title: Enantioselective organocatalytic reduction of β-trifluoromethyl nitroalkenes: an efficient strategy for the synthesis of chiral β-trifluoromethyl amines.
abstract: An efficient organocatalytic stereoselective reduction of β-trifluoromethyl-substituted nitroalkenes, mediated by 3,5-dicarboxylic ester-dihydropyridines (Hantzsch ester type), has been successfully developed. A multifunctional thiourea-based (S)-valine derivative was found to be the catalyst of choice, promoting the reaction in up to 97% ee. The methodology has been applied to a wide variety of substrates, leading to the formation of differently substituted precursors of enantiomerically enriched β-trifluoromethyl amines. The mechanism of the reaction and the mode of action of the metal-free catalytic species were computationally investigated; on the basis of DFT transition-state (TS) analysis, a model of stereoselection was also proposed.
authors.affiliation: Dipartimento di Chimica, Universita' degli Studi di Milano via Golgi 19, 20133 Milano (Italy), Fax: (+39) 0250314159.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Massolo
authors.forename: Maurizio
authors.initials: M
authors.lastname: Benaglia
authors.forename: Manuel
authors.initials: M
authors.lastname: Orlandi
authors.forename: Sergio
authors.initials: S
authors.lastname: Rossi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Celentano
mesh_terms: D000475:Alkenes / Q000138:chemical synthesis* / Q000737:chemistry; D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D004952:Esters; D006845:Hydrocarbons, Fluorinated / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009574:Nitro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013890:Thiourea / Q000737:chemistry*
chemical_list: D000475:Alkenes; D000588:Amines; D004952:Esters; D006845:Hydrocarbons, Fluorinated; D009574:Nitro Compounds; D013890:Thiourea
keywords: bifunctional catalyst; chiral fluorinated amines; nitroalkenes; reduction; trifluoromethyl derivatives