Direct catalytic asymmetric Mannich-type reactions of isomerizable aliphatic imines: chemoselective enolate formation from a hydroxyketone by a Zn-catalyst

A novel homobimetallic nickel complex for the asymmetric direct Mannich reaction of imines: a practical method on a multi-gram scale

A practical asymmetric direct Mannich reaction catalyzed by a homobimetallic nickel complex with a low catalyst loading on a preparative scale.

Dinuclear zinc catalyzed asymmetric spirannulation reaction: an umpolung strategy for formation of α-alkylated-α-hydroxyoxindoles

A highly diastereo- and enantioselective formal [3 + 2] cycloaddition of α,β-unsaturated esters and 3-hydroxyoxindoles catalyzed by a dinuclear zinc-ProPhenol complex is reported. The stereoselective Michael additions of 3-hydroxyoxindoles and the subsequent transesterifications afford spirocyclic δ-lactones.

Enantioselective synthesis of homoallylic amines through reactions of (pinacolato)allylborons with aryl-, heteroaryl-, alkyl-, or alkene-substituted aldimines catalyzed by chiral C1-symmetric NHC-Cu complexes

A catalytic method for enantioselective synthesis of homoallylamides through Cu-catalyzed reactions of stable and easily accessible (pinacolato)allylborons with aryl-, heteroaryl-, alkyl-, or alkenyl-substituted N-phosphinoylimines is disclosed. Transformations are promoted by 1-5 mol % of readily accessible NHC-Cu complexes, derived from C(1)-symmetric imidazolinium salts, which can be prepared in multigram quantities in four steps from commercially available materials. Allyl additions deliver the desired products in up to quantitative yield and 98.5:1.5 enantiomeric ratio and are amenable to gram-scale operations. A mechanistic model accounting for the observed selectivity levels and trends is proposed.

Ba-Catalyzed Direct Mannich-Type Reactions of a β,γ-Unsaturated Ester Providing β-Methylaza-Morita−Baylis−Hillman-Type Products

Barium-catalyzed direct Mannich-type reactions of a beta,gamma-unsaturated ester are described. The Ba-catalyst not only promoted the Mannich-type reactions, but also isomerized Mannich adducts to afford beta-methyl aza-Morita-Baylis-Hillman-type products in 61-88% yield from various aryl, heteroaryl, and alkyl imines. Preliminary trials on enantioselective variants with a chiral biaryldiol ligand gave products in up to 80% ee.