A self-catalyzed aza-Henry addition of ethyl nitroacetate on N-alkyl trifluoromethyl aldimines was reported to synthesize β-amino α-nitro trifluoromethyl esters, precursors of α,β-diamino acid derivatives. In the presence of a resident chiral center on the imine nitrogen, the use of a suitable Lewis acid leads to a good stereofacial control, always resulting from a nucleophilic unlike attack. By starting from optically pure N-protected trifluoromethyl aldimines or directly from N-α-amino ester trifluoromethyl aldimines, small ψ[CH(CF3)NH]-peptidomimetic backbones can be achieved in which a new primary amine function represents a possible center for synthetic extension. Finally, a very interesting, and never observed before, palladiumcatalyzed syn β-elimination occurred, leading to the selective nitro group reduction reaction on the syn-α-amino ester functionalized aza-Henry adducts and obtaining more stable optically pure trifluoromethyl conjugated imines.
Ethyl nitroacetate in Aza-Henry addition on trifluoromethyl aldimines: a solvent-free procedure to obtain chiral trifluoromethyl α,β-diamino esters / Parise, Luca; Pelagalli, Alessia; Pellacani, Lucio; Sciubba, Fabio; Vergari, MARIA CECILIA; Fioravanti, Stefania. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - STAMPA. - 81:7(2016), pp. 2864-2874. [10.1021/acs.joc.6b00136]
Ethyl nitroacetate in Aza-Henry addition on trifluoromethyl aldimines: a solvent-free procedure to obtain chiral trifluoromethyl α,β-diamino esters
PELAGALLI, ALESSIA;PELLACANI, Lucio;SCIUBBA, FABIO;VERGARI, MARIA CECILIA;FIORAVANTI, Stefania
2016
Abstract
A self-catalyzed aza-Henry addition of ethyl nitroacetate on N-alkyl trifluoromethyl aldimines was reported to synthesize β-amino α-nitro trifluoromethyl esters, precursors of α,β-diamino acid derivatives. In the presence of a resident chiral center on the imine nitrogen, the use of a suitable Lewis acid leads to a good stereofacial control, always resulting from a nucleophilic unlike attack. By starting from optically pure N-protected trifluoromethyl aldimines or directly from N-α-amino ester trifluoromethyl aldimines, small ψ[CH(CF3)NH]-peptidomimetic backbones can be achieved in which a new primary amine function represents a possible center for synthetic extension. Finally, a very interesting, and never observed before, palladiumcatalyzed syn β-elimination occurred, leading to the selective nitro group reduction reaction on the syn-α-amino ester functionalized aza-Henry adducts and obtaining more stable optically pure trifluoromethyl conjugated imines.File | Dimensione | Formato | |
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