Michael addition is one of the most important carbon–carbon bond formation reactions. In this study, an (R, R)-1,2-diphenylethylenediamine (DPEN)-based thiourea organocatalyst was applied to asymmetric nitroalkenes and cycloketones produce a chiral product. The primary amine moiety in DPEN reacts with ketone form enamine activated through hydrogen between nitro group ?, ?-unsaturated nitroalken...

Differences in the kinetic behavior of aldol reactions compared to aminoxylation and amination reactions are rationalized by consideration of the ratedetermining step in each case. Both autoinductive behavior and the rate-enhancing effect of additives are attributed to an effect on the enamine formation step.

“Click” chemistry has become an efficient avenue to unimolecular polymeric nanoparticles through the self-crosslinking of individual polymer chains containing appropriate functional groups. Herein we report the synthesis of ultra-small (7 nm in size) polymethyl methacrylate (PMMA) nanoparticles (NPs) by the “metal-free” cross-linking of PMMA-precursor chains prepared by reversible addition-frag...

Enantioselective direct Michael additions of ketones using (S)-1-(2-pyrrolidinylmethyl)-pyrrolidine as a catalyst are described. Michael adducts with up to 91% e.e. were obtained by the reaction of alkylidene malonates with simple unactivated ketones under mild reaction conditions. © 2001 Elsevier Science Ltd. All rights reserved. An increasing demand for optically active compounds has stimulat...

The catalytic a-alkylation of carbonyl compounds is a common approach in organic synthesis. In recent years, many efforts have been directed towards the activation of ketones and aldehydes by means of enamine catalysis to react with a broad range of electrophiles. In 2004, List reported an elegant intramolecular alkylation of aldehydes with alkyl halides using proline-based amine catalysts. Whi...

An efficient amine-/ruthenium-catalyzed three-step process for the synthesis of Nefopam analogues was achieved through combinations of cascade enamine amination/iso-aromatization/allylation and diene or enyne metathesis as key steps starting from functionalized Hagemann's esters. In this communication, we discovered the application of ruthenium-catalysis on olefins containing free amines withou...

An enamine intermediate is believed to be the central feature of biological catalysts, such as aldolases and small molecule amine organocatalysts. Despite decades of investigation of naturally occurring aldolase enzymes and recent studies on designed aldolase antibodies and organocatalysts, direct structural observation of an enamine intermediate has proven to be rare. Herein, we report the obs...

Michael addition is an important reaction because it can be used to synthesize a wide range of natural products or complex compounds that exhibit biological activities. In this study, mirror image aldehyde and α,β-unsaturated nitroalkene were reacted in the presence (R,R)-1,2-diphenylethylenediamine (DPEN). Herein, thiourea was introduced as organic catalyst, selective carried out. The primary ...

The enzyme 4-oxalocrotonate tautomerase (4-OT), which has a catalytic N-terminal proline residue (Pro1), can promiscuously catalyze various carbon-carbon bond-forming reactions, including aldol condensation of acetaldehyde with benzaldehyde to yield cinnamaldehyde, and Michael-type addition of acetaldehyde to a wide variety of nitroalkenes to yield valuable γ-nitroaldehydes. To gain insight int...

Protonation of gossypol Schiff bases (S1 and S2), possessing different numbers of basic N-atoms, was studied using potentiometric, spectroscopic, ESI MS and PM5 methods. Titration of S1 and S2 with HClO(4), monitored by the FT-IR and (1)H NMR, indicated that the change from the enamine-enamine into the protonated imine-imine tautomeric form occurs at different Schiff base-H(+) ratio. The FT-IR ...