The highly efficient asymmetric Michael addition reactions of cyclopentanone with chalcones were catalyzed by a simple and commercially available chiral 1,2-diaminocyclohexane-hexanedioic acid, and exhibited good yields (up to 92%) and excellent enantioselectivities (up to 99% ee). A new di-iminium mechanism for the reaction was proposed.

A novel strategy for highly efficient utilization of chiral ammonium salt catalysts has been described in this paper. Three kinds of catalytic functions including iminium catalysis, enamine catalysis, and acid catalysis of chiral ammonium salt catalysts, have been achieved in the enantioselective reduction and alkylation reaction of α,β-unsaturated aldehydes with alcohols.

The palladium hydride-iminium complex generated from Pd/C and triethylamine catalyses the isomerisation of allylic alcohols into carbonyl compounds, and Pd/C catalyses the conjugate reduction of activated double bonds using triethylamine as the source of the two newly incorporated hydrogen atoms via the same complex.

[structure: see text]. The concise total synthesis of securinine in nine steps from readily available starting materials is described. Key steps of the synthesis include an addition of a silyloxyfuran to an in situ generated iminium ion and a novel ring closing metathesis reaction.

An efficient and broadly applicable alternative to the classical Pictet-Spengler synthesis of tetrahydro-β-carbolines is presented. The method relies on metal-catalyzed isomerization of allylic amines to form reactive iminium intermediates which can be trapped by a tethered indole nucleophile.

In the presence of a Brønsted acid catalyst, both aldehydes and N-Boc-aminals were converted to enecarbamates and N-Boc-iminium salts as activated nucleophiles and electrophiles, respectively, giving unprecedented Mannich adducts. The asymmetric variant of the present Mannich reaction has also been demonstrated with a chiral phosphoric acid catalyst.

The title compound, C(13)H(10)BrNO(2), crystallizes in a zwitterionic form. The zwitterion exists in a trans configuration about the C=N bond and is almost planar, the dihedral angle between the two benzene rings being 2.29 (9)°. An intra-molecular N-H⋯O hydrogen bond formed between the iminium NH(+) and the phenolate O(-) atoms generates an S(6) ring motif. In the crystal, the zwitterions are ...

Abstract The application of biocatalysis in conquering challenging synthesis requires the constant input new enzymes. Developing novel biocatalysts by absorbing catalysis modes from synthetic chemistry has yielded fruitful new‐to‐nature Organocatalysis was originally bio‐inspired and become third pillar asymmetric catalysis. Transferring organocatalytic reactions back to enzyme platforms is a p...