- A bifunctional metal–organic framework platform for catalytic applications
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DUT-71 (DUT – Dresden University of Technology), a copper paddle wheel based framework, was used as a platform for postsynthetic modification to introduce specific catalytically active sites and to enhance the catalytic activity for fine chemicals product
- Müller, Philipp,Bon, Volodymyr,Senkovska, Irena,Nguyen, Khoa D.,Kaskel, Stefan
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supporting information
p. 382 - 386
(2019/01/03)
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- 3-Aminoquinazoline–phosphine ligands and their ruthenium(II) complexes: application in catalytic hydrogenation and transfer hydrogenation reactions
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3-Aminoquinazolinone–phosphine proligands (5a–e) and their Ru(II) complexes (6a–e) were prepared and characterized by NMR (1H, 13C, 31P{1H}), FTIR and microanalysis. The 3-aminoquinazolinone–phosphine ligands were found to coordinate with the Ru(II) center via their phosphorus and nitrogen atoms. The Ru(II) complexes were applied as catalysts for the hydrogenation and transfer hydrogenation of prochiral ketones. The results showed that these complexes are efficient transfer hydrogenation catalysts.
- Y?lmaz, Mustafa Kemal,Kele?, Mustafa
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p. 285 - 292
(2018/02/19)
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- The Synthesis of Chiral α-Aryl α-Hydroxy Carboxylic Acids via RuPHOX-Ru Catalyzed Asymmetric Hydrogenation
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A ruthenocenyl phosphino-oxazoline-ruthenium complex (RuPHOX?Ru) catalyzed asymmetric hydrogenation of α-aryl keto acids has been successfully developed, affording the corresponding chiral α-aryl α-hydroxy carboxylic acids in high yields and with up to 97% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 5000 S/C) and the resulting products can be transformed to several chiral building blocks, biologically active compounds and chiral drugs. (Figure presented.).
- Guo, Huan,Li, Jing,Liu, Delong,Zhang, Wanbin
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p. 3665 - 3673
(2017/09/11)
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- Penipyridones A-F, Pyridone Alkaloids from Penicillium funiculosum
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Six new pyridone alkaloids, named penipyridones A-F (1-6), were isolated from the fermentation broth of an Antarctic moss-derived fungus, Penicillium funiculosum GWT2-24. Their structures were elucidated from extensive NMR and MS data. Although they possess the same major chromophore and some of them presented almost mirror ECD spectra, their absolute configurations were found to be uniformly S, as evidenced by X-ray single-crystal diffraction analysis, stereocontrolled total synthesis, and chemical conversions. TDDFT-ECD calculations of compounds 3 and 6 revealed that subtle conformational changes are responsible for the significantly different ECD curves. None of the compounds were cytotoxic (IC50 > 50 μM), while compounds 1, 2, 5, and 7 elicited lipid-lowering activity in HepG2 hepatocytes.
- Zhou, Haibo,Li, Liyuan,Wu, Chongming,Kurtán, Tibor,Mándi, Attila,Liu, Yankai,Gu, Qianqun,Zhu, Tianjiao,Guo, Peng,Li, Dehai
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p. 1783 - 1790
(2016/08/02)
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- 3-Aminoquinazolinones as chiral ligands in catalytic enantioselective diethylzinc and phenylacetylene addition to aldehydes
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A series of readily known enantiomerically pure 3-aminoquinazolinones 1a-d were synthesised from easily accessible chiral pool α-hydroxy acids and α-amino acids in only four steps without any requirement of chromatography. These quinazolinones were examined as chiral ligands for catalytic enantioselective diethylzinc and phenylacetylene additions to aldehydes. For enantioselective alkylations, the effects of temperature, solvent, diethylzinc and ligand criteria were analysed, and the desired chiral alcohols were obtained in up to 86% ee. 3-Aminoquinazolinones 1a-d were also shown to be very useful ligands in enantioselective alkynylations of aldehydes. Based upon the optimised conditions, the corresponding propargylic alcohols were obtained in up to 94% ee.
- Karabuga, Semistan,Karakaya, Idris,Ulukanli, Sabri
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p. 851 - 855
(2014/06/23)
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- Mandelic acid derived α-aziridinyl alcohols as highly efficient ligands for asymmetric additions of zinc organyls to aldehydes
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A straightforward synthesis of a series of new catalysts containing secondary hydroxyl and aziridine moieties as nucleophilic centers built on the chiral scaffold of (S)-(+)-mandelic acid is described. The new compounds have been tested for the enantioselective addition of diethylzinc and phenylethynylzinc to aryl and alkyl aldehydes, which yielded the corresponding chiral alcohols in high chemical yields (up to 95%) and with excellent ee's of ca. 90%. The strong influence of the stereogenic center located at the aziridine subunit on the stereochemical outcome is also reported on.
