Michael Reaction Of Aldehydes Research Articles

Discussion Addendum for: Asymmetric Michael Reaction of Aldehydes and Nitroalkenes

Discussion Addendum for: Asymmetric Michael Reaction of Aldehydes and Nitroalkenes

Front Cover: Asymmetric Michael Reaction of Aldehydes and Dicyanoalkenes Catalyzed by Diphenylprolinol Silyl Ether (Eur. J. Org. Chem. 48/2018)

Front Cover: Asymmetric Michael Reaction of Aldehydes and Dicyanoalkenes Catalyzed by Diphenylprolinol Silyl Ether (Eur. J. Org. Chem. 48/2018)

ChemInform Abstract: Molecular Assembly of an Achiral Phosphine and a Chiral Primary Amine: A Highly Efficient Supramolecular Catalyst for the Enantioselective Michael Reaction of Aldehydes with Maleimides.

A combined catalyst system of a cinchonidine-derived primary amine and triphenylphosphine (CDNH 2 /PPh 3 ) exhibited high catalytic performance in the Michael reaction of aldehydes with maleimides, thereby affording the corresponding functionalized aldehydes in excellent yields (up to 99%) and enantioselectivities (>99% ee). More interestingly, the significance of the phosphine in enhancing the enantioselectivities in the chiral-primary-amine-catalyzed Michael reaction was revealed. Furthermore, we explored the origin of the reaction mechanism in the Michael addition promoted by the dual organocatalytic system. On the basis of experimental results and spectroscopic analysis, such as UV/Vis, fluorescence emission (FL), NMR, and circular dichroism (CD) spectroscopy, as well as ESI-MS, we found that the molecular assembly of phosphine and primary amine played a crucial role in this enantioselective reaction, in which a possible supramolecular complex was formed as an effective chiral catalyst through noncovalent molecular interactions of a cinchona alkaloid-derived primary amine with triphenylphosphine.

THE REACTION MECHANISMS OF ALDEHYDES AND NITROSTYRENE CATALYZED BY A CHIRAL SILYLATED PYRROLIDINE CATALYST

The asymmetric Michael reaction of aldehydes and nitrostyrene catalyzed by a new (S)-tertbutyl-diphenyl-silyl-pyrrolidine catalyst has been investigated by using density functional theory calculations. The Re face of the enamine is effectively shielded, because of the bulky 2-substituent group on the pyrrolidine ring. For acetaldehyde, there are two different conformers of enamines. Based on the two conformers of enamines, four different reaction pathways have been considered. The calculated enantiomeric excess value is 80.27% in favor of the (R)-configuration product. For propanal, eight different reaction pathways have been considered and the eight corresponding transition states have been located. The calculated enantiomeric excess value is 98.96% in favor of the (2S, 3R)-configuration product. These calculated results are in good agreement with the experimental observations. In addition, the calculations also show that both the used solvent and the enamines play important roles in determining the stereochemical outcome of the product.

Molecular Assembly of an Achiral Phosphine and a Chiral Primary Amine: A Highly Efficient Supramolecular Catalyst for the EnantioselectiveMichael Reaction of Aldehydes with Maleimides

A combined catalyst system of a cinchonidine-derived primary amine and triphenylphosphine (CD-NH2 /PPh3 ) exhibited high catalytic performance in the Michael reaction of aldehydes with maleimides, thereby affording the corresponding functionalized aldehydes in excellent yields (up to 99 %) and enantioselectivities (>99 % ee). More interestingly, the significance of the phosphine in enhancing the enantioselectivities in the chiral-primary-amine-catalyzed Michael reaction was revealed. Furthermore, we explored the origin of the reaction mechanism in the Michael addition promoted by the dual organocatalytic system. On the basis of experimental results and spectroscopic analysis, such as UV/Vis, fluorescence emission (FL), NMR, and circular dichroism (CD) spectroscopy, as well as ESI-MS, we found that the molecular assembly of phosphine and primary amine played a crucial role in this enantioselective reaction, in which a possible supramolecular complex was formed as an effective chiral catalyst through noncovalent molecular interactions of a cinchona alkaloid-derived primary amine with triphenylphosphine.

ChemInform Abstract: Organocatalytic Asymmetric anti‐Selective Michael Reactions of Aldehydes and the Sequential Reduction/Lactonization/Pauson—Khand Reaction for the Enantioselective Synthesis of Highly Functionalized Hydropentalenes.

AbstractIn the presence of DBU and the prolinol derivative, unsaturated aldehydes undergo asymmetric anti‐selective Michael addition to malonates of type (VI).

Anti-Selective Michael Reaction of Aldehydes

<i>anti</i>-Selective Michael Reaction of Aldehydes