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Alkaloidy kory chinowej : małe cząsteczki, które wiele mogą

Kacprzak K., Czarnecki P.

Wiadomości Chemiczne

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2013

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[Z] 67, 5-6

443--493

EN

Cinchona alkaloids comprising quinine, quinidine, cinchonidine and cinchonine as the major members constitute a unique class of quinoline alkaloids with tremendous impact on human civilization (Section 1). The odyssey of Cinchona alkaloids began with the discovery of their antimalarial properties followed by antiarrhytmic action of quinidine. Currently medicinal chemistry of Cinchona alkaloids derivatives develops rapidly and many other activities such as cytotoxic, multidrug resistance inhibitory have been demonstrated (Section 5) [5]. Beside medicine Cinchona alkaloids gave also the fundaments of stereochemistry and asymmetric synthesis. An extraordinary catalytic potency of parent and modified Cinchona alkaloids (deserving privileged catalyst classification) include more than 50 types of diverse stereoselective reactions, with few spectacular such as asymmetric dihydroxylation of alkenes or heterogeneous α-ketoesters hydrogenation (Section 3) [3]. Last but not least the portfolio of applications of Cinchona alkaloids includes resolution of racemates by diastereomeric crystallization or by the use of Cinchona- -based chiral stationary phases for ion-exchange enantioselective chromatography and other recognition or sensing systems (Section 4) [166]. Easy transformation of Cinchona alkaloids (for example by click chemistry) into other chiral and modular building blocks together with current pressure on a more intense exploration of sustainable products make cinchona alkaloids of primary importance for modern synthetic, catalytic and medicinal chemistry. The aim of this review which covers over 200 references is to briefly summarize all aspects of Cinchona alkaloid chemistry and biology with the special emphasis on new applications.

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Wpływ środowiska achiralnego na rozróżnienie chiralne pochodnych pirolidyno-2-onu w kolumnie cyklodekstrynowej

Górska M., Bielejewska A., Kulig K., Leś A., Widomski P., Żukowski J.

Przemysł Chemiczny

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2012

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T. 91, nr 9

1834-1841

PL

Zbadano retencję i rozdzielenie na enancjomery serii 15 racemicznych pochodnych pirolidyn-2-onu w kolumnie tri(3,5-dimetylolfenylokarboilo)-β-cyklodekstrynowej, stosując zróżnicowany skład fazy ruchomej z jednym lub z dwoma modyfikatorami w układzie fazy normalnej, w fazie odwróconej i w fazie organicznej. Jako modyfikatory w układzie faz normalnych stosowano mieszaninę n-heksanu z etanolem lub 2-propanolem, w układzie faz odwróconych wodę z acetonitrylem, a w polarnej fazie organicznej acetonitryl z kwasem octowym lub acetonitryl z kwasem octowym i trietyloaminą. Zamiana układu faz normalnych na fazy odwrócone spowodowała zmianę kolejności elucji badanych związków. W układzie faz normalnych mieszanina n-heksanu z etanolem powoduje lepsze rozdzielenie enancjomerów niż mieszanina n-heksanu z 2-propanolem. Retencja i enancjoselektywność zależą od pH fazy ruchomej w układzie faz odwróconych. Lepszą separację enancjomerów uzyskano przy niskim pH (ok. 3). Niewielki dodatek trietyloaminy jako drugiego modyfikatora zwiększył sprawność układu i wpłynął na rozdzielenie enancjomerów trzech badanych związków. Znaczący wpływ achiralnych modyfikatorów na rozdział enancjomeskazuje na występowanie silnie zróżnicowanych oddziaływań międzymolekularnych w badanych układach. Podobny wniosek można było wysnuć na podstawie analizy równań QSRR.

EN

Fifteen racemic derivatives of pyrrolidin-2-one were sepd. on a tri(3,5-dimethylphenylcarboilo)-β-cyclodextrin column by using n-hexane/EtOH or n-hexane/Me₂CHOH in normal mobile phases, H₂O/MeCN reversed phases and MeCN/AcOH or MeCN/AcOH/Et₃N org. phases. EtOH was more efficient than Me₂CHOH in normal phases. The addn. of Et₃N resulted in an improvement of sepn. in reversed phase, where the best results were achieved at pH 3.

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Zastosowanie ekstrakcji i technik membranowych do rozdziału stereoizomerów aminokwasów i ich pochodnych

Dżygiel P., Wieczorek P. P.

Wiadomości Chemiczne

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2004

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[Z] 58, 11-12

941--962

EN

Derivatives of amino acids are known from their great biological relevance, for example can be used as pharmaceuticals, crop protection substances or food additives. In significant number of cases such substances show their biological potency only as single enantiomer. Therefore, one of the most important conditions during their production is to ensure their high optical purity. Generally, two routes to accomplish this goal are considered to be most effective. The first one is to synthesize enantiomers with the support of chiral catalyst introduced into the reaction mixture. The second approach involves the preparation of racemic mixture and in final step to separate it into single enantiomers. Considering the separation the most popular methods are enantiomers crystallization in the form of diastereoisomeric salts and chromatographic separation of racemates with application of chiral stationary phases. However, despite of their very extensive use, those methods possess several drawbacks and limitations. Among them, the most inconvenient are large use of solvents and expensive, chiral substances acting as agents responsible for the enantioseparation. Additionally, in case of chromatography some problems with non-linearity of the chromatographic process can take place. Therefore, the study on alternative ways of achieving the efficient separation of enantiomers is carried out in many laboratories. In this review, the very promising methods of the stereoisomers separation namely extraction and membrane techniques are presented and discussed. In case of extraction the examples of classical liquid - liquid extraction as well as aqueous - aqueous extraction and solid phase extraction application for amino acids enantiomers and their derivatives separation are described. The special attention is paid on the use of membrane techniques. The brief overview of applications of different membrane processes for the same purpose including the use of chiral polymer membranes, molecularly imprinted membranes, achiral membranes with chiral agents (solution free or immobilized) and liquid membranes is also presented. Finally, the examples of preparative scale processes, in which extraction and membrane techniques were used, are also discussed to show their applicability for the production of amino acids and their derivatives with high amounts and optical purity.