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Propargylic-Amines and Alcohols Through anti-Selective Mannich and Aldol Reactions
1 , 2 , 1 , 1 , 1 , 3 , 2 , 1 , 1 , 2 , 1 , 1 , * 1
1  Departamento de Química Orgánica I, Facultad de Química, Universidad del País Vasco, Manuel Lardizabal 3, 20018 Donostia, Spain
2  Departamento de Química Aplicada, Universidad Pública de Navarra, Campus de Arrosadía, 31006 Pamplona, Spain
3  Departamento de Química Fundamental, Universidad de A Coruña, E-15071 A Coruña, Spai


Herein we present a practical and selective route to synthetically usefull propargylic amines and alcohols.[1] The key of both approaches is the combined use of an α,α-dialkylprolinol ether catalyst and a Brønsted acid that leads to adducts with high levels of diastereo- and enantiocontrol (anti/syn up to 90:10, ee up to 95%).  In the aldol addition it was  also observed that the presence of CuI as a third catalyst component, generally provided an increase in reaction diastereoselectivity (anti/syn up to 95:5). This study uncovers a new case of chiral enamine catalysis in which α,α-dialkylprolinol silyl ethers perform better than their parent α,α-diaryl analogs. The resulting densely funcionalyzed adduts may be transformed into  more complex systems taking advantage of the chemistry of the triple bond.


Keywords: Propargylic amides and alcohols; Diastereoselectivity; Chiral enamine catalysis