Application of amines for the preparation of chiral cyclic compounds

Organocatalysis, along with catalysis by metal complexes or enzymes, has become one of the very useful tools of asymmetric synthesis. Different activation modes or their combinations into sequences (domino reactions) enable effective access to enantiomerically enriched complex substances. The objective of this work was the preparation of chiral molecules from simple precursors activated by amine-based organocatalysts. In particular, we were focused on a study of asymmetric allyl substitution of Morita-Baylis-Hillman carbonates and two-component domino reactions on sulfur-containing heterocycles. The thesis deals with the organocatalytic allyl amination of Morita-Baylis-Hillman carbonates with aromatic amines catalyzed by β-isocupreidine. The corresponding allylic amines were obtained in high yields (90-96%) with moderate enantiomeric excess. It was possible to get substances of high optical purity (ee 82-99%) by recrystallization of selected products. Furthermore, the developed method was applied in the preparation of enantiomerically enriched β-lactams, which represent valuable precursors, for example, in the synthesis of the drug Ezetimibe. The second part of the work is focused on stereoselective cyclization reactions comprising selected sulfur heterocycles. Although the cyclization reaction of...Organokatalýza se zařadila spolu s katalýzou kovovými komplexy nebo enzymy mezi velmi užitečné nástroje asymetrické syntézy. Různé aktivační módy nebo jejich vhodné kombinace do sekvencí (domino reakce) umožňují efektivní přístup k enantiomerně obohaceným komplexním látkám. Předmětem této práce byla příprava chirálních molekul z jednoduchých prekurzorů aktivovaných organokatalyzátory na bázi aminů. Jednalo se zejména o studium asymetrické allylové substituce Morita-Baylis-Hillmanových karbonátů a dále dvoukomponentních domino reakcí na heterocyklech obsahujících síru. V práci je pojednáváno o organokatalytické allylové aminaci Morita-Baylis- Hillmanových karbonátů aromatickými aminy za katalýzy β-isokupreidinem. Odpovídající allylové aminy byly získány ve vysokých výtěžcích (90-96 %) s průměrným enantiomerním přebytkem. Pomocí rekrystalizace vybraných produktů se podařilo získat látky vysoké optické čistoty (ee 82-99 %). Dále byla vyvinutá metoda aplikována na přípravu enantiomerně obohacených β-laktamů, které představují hodnotné prekurzory například pro syntézu látky ezetimib. Druhá část práce se zabývá stereoselektivními cyklizačními reakcemi na vybraných sirných heterocyklech. Po neuspokojivých výsledcích studia cyklizační reakce alkyliden-N- fenylrhodaninu s aromatickým hydroxyenalem se...Department of Organic ChemistryKatedra organické chemieFaculty of SciencePřírodovědecká fakult

Optimalization of preparation of bifunctional organocatalysts derived from alkaloids

This bachelor thesis deals with the preparation of C−9 Cinchona alkaloid derivatives, which are used in wide variety of asymmetric transformations. First goal is comparison of synthetic aproaches and their effectiveness. In particular of C−9 amino derivatives. This part also examines possible optimization of synthesis individual steps. Second goal of bachelor thesis focuses on preparation bifunctional catalysts based on Cinchona alkaloids

Organocatalytic reactions leading to functionalized cyclic compounds

First part is focused on finding suitable reaction conditions for organocatalytic domino Michael/Michael reaction of ethyl (E)-3-(2-thiophenyl)acrylate with α,β-unsaturated aldehydes. Second part deals with the preparation of pyrazolone derivatives from commercially available compounds and describes effects of various substituents in α-position on chemical efficiency and stereoselectivity of amination with azodicarboxylate catalyzed by quinine

Organocatalytic amination of pyrazolones with azodicarboxylates: scope and limitations

The organocatalytic amination of pyrazol-5-ones with azodicarboxylates (catalyzed by quinine) is reported. This asymmetric process furnishes enantiomerically enriched hydrazine adducts containing quaternary stereocenters in high yields (74–96 %) and enantioselectivities (up to ee 97 %). Theoretical calculations allow us to propose the relations between quinine catalyst and reactants leading to observed stereochemical outcome and trends in the effectivity of the reaction.</p

Correction: Synergistic formal ring contraction for the enantioselective synthesis of spiropyrazolones (Chemical Science (2018) 9 (6368-6373) DOI: 10.1039/C8SC00913A)

The authors regret that a citation related to a previous Michael addition/Trost allylation cascade reaction was omitted at the end of the sentence beginning "With the advent of organocatalysis." The full reference is presented herein as ref. 1. The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.</p

correction synergistic formal ring contraction for the enantioselective synthesis of spiropyrazolones

Correction for 'Synergistic formal ring contraction for the enantioselective synthesis of spiropyrazolones' by Marta Meazza et al., Chem. Sci., 2018, 9, 6368–6373