Unusual enantioselectivities in heterogeneous organocatalyzed reactions: Reversal of direction using proline di- versus tri-peptides in the aldol addition

Autor:	Mónika Fekete, Mihály Bartók, Csaba Somlai, György Szőllősi, Antal Csámpai
Rok vydání:	2014
Předmět:	Chemistry Process Chemistry and Technology Enantioselective synthesis Cyclohexanone Tripeptide Heterogeneous catalysis Medicinal chemistry Catalysis chemistry.chemical_compound Aldol reaction Organocatalysis Organic chemistry Physical and Theoretical Chemistry Enantiomeric excess
Zdroj:	Journal of Molecular Catalysis A: Chemical. 382:86-92
ISSN:	1381-1169
DOI:	10.1016/j.molcata.2013.11.011
Popis:	The heterogeneous asymmetric direct aldol reactions between aldehydes (2-nitrobenzaldehyde, 2-methylpropanal) and ketones (acetone, cyclohexanone) in the presence of polystyrene (PS) resin supported di- and tripeptides were studied under otherwise identical experimental conditions at room temperature in batch reactor. For all three asymmetric aldol reactions reversal of enantiomeric excess was observed on H-Pro-Pro-Glu(OH)-PS catalyst (ee 39–50%) as compared to the H-Pro-Glu(OH)-PS catalyst (ee 52–95%). The determinant role of the conformation of the intermediate adducts held responsible for chiral induction is interpreted by quantum chemical calculations.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::baa4642efa9ee4accc06f30a6a740c13 https://doi.org/10.1016/j.molcata.2013.11.011 Zobrazit plný text záznamu Full Text from ScienceDirect