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The Michael reaction can occur under neutral conditions through an enamine.
The Stork enamine synthesis is named in his honor.
The enamine eliminates sodium bisulfite with formation of naphthylamine 6.
Hajos and Parrish proposed the enamine mechanism in their paper .
The enamine will cyclize and dehydrate to give the desired quiniline (5).
Its high reactivity reflects that it is an enamine, which enhances the electron-donating ability of the ring.
This compound is deprotonated to the imine 5b or the enamine 5c but an equilibrium exists between both species.
An enamine is a cousin of an enone, with the carbonyl replaced by an amine group.
Proline enters a catalytic cycle by reacting with the aldehyde to form an enamine.
Enamines derived from piperidine can be used in the Stork enamine alkylation reaction.
Enamine focuses on three main technologies:
An additional methyl group attached to proline forces a specific enamine approach and the transition state now is a 10-membered ring with addition in anti-mode.
The Stork enamine reaction involves the conjugate addition of enamines to conjugated carbonyls.
The first step is the formation of an enamine 2 using N,N-dimethylformamide dimethyl acetal and pyrrolidine.
The amine and acetaldehyde produce the enamine, which subsequently reacts with sodium nitroprusside to the imine.
This enamine catalysis method is a type of organocatalysis, since the catalyst is entirely based on a small organic molecule.
An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine.
The active species is the hexafluoropropylamine; any enamine is converted into this by the hydrogen fluoride byproduct as the reaction proceeds.
The reaction is also diastereoselective because the enamine addition occurs with a preference for trans addition without formation of the cis isomer.
The amount of enamine in the product depends on temperature control during the reaction - the higher the temperature the more enamine.
The sequence can be also be performed without the pyrrolidine, via the N,N-dimethyl enamine, though reaction times may be much longer in some cases.
The word "enamine" is derived from the affix en-, used as the suffix of alkene, and the root amine.
The immediate reaction product is an nucleophilic enamine and the reaction cascades with abstraction of chlorine from a chlorinated quinone.
In the initial enamine formation, dimethylamine (a gas) is displaced by pyrrolidine from the dimethylformamide dimethylacetal, producing a more reactive reagent.
There is no danger of an achiral background reaction because the transient enamine intermediates are much more nucleophilic than their parent ketone enols.