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Design, Synthesis, and Application of Novel Bifunctional (Thio)urea Organocatalysts Derived from Saccharides & Catalytic Asymmetric C−H Arylation of (η6-Arene)Chromium Complexes
Gergelitsová, Ivana ; Veselý, Jan (advisor) ; Sedlák, Miloš (referee) ; Urban, Milan (referee)
The first part of the thesis is focused on the design, synthesis, evaluation, and application of novel bifunctional (thio)urea organocatalysts derived from saccharides. Combination of H-bonding donor (thio)urea moiety with Lewis base active site in a single chiral scaffold (e.g., 1,2-trans-cyclohexyl, cinchona alkaloids, 1,1'-binaphthyl) is a popular motif in catalyst design. Only limited attention has been paid to the synthesis of bifunctional (thio)ureas using saccharides as a chiral scaffold. Saccharides bring the advantage of the availability of various diastereomeric forms. Moreover, they offer modification of steric, electronic, and solubility properties via O-substitution. Three types of novel organocatalysts were designed: C2-symmetrical thiourea/tertiary amines entirely derived from 2-amino-2-deoxy saccharides, thiourea/primary amines based on pentopyranose and a cyclohexane skeleton, and (thio)urea/tertiary phosphines containing both saccharide and α-amino acid unit. Both functional groups of organocatalysts of the first type are located on the saccharide unit, and it is the only element which fully determines stereoselectivity. This is an exceptional approach as the majority of saccharide-based organocatalysts use saccharide as a bulky electron- withdrawing substituent. However, the...
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