The Cinchona Primary Amine-Catalyzed Asymmetric Epoxidation and Hydroperoxidation of α,β-Unsaturated Carbonyl Compounds with Hydrogen Peroxide

Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogen peroxide as the oxidant, we have developed highly enantioselective Weitz–Scheffer-type epoxidation and hydroperoxidation reactions of α,β-unsaturated carbonyl compounds (up to 99.5:0.5 er). In this article, we present our full studies on this family of reactions, employing acyclic enones, 5–15-membered cyclic enones, and α-branched enals as substrates. In addition to an expanded scope, synthetic applications of the products are presented. We also report detailed mechanistic investigations of the catalytic intermediates, structure–activity relationships of the cinchona amine catalyst, and rationalization of the absolute stereoselectivity by NMR spectroscopic studies and DFT calculations

Direct Asymmetric α Benzoyloxylation of Cyclic Ketones

It's amine business: A readily available cinchona‐derived primary amine is an effective catalyst for the direct asymmetric α benzoyloxylation of cyclic ketones (see scheme; Bz=benzoyl). This efficient and highly enantioselective method uses inexpensive benzoyl peroxide as the oxygen source and stoichiometric amounts of the ketone, and expands the current set of methodologies to directly access valuable protected 2‐hydroxyketone derivatives

Catalytic Asymmetric Epoxidation of α-Branched Enals

An asymmetric catalytic epoxidation of α-branched, α,β-unsaturated aldehydes is presented. A highly synergistic combination of a primary cinchona-based amine and a chiral phosphoric acid was found to promote the reaction with excellent enantiocontrol for α-monosubstituted and α,β-disubstituted enals

Organocatalytic asymmetric α-benzoyloxylation of α-branched aldehydes and enals: a useful approach to oxygenated quaternary stereocenters

Direct asymmetric α-benzoyloxylation of α-branched aldehydes and α-branched enals via enamine and dienamine catalysis was used to construct quaternary oxygenated stereocenters with good yields and moderate to good enantioselectivity. This method uses an inexpensive and readily available cinchona alkaloid-derived primary amine as the catalyst, benzoyl peroxide as the oxygen source, and stoichiometric amounts of the aldehyde substrates, providing simple metal-free access to valuable protected 2-hydroxyaldehyde derivatives