Exploring Supramolecular Gels in Flow-Type Chemistry - Design and Preparation of Stationary Phases

Two major challenges facing chemical synthesis are product isolation and catalyst recovery. One method to overcome these challenges is to perform the synthesis in a flow system with a catalytic stationary phase. However, the polymeric catalytic materials used in flow systems are often laborious to produce. In this study, we investigate a novel supramolecular gel as a catalytic stationary phase material. The gel is based on a modular, easy to synthesize, oxotriphenylhexanoate (OTHO) gelator comprised of a catalytic unit designed to catalyze the Knoevenagel reaction. The catalytic organogel enhances the rate of product formation and can be reused five times. Use of the OTHO to construct catalytic gels is a flexible technique that can be utilized to improve product isolation and reduce wastage of the catalyst

Polycyclizations of Ketoesters: Synthesis of Complex Tricycles with up to Five Stereogenic Centers from Available Starting Materials

Here we present a polycyclization of oxotriphenylhexanoates. The polycyclization is governed by electronic effects, and three major synthetic paths have been established leading to stereochemically complex tricyclic frameworks with up to five stereogenic centers. The method is compatible with an array of functional groups, allowing pharmacophoric elements to be introduced post cyclization

Synthesis of cis-Oriented Vicinal Diphenylethylenes through a Lewis Acid-Promoted Annulation of Oxotriphenylhexanoates

This study explores the synthesis of cyclic cis-vicinal phenyl ethylenes from oxotriphenylhexanoates. The reaction is a BBr3-promoted cyclization of 1,6-ketoesters (1) to five-membered diketo compounds (2). The synthesis is interesting as it constitutes one of the few examples of modular stereoselective synthesis of structures with a cis-oriented vicinal diphenylethylene. The core structure of 2 can be smoothly derivatized, which makes it a promising synthetic building block for further stereoselective synthetic applications

Use of hypervalent ionide compounds and MBH carbonates in organocatalysis

Beside transition-metal and enzymatic catalysis plays organocatalysis an important role in asymmetric organic sythesis. In the field of organocatalysis are amines group of compounds commonly used as organocatalysts. This thesis deals with the use of hypervalent iodine compounds in combination with amine catalysis and also with the use of Morita-Baylis-Hillman carbonates in organocatalytic allylic substitution reactions. In the first part an organocatalytic enantioselective α-selenylation reaction of saturated aldehydes using diphenyldiselenide and iodobenzene diacetate is described. Reaction is catalysed by commercially available first generation MacMillan catalyst. The products of the reaction were obtained in yields of 51-70 % and enantiomeric excess 95-99 %. Designed methodology was extended on the derivatives of β-ketoesters by catalysis of tertiary amines and quaternary ammonium salts. Apart from selenylation reactions we have also dealt with the possibility of formation C-C bond using hypervalent iodine compouds. Particularly, we focused on electrophillic alkynylation reactions of appropriate nucleophiles using acetylene-bearing hypervalent iodine compounds. Fluorinated sulfone derivatives and enolizable heterocycles such as pyrazolone derivatives, rhodanines, oxindoles and azlactones were..

Isolation of pigments from yellow pepper and their identificiation by NMR spectroscopy.

Katedra učitelství a didaktiky chemieDepartment of teaching and Didactics of ChemistryFaculty of SciencePřírodovědecká fakult

Organocatalytic asymmetric synthesis of various organic compounds from α,β-unsaturated aledyhes

With regard to a fast development in the field of fluoroorganic chemisty, the intention of this diploma thesis is focused to utilize of organocatalysis by secondary amines as catalysts for preparation enantiomerically pure compounds containing fluorine atom in its structure. The preparation of these subsances is realized by way of nucleofilic addition to α,β- unsaturated aldehydes using suitable fluorine containing nuclephilic agent 1-(fluoronitromethylsulphonyl)benzene, to get appropriate 1,4-adduct

Highly enantioselective fluoromalonate addition to ?,?-unsaturated aldehydes

A highly enantioselective organocatalytic fluoromalonate addition to ?,?-unsaturated aldehydes is reported. The reaction is catalyzed by simple and commercially available secondary amines, affording the corresponding 1,4-adducts with high yields and enantioselectivities

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