Catalyst‐Enabled Site‐Divergent Stereoselective Michael Reactions: Overriding Intrinsic Reactivity of Enynyl Carbonyl Acceptors

Abstract

Abstract A site‐divergent stereoselective Michael reaction system is developed based on the identification of two distinct catalysts. Cinchonidine‐derived thiourea catalyzes the 1,4‐addition of prochiral azlactone enolates to enynyl N ‐acyl pyrazoles in a highly diastereo‐ and enantioselective manner to give stereochemically defined alkynes, while P ‐spiro chiral triaminoiminophosphorane catalytically controls the stereoselective 1,6‐addition and the consecutive γ‐protonation of the vinylogous enolate intermediate to afford Z , E ‐configured conjugated dienes. This 1,6‐adduct serves as a valuable precursor for the synthesis of a 2‐amino‐2‐deoxy sugar.