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Upstream product

• 1631-26-1 1-benzyl-1H-pyrrole-2,5-dione 
• 78-84-2 isobutyraldehyde 

Relevant academic research and scientific papers

Chitosan as a chiral ligand and organocatalyst: Preparation conditions-property-catalytic performance relationships

Chitosan is an abundant and renewable chirality source of natural origin. The effect of the preparation conditions by alkaline hydrolysis of chitin on the properties of chitosan was studied. The materials obtained were used as ligands in the ruthenium-catalysed asymmetric transfer hydrogenation of aromatic prochiral ketones and oxidative kinetic resolution of benzylic alcohols as well as organocatalysts in the Michael addition of isobutyraldehyde to N-substituted maleimides. The degrees of deacetylation of the prepared materials were determined by 1H NMR, FT-IR and UV-vis spectroscopy, the molecular weights by viscosity measurements, their crystallinity by WAXRD, and their morphology by SEM and TEM investigations. The materials were also characterized by Raman spectroscopy. The biopolymers which have molecular weights in a narrow (200-230 kDa) range and appropriate (80-95%) degrees of deacetylation were the most efficient ligands in the enantioselective transfer hydrogenation, whereas in the oxidative kinetic resolution the activity of the complexes and the stereoselectivity increased with the degree of deacetylation. The chirality of the chitosan was sufficient to obtain enantioselection in the Michael addition of isobutyraldehyde to maleimides in the aqueous phase. Interestingly, the biopolymer afforded the opposite enantiomer in excess compared to the monomer, d-glucosamine. In this reaction, good correlation between the degree of deacetylation and the catalytic activity was found. These results are novel steps in the application of this natural, biocompatible and biodegradable polymer in developing environmentally benign methods for the production of optically pure fine chemicals.

1,2-Diamine-Derived (thio)Phosphoramide Organocatalysts in Asymmetric Michael Additions

Phosphoramides and thiophosphoramides were prepared from optically pure C2-symmetric 1,2-diamines and were used as chiral organocatalysts in the asymmetric Michael additions of aldehydes and ketones to N-substituted maleimides. The 1,2-diphenylethane-1,2-diamine derived thiophosphoramide, which could be prepared in good yield in a one-step procedure, was found to be more active and selective catalyst in the addition of aldehydes to various maleimide derivatives, when compared to sulfonamides having the same backbone. Products resulted in reactions of ketones with maleimides were also obtained in high yields and enantioselectivities. The thiophosphoramide derivative was also efficient in the asymmetric conjugate addition of carbonyl compounds to β-nitrostyrene and in the reaction of nitromethane with α,β-unsaturated ketones. Based on results obtained with (thio)phosphoramides in asymmetric additions to maleimides it was suggested that a weaker, more flexible hydrogen-bonding of the rigid electrophile to the catalyst is responsible for the improved performance of these bifunctional organocatalysts, as compared with sulfonamides. (Figure presented.).

Design of Heterogeneous Organocatalyst for the Asymmetric Michael Addition of Aldehydes to Maleimides

Asymmetric Michael additions of isobutyraldehyde to maleimides catalyzed by optically pure diamines and their sulfonamides were investigated to develop heterogeneous chiral catalysts for these reactions. Encouraging results, i. e. complete transformations

Organocatalytic enantioselective conjugate addition of aldehydes to maleimides in deep eutectic solvents

The conjugate enantioselective addition of aldehydes, mainly α,α-disubstituted, to maleimides leading to enantioenriched succinimides, has been achieved in recyclable deep eutectic solvents at room temperature. Enantiomerically pure carbamate-monoprotecte

Asymmetric Michael addition of aldehydes to maleimides in primary amine-based aqueous ionic liquid-supported recyclable catalytic system

A primary amine-based aqueous ionic liquid-supported recyclable catalytic system for asymmetric Michael addition of aldehydes to maleimides has been developed. The best enantioselectivity (up to 84% ee) was attained at the [bmim]BF4/water 2: 1 (v/v) ratio.

Highly enantioselective Michael addition of α,α-disubstituted aldehydes to maleimides catalyzed by new primary amine-squaramide bifunctional organocatalysts

New bifunctional primary amine-squaramides catalyzed asymmetric Michael addition reaction of α,α-disubstituted aldehydes to maleimides has been developed. This organocatalytic asymmetric reaction provides easy access to functionalized succinimides with a

Solvent-induced reversal of enantioselectivity in the synthesis of succinimides by the addition of aldehydes to maleimides catalysed by carbamate-monoprotected 1,2-diamines

A simple change in the polarity of the solvent allows both enantiomers of substituted succinimides to be obtained in the enantioselective conjugate addition reaction of aldehydes, mainly disubstituted, to maleimides catalysed by chiral carbamate-monoprote

Primary Amine-2-Aminopyrimidine Chiral Organocatalysts for the Enantioselective Conjugate Addition of Branched Aldehydes to Maleimides

Chiral primary amines containing the (R,R)- and (S,S)-trans-cyclohexane-1,2-diamine scaffold and a pyrimidin-2-yl unit are synthesized and used as general organocatalysts for the Michael reaction of α-branched aldehydes to maleimides. The reaction takes place with 10 mol% organocatalyst loading and hexanedioic acid as cocatalyst in aqueous N,N-dimethylformamide at 10 °C affording the corresponding succinimides in good yields and enantioselectivities. DFT calculations support the stereochemical results and the role played by the solvents.

Highly enantioselective michael addition promoted by a new diterpene-derived bifunctional thiourea catalyst: A doubly stereocontrolled approach to chiral succinimide derivatives

A doubly stereocontrolled organocatalytic asymmetric Michael addition to the synthesis of substituted succinimides is described. Starting from aldehydes and maleimides, both enantiomers of the succinimides could be obtained in high to excellent yields (up

Calixarene-based chiral primary amine thiourea promoted highly enantioselective asymmetric Michael reactions of α,α-disubstituted aldehydes with maleimides

Calix[4]arene based chiral bifunctional thiourea-primary amines have been shown to act as effective catalysts for the Michael addition of aldehydes to maleimides for the first time. The corresponding adducts were generally obtained preferentially in (R)-