- Rachwalski, Michal,Jarzynski, Szymon,Jasinski, Marcin,Lesniak, Stanislaw
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p. 689 - 693
(2013/07/11)
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- New chiral ligands derived from mandelic acid: Synthesis and application in the asymmetric phenyl transfer reaction to an aromatic aldehyde
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Starting from inexpensive enantiopure (R)- and (S)-mandelic acid, a range of α-hydroxy-2-oxazolines has been prepared. The synthesis involves the condensation of the acid chloride with a vicinal amino alcohol, followed by intramolecular cyclization to form the oxazoline ring. The resulting compounds have been used as ligands in the asymmetric phenyl transfer reaction to 4-chlorobenzaldehyde, employing a mixture of triphenylborane and diethylzinc as the phenyl source. Good yields (up to 76%) and moderate enantioselectivities (up to 35%) have been achieved.
- Bolm, Carsten,Zani, Lorenzo,Rudolph, Jens,Schiffers, Ingo
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p. 2173 - 2180
(2007/10/03)
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- Highly stereoselective Friedel-Crafts type cyclization. Facile access to enantiopure 1,4-dihydro-4-phenyl isoquinolinones
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The present report describes a stereoselective synthesis of 1,4-dihydro-4-phenyl isoquinolinones 5 based on a stereoselective Friedel-Crafts type cyclization. Cyclization precursors 1 were prepared in two steps, from the readily available (S)-mandelic acid, in 60-80% overall yield. The stereoselective electrophilic cyclization was accomplished in 20-86% yield and with 20-97% ee. In the course of this work, the presence of the amide carbonyl was found to be particularly important to guarantee a stereospecific process during the electrophilic aromatic substitution.
- Philippe, Nicolas,Denivet, Fran?ois,Vasse, Jean-Luc,Sopkova-De Olivera Santos, Jana,Levacher, Vincent,Dupas, Georges
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p. 8049 - 8056
(2007/10/03)
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- AUXILIARY SRTUCTURE AND ASYMMETRIC INDUCTION IN THE "MUKAIYAMA-ALDOL" REACTIONS OF CHIRAL SILYL KETENE ACETALS
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A variety of chiral auxiliaries R*OH were prepared and tested for levels of asymmetric induction control in the "Mukaiyama-aldol" reaction of chiral silyl ketene acetals.Structural features required for high levels of control are discussed.
- Gennari, Cesare,Molinari, Francesco,Cozzi, PierGiorgio,Oliva, Ambrogio
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p. 5163 - 5166
(2007/10/02)
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- STEREOCHIMIE DE LA REDUCTION ELECTROCHIMIQUE D'α-CETOAMIDES OPTIQUEMENT ACTIVES I. ELECTROREDUCTION DE LA S(-) N-(α-METHYLBENZYL)BENZOYLFORMAMIDE
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Electrochemical reduction of the title compound has been investigated in hydro-alcoholic medium, at a mercury cathode.Polarographic study shows adsorption of the substrate in very acidic medium (pH 5.5.Controlled potential electrolyses give the corresponding mandelamide in a quasi-quantitative yield; titration of the mixture of the two epimers is achieved by proton NMR at 300 MHz.In very acidic medium, preferential formation of the RS mandelamide is observed (higher optical yield:12.5percent).On the contrary, SS mandelamide is generally the main stereoisomerin acetic or ammoniacal buffer; however, when electroreductions are carried out at very cathodic potentials, again preferential formation of the RS epimer is observed.Stereochemistry of the reduction is explained taking into account conformations of the starting molecule and protonation of the carbanion resulting from a 2 electron reduction.
- Boulmedais, Ali,Jubault, Michel,Tallec, Andre
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p. 610 - 617
(2007/10/02)
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- The Preparation and Absolute Configuration of the Optically Active Forms of the Diastereoisomers of 2-(1-Phenylethyl)amino-1-phenylethanol and Their Use as Chiral Auxiliaries in the Asymmetric Reduction of Acetophenone with Modified Lithium Aluminium Hydrides
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(1S,2S)-(-)-2-(1-Phenylethyl)amino-1-phenylethanol (4b) (α-form) and the (1S,2R)-(+)-diastereoisomer (4f) (β-form) were prepared by lithium aluminium hydride reduction of the optically active amides derived from the appropriate mandelic acids and 1-phenylethylamines.The preparative methods give the absolute stereochemistry.The aminoethanols (4) were used along with the lower alcohols to prepare chirally modified lithium aluminium hydrides which were in turn used to reduce acetophenone.The optical yields varied, giving at best, under low temperature conditions and use of a 25 percent optical yield.
- Garry, Scott W.,Neilson, Douglas G.
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p. 601 - 606
(2007/10/02)
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