycloalkyl mesylate or tosylate in which an alkyl gr
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- Efficient method for inversion of secondary alcohols by reaction of chloromethanesulfonates with cesium acetate
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Inversion of a variety of secondary alcohols using the (chloromethylsulfonyl)oxy group as a favorable leaving group with cesium acetate in the presence of 18-crown-6 has been performed to give the inverted acetates in high yields.
- Shimizu, Takeshi,Hiranuma, Sayoko,Nakata, Tadashi
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p. 6145 - 6148
(2007/10/03)
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- An Assessment of the Causes of the "Cesium Effect"
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Cesium alkanoates (chiefly the propionate) have been investigated for their solubility, nucleophilic, reactivity and degree of ion pairing in dimethylformamide (DMF) and, in some cases, dimethyl sulfoxide (DMSO) solutions. 133Cs NMR has been used to establish the degree of ion pairing.From the data obtained it is concluded that the cesium ion is virtually completely solvated and that the carboxylates are essentially free and highly reactive.The consequences of this effect on macrocyclization by means of nucleophilic substitution are discussed.
- Dijkstra, Gerard,Kruizinga, Wim H.,Kellogg, Richard M.
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p. 4230 - 4234
(2007/10/02)
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- Stereochemistry of Nucleophilic Substitution of Menthyl Derivatives with Anion of Diphenylphosphine Oxide by an Action of Sodium Dihydridobis(2-methoxyethanolato)aluminate
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The reaction of an anion of diphenylphosphine oxide prepared by the action of sodium dihydridobis(2-methoxyethanolato)aluminate on the oxide with various menthyl or neomenthyl halides and sulfonates were studied to clarify the sterochemistry of the substi
- Yamashita, Mitsuji,Soeda, Yukio,Suzuki, Nobuyoshi,Yamada, Manabu,Tsunekawa, Kenji,et al.
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p. 1871 - 1872
(2007/10/02)
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- Cob(I)alamin als Katalysator. Retention der Konfiguration bei der reduktiv-protonenuebertragenden Spaltung der Co,C-Bindung eines Alkylcobalamins
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Using catalytic amounts of cob(I)alamin (see Scheme 1) in aqueous acetic acid (-)-α-pinen (1) and (-)-β-pinen (2; s.Scheme 3) have been reduced.A large excess of metallic zinc served as electron source.The saturated products 5-8 (see Scheme 3) and the mechanistic aspects of their generation are discussed.The relative amounts of cis- (5) and trans-pinane (6) lead to the conclusion that the reductive cleavage of the Co, C-bond accompained by H+ transfer in an alkylcobalamin occurs with retention of configuration.This result is in agreement with the corresponding cleavage of the Co,C-bond of an alkylcobalt complex .
- Fischli, Albert,Mueller, Peter Michael
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p. 1619 - 1627
(2007/10/02)
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