Propargylic-Amines and Alcohols Through anti-Selective Mannich and Aldol Reactions

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.