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The asymmetric heterogeneous catalytic cascade reaction of ethyl 2-nitro-3-methylphenylpyruvate has been investigated over platinum modified by cinchonidine in continuous-flow system using a fixed-bed reactor. The high selectivities and enantioselectivities of the (R)-3-hydroxy-3,4-dihydro-8-methylquinolin-2(1H)-one obtained in previous studies in batch reactor were not reached. The catalyst was in situ prehydrogenated and premodified with cinchonidine, and the reaction conditions optimized for batch reactor were changed in order to increase the yield and enantioselectivity of the desired product under flow conditions. Results obtained in the flow apparatus contributed to the understanding of the reaction pathway through which the quinolone is formed. It was shown that, at low conversions, the intermediate aminohydroxyester desorbs preferentially and is further transformed by readsorption and cyclization to the quinolone derivative after complete disappearance of the 2-nitrophenylpyruvate. However, at high conversion, the formation of the quinolone may also occur instantaneously on the Pt surface following the two competitive reduction steps. The ratio of the product formed through these two pathways is determined by the reaction conditions and the system used.

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Journal of Flow Chemistry
Authors: Rajesh Munirathinam, Andrea Leoncini, Jurriaan Huskens, Herbert Wormeester, and Willem Verboom

Cinchona alkaloid and proline derivatives as enantioselective catalysts were covalently attached onto the inner walls of a microreactor using glycidyl methacrylate polymer brushes. The successful formation of the organocatalyst-functionalized brush layers on flat silicon oxide surfaces was confirmed by several techniques such as Fourier transform infrared (FT-IR), ellipsometry, and X-ray photoelectron spectroscopy (XPS). The applicability of the cinchona alkaloid (cinchonidine or quinidine)- and proline-containing polymer brushes in a microreactor was demonstrated for the Diels–Alder reaction between anthrone and N-substituted maleimides, and the aldol reaction between 4-nitrobenzaldehyde and cyclohexanone, respectively, which showed moderate conversions (up to 55% and 23%, respectively) and moderate to good enantioselectivities (up to 55% and 93%, respectively). The pristine catalytic activity of the microreactor was intact even after 1 month.

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Abstract  

By means of hydrosilylation reactions between functional olefins and triethoxysilane in the presence of Speier's catalyst and sol-gel transformations of the reaction products, a number of optically active and complexing alkenes (quinine, quinidine, cinchonine, cinchonidine, alprenolol, N-allylrhodanine and hemin) were immobilized on the surface of silica. The structures of the compounds formed and the nature of their bonding with the surface were studied by DRIFT and NMR spectroscopies. The concentrations of olefins anchored to the surface layer of the silica matrix were estimated by UV spectroscopy.

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cinchonidine (CD) and ( S , S )-pantoyl-naphthylethylamine [ 5 ] or ( R , R )-pantoyl-naphthylethylamine and cinchonine (CN) were applied [ 11 ]. A similar behavior was observed for the mixture of CD and O-phenylcinchonidine (PhOCD) [ 6 ]. Although

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-alumina and on Pt-alumina-cinchonidine catalysts ” G. Szo˝llo˝si , Z. Makra , F. Fülöp , M. Bartók Catalysis Letters 2011 , 141 , 1616 – 1620 . “ Intramolecular cyclisation of isosorbide by dimethylcarbonate chemistry ” P

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solution for injection (Toradol®, Syntex, Sydney, Australia) followed by separation and isolation of the individual ( R ) - and ( S )-enantiomers by the fractional crystallization of the diastereomeric cinchonidine salt as reported by Gusman et al., [ 66

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