99% ee).1,2 Using this methodology, enantiopure baclofen and phenibut (analogs of GABA) have been synthesized.2 Polymer-supported organocatalysts constitute a great challenge for the Michael reaction. In the current study, we report the immobilization of amine-thiourea catalysts containing (1S,2S)- or (1R,2R)-diphenylethylenediamine and tert-butyl aspartate, on various polymer supports, either directly or through spacer units. The solidsupported catalysts evaluated in the reaction between acetone and β- nitrostyrene and highlighted the importance of the choice of the polymer as well as the presence of the spacer or not. The direct attachment of the primary amine-thiourea-aspartate to a crosslinked polystyrene-divinyl benzene resin containing a uniform distribution of aminomethyl groups provides a supported catalyst that affords the product of the reaction between acetone and β-nitrostyrene quantitatively and in high enantioselectivity (91% ee).. Types: Text (Conference or workshop item (Poster)), Text. Subjects: άνθρακας, χημεία" />
Polymer-supported thiourea catalysts for enantioselective Michael reaction
δείτε την πρωτότυπη σελίδα τεκμηρίου στον ιστότοπο του αποθετηρίου του φορέα για περισσότερες πληροφορίες και για να δείτε όλα τα ψηφιακά αρχεία του τεκμηρίου*
Polymer-supported thiourea catalysts for enantioselective Michael reaction
Kokotos, G.
Fotaras, S.
Ferderigos, N.
Among the large number of reactions involving the formation of carbon-carbon bond, the addition of ketones to nitroolefins is a powerful tool for the synthesis of γ-nitro-carbonyl compounds, useful intermediates for pharmaceutical industry. Our recently reported primary amine-thioureas based on tert-butyl esters of natural amino acids exhibit excellent performance for the Michael reaction of ketones with nitroolefins providing the products quantitatively and almost stereospecifically (>99% ee).1,2 Using this methodology, enantiopure baclofen and phenibut (analogs of GABA) have been synthesized.2 Polymer-supported organocatalysts constitute a great challenge for the Michael reaction. In the current study, we report the immobilization of amine-thiourea catalysts containing (1S,2S)- or (1R,2R)-diphenylethylenediamine and tert-butyl aspartate, on various polymer supports, either directly or through spacer units. The solidsupported catalysts evaluated in the reaction between acetone and β- nitrostyrene and highlighted the importance of the choice of the polymer as well as the presence of the spacer or not. The direct attachment of the primary amine-thiourea-aspartate to a crosslinked polystyrene-divinyl benzene resin containing a uniform distribution of aminomethyl groups provides a supported catalyst that affords the product of the reaction between acetone and β-nitrostyrene quantitatively and in high enantioselectivity (91% ee).
*Η εύρυθμη και αδιάλειπτη λειτουργία των διαδικτυακών διευθύνσεων των συλλογών (ψηφιακό αρχείο, καρτέλα τεκμηρίου στο αποθετήριο) είναι αποκλειστική ευθύνη των αντίστοιχων Φορέων περιεχομένου.
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