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Efficient Chemoenzymatic Synthesis, Cytotoxic Evaluation, and SAR of Epoxysterols
Carvalho, João F. S.; Silva, M. Manuel Cruz; Moreira, João N.; Simões, Sérgio; Melo, M. Luísa Sá eA library of diastereomerically pure epoxysterols, prepared by combining chemical and enzymatic methodologies, was evaluated for cytotoxicity toward human cancer and noncancer cell lines. Unsaturated steroids were oxidized by magnesium bis(monoperoxyphthalate) hexahydrate in acetonitrile, and the resulting epimeric epoxides were enzymatically separated using Novozym 435 or lipase AY. Some of the synthesized epo...
Regioselective enzymatic acylation of vicinal diols of steroids
Silva, M. Manuel Cruz; Riva, Sergio; Melo, M. Luísa Sá eMonoacylated derivatives of a complete set of 2,3- and 3,4-vicinal diols of steroids were prepared by regioselective lipase-catalysed transesterification reactions. The enzymes displayed different selectivities towards the vicinal diols depending on the configuration of the hydroxyl groups. ; http://www.sciencedirect.com/science/article/B6THR-4FGX84H-2/1/c23744db4c590d02acf7c82018be5720
Highly selective lipase-mediated discrimination of diastereomeric 5,6-epoxyster...
Silva, M. Manuel Cruz; Riva, Sergio; Melo, M. Luísa Sá eStereoisomerically pure 3[beta]-hydroxy-5,6-epoxysteroids were obtained by combining selective chemical methods for [alpha]- and [beta]-epoxidation of [Delta]5-unsaturated steroids with enzymatic stereoselective esterification of the 3[beta]-hydroxyl group. 5[beta],6[beta]-Epoxy-3[beta]-hydroxysteroids were efficiently acylated by Novozym 435 and lipase AK, whereas 5[alpha],6[alpha]-epoxy-3[beta]-hydroxysteroid...
The biocatalyzed stereoselective preparation of polycyclic cyanohydrins
Silva, M. Manuel Cruz; Melo, M. Luísa Sá e; Parolin, Marco; Tessaro, Davide; Riva, Sergio; Danieli, BrunoThe enzyme-mediated preparation of enantiomerically or diastereomerically enriched polycyclic cyanohydrins has been investigated. Oxynitrilase-catalyzed cyanurations gave excellent results with the bicyclic aldehydes tested. On the other hand, enantio- or diastereoselective acylation, catalyzed by lipase PS or subtilisin, proved to be a more versatile methodology, giving good results even with sterically hinder...
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