Track topics on Twitter Track topics that are important to you
The proline-catalyzed self-condensation of aliphatic aldehydes in DMSO with varying amounts of catalyst was studied by in situ NMR spectroscopy. The reaction profiles and intermediates observed as well as deuteration studies reveal that the proline-catalyzed aldol addition and condensation are competing, but not consecutive, reaction pathways. In addition, the rate-determining step of the condensation is suggested to be the C-C bond formation. Our findings indicate the involvement of two catalyst molecules in the C-C bond formation of the aldol condensation, presumably by the activation of both the aldol acceptor and donor in a Mannich-type pathway. This mechanism is shown to be operative also in the oligomerization of acetaldehyde with high proline amounts, for which the first in situ detection of a proline-derived dienamine was accomplished. In addition, the diastereoselectivity of the aldol addition is evidenced to be time-dependent since it is undermined by the retro-aldolization and the competing irreversible aldol condensation; here NMR reaction profiles can be used as a tool for reaction optimization.
Institut für Organische Chemie, Universität Regensburg , Universitätsstr. 31, D-93053 Regensburg, Germany.
This article was published in the following journal.
Name: The Journal of organic chemistry
Mechanistic study has been carried out on the B(C6F5)3-catalyzed amine alkylation with carboxylic acid. The reaction includes acid-amine condensation and amide reduction steps. In condensation step, t...
Although aldol condensation is one of the most important organic reactions, capable of forming new C-C bonds, its mechanism has never been fully established. It is now concluded that the rate-limiting...
Organocatalyzed Michael, Mannich, and aldol reactions of aldehydes or ketones as nucleophiles have triggered several discussions regarding their reaction mechanism. H218O has been utilized to determin...
A new process has been developed for the copper-catalyzed direct N-arylation of five-membered heterocycles with azoles. Five-membered heterocycles bearing an acetyl group also underwent a Mannich-type...
A new strategy for thiazoles via copper-catalyzed [3+1+1]-type condensation reaction from oximes, anhydrides and potassiumthiocyanate (KSCN) is developed herein. The transformation has good functional...
Proline is a non-essential amino acid that helps with collagen formation. Collagen is one of the main ingredients of skin, bone, tendons, and connective tissue. It is thought that proline ...
The objective of this study is to assess the efficacy, tolerability, safety and pharmacokinetics of IgG with Proline (IgPro) in subjects with PID. The study should evaluate whether the ra...
The purpose of this clinical trial is to investigate the relationship between the gene polymorphism of aldehyde dehydrogenase 2 and contrast induced nephropathy and its mechanism.
This is a randomized, parallel, single center, double masked, vehicle controlled study. The purpose of this study is to determine the activity and safety of NS2 in patients with grass, tre...
Polycythemia Vera (PV) is a disease of bone marrow stem cells that manifests in a drastic increase of red blood cells and frequently also of white blood cells. The "thickening" of the bloo...
Ketonic amines prepared from the condensation of a ketone with formaldehyde and ammonia or a primary or secondary amine. A Mannich base can act as the equivalent of an alpha,beta unsaturated ketone in synthesis or can be reduced to form physiologically active amino alcohols.
The first enzyme of the proline degradative pathway. It catalyzes the oxidation of proline to pyrroline-5-carboxylic acid in the presence of oxygen and water. The action is not reversible. The specific activity of proline oxidase increases with age. EC 1.5.3.-.
Enzymes that catalyze a reverse aldol condensation. A molecule containing a hydroxyl group and a carbonyl group is cleaved at a C-C bond to produce two smaller molecules (ALDEHYDES or KETONES). EC 4.1.2.
Protein domains that are enriched in PROLINE. The cyclical nature of proline causes the peptide bonds it forms to have a limited degree of conformational mobility. Therefore the presence of multiple prolines in close proximity to each other can convey a distinct conformational arrangement to a peptide chain.
A proline analog that acts as a stoichiometric replacement of proline. It causes the production of abnormal proteins with impaired biological activity.