9 research outputs found
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