- CuII/TEMPO-Catalyzed Enantioselective C(sp3)–H Alkynylation of Tertiary Cyclic Amines through Shono-Type Oxidation
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A novel strategy for asymmetric Shono-type oxidative cross-coupling has been developed by merging copper catalysis and electrochemistry, affording C1-alkynylated tetrahydroisoquinolines with good to excellent enantioselectivity. The use of TEMPO as a co-catalytic redox mediator is crucial not only for oxidizing a tetrahydroisoquinoline to an iminium ion species but also for decreasing the oxidation potential of the reaction. A novel bisoxazoline ligand is also reported.
- Chen, Zhi-Hao,Gao, Pei-Sen,Mei, Tian-Sheng,Sun, Bing,Wang, Zhen-Hua,Weng, Xin-Jun,You, Shu-Li,Zheng, Chao
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- Intramolecular Imidazole-Promoted General-Base Catalysis of the Hydrolysis of an Acetylimidazole
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Intramolecular general-base catalysis of the hydrolysis of an acetylimidazole by imidazole is assessed by studying the hydrolysis of 2-(imidazol-2-ylmethyl)-N-acetylimidazole (3).The pH vs. log kobsd profile exhibits three major domains that consist of H2O attack on the protonated acetylimidazolium unit,OH- attack on the neutral material, and an intramolecular general-base catalysis of H2O on the neutral species.Consistent with the latter is a plateau observed in the pH profile (k3 = 1.02*10-3 s-1) at neutrality and a solvent kinetic isotope effect of kH2O/kD2O = 2.8 in that region.The effective molarity of the intramolecular imidazole in 3 can be assessed by comparing the value of k3 with the second-order rate constant for 2-methylimidazole catalyzing the hydrolysis of 2-methyl-N-acetylimidazole (4).After the difference in the imidazole pKa values is corrected for, the effective molarity of the intramolecular catalyst is 3 M.
- Brown, R.S.,Clewley, R.G
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- Synthesis of C2-symmetric bisamidines: A new type of chiral metal-free lewis acid analogue interacting with carbonyl groups
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(Chemical Equation Presented) The chiral bisamidine 5 has been prepared in just two steps from malonodinitrile. In the monocationic form this compound adopts a planar conformation with an almost convergent orientation of two N-H groups. Ketones, aldehydes
- Akalay, Deniz,Duerner, Gerd,Bats, Jan W.,Bolte, Michael,Goebel, Michael W.
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- Analogs of biologically active compounds IX.1 Synthesis of several new uracil and pteridine 6-azaanalogs based on cyclization of arylhydrazones derived from mesoxalic acid
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A series of 5C and 5N substituted 3-oxo-2-phenyl-1,2,4-triazine-6-carbonitriles and 8-imino-2-arylpyrimido[4,5-e][1,2,4]triazine-3,6(2H,5H)-diones (6-aryl-6-azapteridines) are described via a cyclocondensation reaction from the corresponding aryliminohydrazones with CDI. The required aryliminohydrazones were obtained from the starting compound – malononitrile. These prepared compounds were tested for cytotoxic activity on cancer cell lines.
- Novosád, David,Styskala, Jakub
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- PROCESS FOR SYNTHESIS OF PICOLINAMIDES
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The present technology relates to processes, mixtures and intermediates useful for making picolinamide fungicides. The picolinamide compounds are prepared by processes that include coupling together a 4-methoxy-3-acyloxypicolinic acid with key 2-amino-L-alaninate esters derived from substituted 2-phenylethanols.
