Highly efficient asymmetric aldol reaction in brine using a fluorous sulfonamide organocatalyst

Dipeptide-catalysed Michael reaction under physiological conditions: Examination of potential bioorthogonality

Reactions for drug synthesis under cell-like conditions or even inside living cells can potentially be used e.g., to minimize toxic side effects, to maximize bioactive compound efficacy and/or to address drug delivery problems. Those reactions should be bioorthogonal to enable the generation of drug-like compounds with sufficiently good yields. In the known bioorthogonal Michael reactions, using thiols and phosphines as nucleophiles (e.g., in CS and CP bond formation reactions) is very common. No bioorthogonal Michael addition with a carbon nucleophile is known yet. Therefore, the development of such a reaction might be interesting for future drug discovery research. In this work, the metal-free Michael addition between cyclohexanone and various trans-β-nitrostyrenes (CC bond formation reaction), catalysed by a dipeptide salt H-Pro-Phe-O-Na+, was investigated for the first time in the presence of glutathione (GSH) and in phosphate-buffered saline (PBS). We demonstrated that with electron-withdrawing substituents on the aromatic ring and in β-position of the trans-β-nitrostyrene yields up to 64% can be obtained under physiological conditions, indicating a potential bioorthogonality of the studied Michael reaction. In addition, the selected Michael products demonstrated activity against human ovarian cancer cells A2780. This study opens up a new vista for forming bioactive compounds via CC bond formation Michael reactions under physiological (cell-like) conditions.

A Simple and Efficient Protocol for Proline-Catalysed Asymmetric Aldol Reaction

The proline-catalysed asymmetric aldol reaction is usually carried out in highly dipolar aprotic solvents (dimethylsulfoxide, dimethylformamide, acetonitrile) where proline presents an acceptable solubility. Protic solvents are generally characterized by poor stereocontrol (e.g., methanol) or poor reactivity (e.g., water). Here, we report that water/methanol mixtures are exceptionally simple and effective reaction media for the intermolecular organocatalytic aldol reaction using the simple proline as the catalyst.

Asymmetric Conjugate Additions of Carbonyl Compounds to Nitroalkenes under Solvent-Free Conditions Using Fluorous Diaminomethylenemalononitrile Organocatalyst

The novel fluorous organocatalyst bearing a diaminomethylenemalononitrile motif is prepared. The fluorous organocatalyst efficiently promotes asymmetric conjugate additions of ketones to nitroalkenes and results in high yields of these addition products with excellent enantioselectivities under solvent-free conditions.

Binaphthyl-based chiral bifunctional organocatalysts for water mediated asymmetric List–Lerner–Barbas aldol reactions

Binaphthyl-based organocatalysts were synthesized and successfully applied to the asymmetric List–Lerner–Barbas aldol reaction in water medium. These organocatalysts were found to be effective catalysts for the reactions of ketones with different aldehydes to give aldol products with higher yield and ee's.

Aerobic photooxidative direct asymmetric aldol reactions of benzyl alcohols using water as the solvent

We report an aerobic photooxidative direct asymmetric aldol reaction using water as the solvent.

Enhancement of stereoselectivities in asymmetric synthesis using fluorinated solvents, auxiliaries, and catalysts

In this review, the drastic changes using fluorinated solvents, additives, auxiliaries, and catalysts in catalytic asymmetric transformations are presented.

Highly modular dipeptide-like organocatalysts for direct asymmetric aldol reactions in brine

The dipeptide-like organocatalysts have been developed for asymmetric aldol reactions in brine to achieve high yields and enantioselectivities with 1 mol% catalyst-loading.

Asymmetric aldol reaction organocatalyzed by bifunctional N-prolyl sulfinamides under solvent-free conditions

Chiral bifunctional N-prolyl sulfinamide and its TFA salts were synthesized and applied in asymmetric aldol reactions under solvent-free conditions. The aldol adducts were obtained with high to excellent yields, enantioselectivities and diastereoselectivities. A matching effect between chiral proline and sulfinamide moieties was observed for the catalysts.

Perfluoroalkanesulfonamide organocatalysts for asymmetric conjugate additions of branched aldehydes to vinyl sulfones

Asymmetric conjugate additions of branched aldehydes to vinyl sulfones promoted by sulfonamide organocatalyst 6 or 7 have been developed, allowing facile synthesis of the corresponding adducts with all-carbon quaternary stereocenters in excellent yields with up to 95% ee.