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Bratislava, Slovakia

Sebesta R.,Comenius University | Latika A.,Synkola
Central European Journal of Chemistry

Enantioselective organocatalytic Michael additions affords useful building blocks for many biologically and medicinally relevant compounds. Ionically-tagged diphenylprolinol silyl ether efficiently catalyzes several Michael additions of aldehydes to nitroalkenes in ionic liquids. The Michael additions work well in ionic liquids; yields up to 95% and enantioselectivities up to 95% ee were achieved. Furthermore, in some cases, the catalytic system was reusable. © Versita Sp. z o.o. Source

Organocatalytic Michael addition of alkoxyacetaldehyde 1 to N-protected 2-nitroethene-1-amine 2 (Scheme2) is a key step in the synthesis of an important antiviral agent, oseltamivir. Screening of a large array of structurally diverse acids as potential promoters led to the identification of several useful acidic additives for this reaction (Tables1-4). Also other reaction parameters were investigated with the aim of improving the diastereoselectivity of the Michael addition, while maintaining high enantiomer purity and yield (Tables5 and 6). Copyright © 2012 Verlag Helvetica Chimica Acta AG, Zürich, Switzerland. Source

Santa Maria D.,University of Bio Bio | Claramunt R.M.,University of Bio Bio | Bobosik V.,Synkola | Torralba M.C.,Complutense University of Madrid | And 3 more authors.

A total number of nineteen 2-arylbenzotriazoles related to the UV absorber Tinuvin P have been studied. Moreover, besides those bearing a 2′-hydroxy substituent, known to experience ESIPT (Excited-State Intramolecular Proton Transfer), we have also prepared three compounds having another ortho-hydroxy group at position 6′. The X-ray molecular structures of five key representatives have been determined and some important features related to their behavior discussed on the basis of solution and solid-state NMR, as well as B3LYP/6-311++G(d,p) computational results. © 2013 Elsevier Ltd. All rights reserved. Source

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