title: Ethyl Nitroacetate in Aza-Henry Addition on Trifluoromethyl Aldimines: A Solvent-Free Procedure To Obtain Chiral Trifluoromethyl α,β-Diamino Esters.
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, palladium-catalyzed 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.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" , P.le Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Parise
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" , P.le Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Pelagalli
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" , P.le Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Lucio
authors.initials: L
authors.lastname: Pellacani
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" , P.le Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Sciubba
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" , P.le Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Maria Cecilia
authors.initials: MC
authors.lastname: Vergari
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Roma "La Sapienza" , P.le Aldo Moro 5, I-00185 Roma, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Fioravanti