Introductory will be considered all basic stereochemical terms and concepts, as e.g. elements of conformational analysis and dynamic stereochemistry, indispensable for understanding stereoselective transformations in organic chemistry. Stereochemical terms (chirality, stereogenic center, prochirality, enantiotopy and diastereotopy of faces and ligands) will be explained and exemplified. Symmetry elements present in achiral, prochiral and chiral molecules will be indicated. The importance of kinetic control (diastereoselective transition states) of enantioselective and diastereoselective reactions vs. thermodynamic control will be emphesized.
Diastereoselective reactions will be discussed on the classic examples of synthesis of enantiomerically enriched amino acids (Northrop, Vigneron), and on the Weinges synthesis of Me-DOPA. Mayers and Enders approach to the C-C bond-forming reactions using chiral auxiliaries (4,5-disubstituted 1,3-oxazolines; SAMP and RAMP) derived from the available building blocks will be elaborated. An example of chiral Mannich reaction based on L-proline-derived Mannich base will be given.
Progress in the field of total syntheses of natural product, which usually consist of consecutive set of diastereoselective transformations starting from the , will be demonstrated by the classic Confalone synthesis of (+)-biotine, and recent process to the same product scaled-up by Novartis.
Enantioselective catalytic reactions, formerly known as asymmetric syntheses, are devided according to the nature of the catalyst to organometallic, organocatalytic, and biocatalytic, i.e. enzyme catalyzed transformations. They represent unique set of synthetic methodologies to enantiomerically pure compounds (EPC). From a broad range of reactions catalyzed by the chiral organometallic complexes (D.1.) are selected hydrogenation of the C=C bond, cyclopropanation of C=C bond, and allylic alkylation.
An overview of asymmetric organocatalysis will be supported by some recent examples. Some results of inspiring work of K.A. Jorgensen in this field (enantioselective Friedel-Crafts reaction, enantioselective Diels-Alder reaction with inverse electron demand) will be discussed as a separate chapter of oganocatalysis.
Consideration of biocatalytic processes will include enzyme catalyzed kinetic and dinamic kinetic resolution, both catalyzed by lipases.
Specific case of desymmetrization of meso-compounds will be exemplified by transformations cyclic anhydrides completed by chiral chemical auxiliaries.
Separate chapter is devoted to analytical and preparative
chromatography>. Separation of enantiomers on the selected, brush-type
chiral stationary phases (CSPs) and chromatographic control of optical purity will be discussed. Simulated moving bed (SMB) technology in the large-scale enantioseparation will be explained, and its advantages in development of chiral drugs underlined.
Concluding chapter is devoted to the impact of stereoselective, in particular enantioselective, syntheses and chromatographic enantioseparation on development of new, enantiopure drug entities.
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- OBVEZNA LITERATURA:
Vitomir Šunjić, Michael J. Parnham: Signposts to Chiral Drugs, Organic Synthesis in Action 1st Edition., Springer Basel, 2011.
Vittorio Caprio, Jonathan M.J.Williams: Catalysis in asymmetric synthesis. - 2nd ed. A John Wiley and Sons, Ltd. 2008.
Albrecht Berkessel, Harald Groeger: Asymmetric Organocatalysis -From Biomimetic Concepts to Applications in Asymmetric Synthesis, WILEY-VCH Verlag GmbH & Co.KGaA, Weinheim, 2005.
znanstveni i revijalni članci, znanstvene monografije
- DODATNA LITERATURA:
znanstveni i revijalni članci, znanstvene monografije
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