suma/proline

Cellulose nanofibers (CNFs) have recently attracted much attention as catalysts in various reactions. Organocatalysts have emerged as sustainable alternatives to metal-based catalysts in green organic synthesis, with concerted systems containing CNFs that are expected to provide next-generation

[reaction: see text] Here we describe the proline-catalyzed Michael addition of unmodified ketones to nitro olefins. This novel reaction provides gamma-nitro ketones in modest enantioselectivity yet excellent yields.

A practical four-step synthesis of 3-alkyl-, vinyl-, and aryl-substituted proline derivatives, which are important building blocks for conformationally restrained peptide analogs, was developed. The method relies on a Cu-catalyzed 1,4-addition of Grignard reagents to N-protected 2,3-dehydroproline

l-Proline was immobilized onto mesoporous silica through direct synthesis method via morphosynthesis possessing short channels and plugs in the pore structure which provided chiral enhancement in the diethyl malonate addition reaction.

Excellent yields and at least 95 % ee can be achieved for the addition of dimethyl malonate to cycloalkenyl acetates by using a palladium complex of the new phosphanyldihydrooxazole ligand L as a catalyst (see scheme). The ligand L can be synthesized from commercially available trans

The effect of proline on refolding and unfolding kinetics as well as activity of lipase from Pseudomonas fluorescens was determined using stopped-flow fluorescence and UV/Vis absorbance spectroscopy. Enzyme assay at different concentrations of proline revealed that activity of enzyme reaches maximum

Chiral ionic liquids with a focus on their applications in asymmetric Michael additions and related reactions were reviewed. The examples were classified on the basis of the mode of asymmetric induction (e.g., external induction/non-covalent interaction or internal induction/covalent bond

[reaction: see text] Lanthanide triflates along with proline-derived ligands have been found to be efficient catalysts for enantioselective conjugate addition of nucleophilic radicals to enoates. N-Acyl oxazolidinones, when used as achiral additives, gave meaningful enhancements in the ees for the

A new chiral entity, pentanidium, has been shown to be an excellent chiral phase-transfer catalyst. The enantioselective Michael addition reactions of tert-butyl glycinate-benzophenone Schiff base with various α,β-unsaturated acceptors provide adducts with high enantioselectivities. A successful

Nitroalkanes add to cyclic and acyclic enones in an enantioselective manner in the presence of catalytic quantities of L-proline and trans-2,5-dimethylpiperazine as excess additive.

5-Pyrrolidin-2-yltetrazole performs as a useful organocatalyst for the asymmetric addition of malonates to a range of enones, with good to excellent enantioselectivities.

Aromatic β-hydroxyaldehydes, 1,3-diols, and α,β-unsaturated aldehydes are valuable precursors to biologically active natural products and drug molecules. Herein we report the biocatalytic aldol condensation of acetaldehyde with various aromatic aldehydes to give a number of aromatic α,β-unsaturated

[reaction: see text] 9-Tosyl-3,4-dihydro-beta-carboline reacted with 3-ethyl-3-buten-2-one in the presence of (S)-proline to give (3R,12bR)-3-ethyl-12-tosyl-3,4,6,7,8,9,10,11,12,12b-decahydro-1H-indolo[2,3-a]quinolizin-2-one in complete enantio- and diastereoselectivity. The compound thus obtained

Isoleucine-catalyzed direct enantioselective aldol additions between enolizable aldehydes are reported. Intermediate acetal structures dictate the configurative outcome and were supported by a hydrogen bond. This direct isoleucine-catalyzed aldol addition represents a welcome complement to both

The asymmetric direct aldol addition of acetone to aliphatic aldehydes catalyzed by D-proline, L-proline, and its derivatives was studied. While excellent results could be obtained in neat acetone using alpha-branched aldehydes, unbranched and beta-branched aldehydes gave moderate results. Two