rac-2,2′-Bipiperidine-1,1′-diium dibromide

In the title compound, C10H22N2 2+·2Br−, a precursor in the synthesis of organocatalysts, the bipiperidinium ion is located on a twofold rotation axis which passes through the mid-point of the central C—C bond. The piperidinium ring adopts a chair conformation. In the crystal, the cations are linked together by Br− ions through N—H⋯Br hydrogen bonds, forming layers parallel to the ab plane

Protocol for the preparation of primary amine-containing catalysts on the resin

Summary: In light of escalating sustainability concerns, addressing catalyst usage and waste production challenges becomes crucial. Here, we introduce a robust protocol for crafting recyclable polystyrene-supported primary amines, providing a promising solution via heterogeneous catalysis. The protocol details immobilization onto insoluble resins through ester, ether, or amide bonds, facilitating the synthesis of heterogeneous catalysts with diverse organic components.For complete details on the use and execution of this protocol, please refer to Kanger et al.1 : Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics

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

Primary amines as heterogeneous catalysts in an enantioselective [2,3]-Wittig rearrangement reaction

Summary: A series of heterogeneous catalysts anchored to different polystyrene-based supports has been prepared and applied in an asymmetric [2,3]-Wittig rearrangement reaction of cyclohexanone derivatives. Among them, primary amino acid-derived (aminomethylated)polystyrene-supported catalysts showed excellent reactivity leading to the formation of rearranged products in good enantioselectivities of both diastereomers. Reusability issues connected to the deactivation of the catalyst were proved to be dependent on the end-capping strategy chosen for the blocking of the unreacted active sites of the resin. This issue of end-capping has not previously been in focus. Using bulkier pivaloyl end-capping moiety, we were able to recycle the catalyst in six consecutive cycles with only marginal deceleration of the reaction. Moreover, the epimerization of the product that occurred while conducting a rearrangement reaction in the presence of a homogeneous catalyst was almost fully eliminated by switching the catalytic system to heterogeneous

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