title: Development of a syn-Selective Mannich Reaction of Aldehydes with Propargylic Imines by Dual Catalysis: Asymmetric Synthesis of Functionalized Propargylic Amines.
abstract: Direct coupling of enolizable aldehydes with C-alkynyl imines is realized affording the corresponding propargylic Mannich adducts of syn configuration, thus complementing previous methods that gave access to the anti-isomers. The combination of proline and a urea Brønsted base cocatalyst is key for the reactions to proceed under very mild conditions (3-10 mol % catalyst loading, dichloromethane as solvent, -20 °C, 1.2 molar equivalents of aldehyde) and with virtually total stereocontrol (syn/anti ratio up to 99:1; ee up to 99 %). Some possibilities of further chemical elaboration of adducts are also briefly illustrated.
authors.affiliation: Departamento de Química Orgánica I, Universidad del País Vasco UPV/EHU, Manuel Lardizabal 3, 20018, San Sebastián, Spain.
authors.forename: Irati
authors.initials: I
authors.lastname: Lapuerta
authors.affiliation: Departamento de Química Orgánica I, Universidad del País Vasco UPV/EHU, Manuel Lardizabal 3, 20018, San Sebastián, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Vera
authors.affiliation: Departamento de Química Orgánica I, Universidad del País Vasco UPV/EHU, Manuel Lardizabal 3, 20018, San Sebastián, Spain.
authors.forename: Mikel
authors.identifier: 0000-0003-0362-0136
authors.initials: M
authors.lastname: Oiarbide
authors.affiliation: Departamento de Química Orgánica I, Universidad del País Vasco UPV/EHU, Manuel Lardizabal 3, 20018, San Sebastián, Spain. claudio.palomo@ehu.es.
authors.forename: Claudio
authors.identifier: 0000-0001-9809-2799
authors.initials: C
authors.lastname: Palomo
keywords: Mannich reaction; aminoalcohols; asymmetric catalysis; dual catalysis; propargylic amines