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Paragraph 0248
(2021/04/23)
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- Copper-Nitrene-Catalyzed Desymmetric Oxaziridination/1,2-Alkyl Rearrangement of 1,3-Diketones toward Bicyclic Lactams
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Although copper-nitrene has been extensively studied as a versatile active species in various transformations, asymmetric reactions involving copper-nitrene have been limited to the aziridination of olefins. Herein, we report the novel copper-nitrene-catalyzed desymmetric oxaziridination reaction of cyclic diketones with alkyl azides and the subsequent rearrangement of the resulting highly active intermediate, which produces a synthetically challenging chiral bicyclic lactam containing a quaternary carbon center. This procedure not only enriches the copper-nitrene-catalyzed asymmetric reactions, but also provides an alternative strategy to address the inherent challenges of catalytic asymmetric Schmidt reactions. This unique reaction could inspire the investigation of novel copper-nitrene-catalyzed asymmetric transformations and their reaction mechanisms.
- Han, Xue,Shan, Li-Xin,Zhu, Jin-Xin,Zhang, Chang-Sheng,Zhang, Xiao-Ming,Zhang, Fu-Min,Wang, Hong,Tu, Yong-Qiang,Yang, Ming,Zhang, Wen-Shuo
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supporting information
p. 22688 - 22692
(2021/09/18)
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- Enantioselective Synthesis of N-Benzylic Heterocycles: A Nickel and Photoredox Dual Catalysis Approach
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Reported herein is a dual nickel- and photoredox-catalyzed modular approach for the preparation of enantioenriched N-benzylic heterocycles. α-Heterocyclic carboxylic acids, easily obtainable from common commercial material, are reported as suitable substrates for a decarboxylative strategy in conjunction with a chiral pyridine-oxazoline (PyOx) ligand, providing quick access to enantioenriched drug-like products. The presence of a directing group on the heterocyclic moiety is shown to be beneficial, affording improved stereoselectivity in a number of cases.
- Pezzetta, Cristofer,Bonifazi, Davide,Davidson, Robert W. M.
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supporting information
p. 8957 - 8961
(2019/11/11)
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- Modular ligand variation in calcium bisimidazoline complexes: Effects on ligand redistribution and hydroamination catalysis
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A series of calcium complexes supported by chiral bisimidazoline ligands have been studied in the catalytic intramolecular hydroamination/cyclisation of amino-olefins. The complexes [Ca(R-BIM){N(SiMe3)2}(THF)] (R = 4-C6Hs
- Wixey, James S.,Ward, Benjamin D.
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supporting information; experimental part
p. 7693 - 7696
(2011/09/20)
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- Spectroscopic studies on complexes of magnesium (II) with C2-chiral bis-oxazolines
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The configurations of chloro, ethyl and bis-complexes of magnesium with C2-chiral bis-oxazolines such as 2,2′-methylenebis[(4S)-4-iso-propyl-2-oxazoline] (MBIO). 2,2′-methylenebis[(4S)-4-tert-butyl-2-oxazoline] (MBTO) and 2,2′-methylenebis[(4S)-4-phenyl-2-oxazoline] (MBPO) have been investigated on the basis of spectroscopic studies. The IR and NMR (1H, 13C) data suggested that the bis-oxazoline ligands coordinated magnesium (II) through both the nitrogen atoms. The molecular weight determination in nitrobenzene indicated the dimeric nature of chloro and ethylmagnesium complexes whereas bis-magnesium complexes were found to be monomeric.
- Singh
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p. 1713 - 1717
(2007/10/03)
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- Thiono and Dithio Esters, 40. - Reactions of Dithionomalonic Esters with Nucleophilic Nitrogen Bases
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Dithionomalonic esters 1, obtained from malonitrile via malonodiimidium salts 5 by thiolysis, react with amines under elimination of H2S to form the 3-amino-thioacrylic O-esters 11.The alkali salts of 1 condense with amines to give the malonodithioamides 12 by loss of 2 molecules of alcohol.Oxidative cyclization of 11 leads to the isothiazoles 16-18.Reaction of 1 with hydrazines gives rise to the pyrazoles 20-22; with amidines the pyrimidines 23 and 24 were obtained.
- Hartke, Klaus,Mueller, Heinz-Georg
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p. 863 - 871
(2007/10/02)
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