Bimorpholines as Alternative Organocatalysts in Asymmetric Aldol Reactions

Asymmetric organocatalytic aldol condensation is discussed on the basis of intramolecular and inter-molecular reactions. In addition to the widely used proline and its derivatives an application of the new type of the organocatalyst – bimorpholines in the above-mentioned reactions is described. The new catalyst has a unique C2-symmetric skeleton with four acceptor sites that makes it stereoselective and efficient. Small changes in the structure of the catalyst lead to a remarkable loss of selectivity

ChemInform Abstract: Bimorpholines as Alternative Organocatalysts in Asymmetric Aldol Reactions

Asymmetric organocatalytic aldol condensation is discussed on the basis of intramolecular and inter-molecular reactions. In addition to the widely used proline and its derivatives an application of the new type of the organocatalyst – bimorpholines in the above-mentioned reactions is described. The new catalyst has a unique C2-symmetric skeleton with four acceptor sites that makes it stereoselective and efficient. Small changes in the structure of the catalyst lead to a remarkable loss of selectivity

3,3'-Bimorpholine derivatives as a new class of organocatalysts for asymmetric michael addition

New N-alkyl-3,3'-bimorpholine derivatives (iPBM) were revealed to be efficient organocatalysts for the asymmetric direct Michael addition of aldehydes to nitroolefins and a vinyl sulfone. In these transformations using iPBM, 1,4-adducts were afforded in high yields, with good to high levels of diastereo- and enantioselectivity. The stereochemical outcome of the reaction could be explained by an acyclic synclinal model

Diastereoselective Multicomponent Cascade Reaction Leading to [3.2.0]-Heterobicyclic Compounds

A general three-component triple cascade reaction through an iminium–enamine–iminium sequential activation initiated by a hetero-Michael addition to α,β-unsaturated aldehydes affords [3.2.0]­heterobicycles in high diastereoselectivity. The rate and diastereoselectivity of the reaction depended on the (<i>E</i>)-4-heterocrotonate and size of the secondary amine. The enantiomers of the major diastereoisomer of oxa- and azabicyclo[3.2.0]­heptane derivatives were separated by enzymatic kinetic resolution with immobilized <i>Candida antarctica</i> Lipase B (CALB), with <i>E</i> values up to 153. The absolute configuration of the nonacylated enantiomer of oxabicyclo[3.2.0]­heptane was determined by single crystal X-ray analysis

Diastereoselective Multicomponent Cascade Reaction Leading to [3.2.0]-Heterobicyclic Compounds

A general three-component triple cascade reaction through an iminium–enamine–iminium sequential activation initiated by a hetero-Michael addition to α,β-unsaturated aldehydes affords [3.2.0]­heterobicycles in high diastereoselectivity. The rate and diastereoselectivity of the reaction depended on the (<i>E</i>)-4-heterocrotonate and size of the secondary amine. The enantiomers of the major diastereoisomer of oxa- and azabicyclo[3.2.0]­heptane derivatives were separated by enzymatic kinetic resolution with immobilized <i>Candida antarctica</i> Lipase B (CALB), with <i>E</i> values up to 153. The absolute configuration of the nonacylated enantiomer of oxabicyclo[3.2.0]­heptane was determined by single crystal X-ray analysis