Chiral Primary Amine Tagged to Ionic Group as Reusable Organocatalyst for Asymmetric Michael Reactions of C‐Nucleophiles with α,β‐Unsaturated Ketones

Abstract

AbstractThe first primary amine‐derived organocatalyst modified with an ionic group for asymmetric Michael reactions of C‐nucleophiles with α,β‐unsaturated ketones was synthesized. In the presence of this catalyst and an acidic co‐catalyst (AcOH), hydroxycoumarin and its sulfur‐containing analogue reacted with benzylideneacetone derivatives or cyclohexenone to afford the corresponding Michael adducts in high yields (up to 97%) and with reasonable enantioselectivity (up to 80%). The catalyst could be easily recovered and efficiently reused three times, afterwards, its activity and stereodifferentiating ability gradually declined. The analysis of recovered catalyst samples by ESI‐MS allowed us to detect undesirable side reactions that poisoned the catalyst, and propose an approach for its reactivation.