Stork enamine alkylation

The Stork reaction is a reaction name in the field of organic chemistry. It was named after the Belgian-born chemist Gilbert Stork and is a variant of the Michael addition. While in the Michael addition with an enolate α, β -unsaturated ketones or aldehydes is converted to 1,5- dicarbonyls, an enamine is used, the ketone to the α -carbon to be substituted here, instead of the enolate anion.

Reaction mechanism

Representation of the enamine

The amine as a nucleophile attacks the carbonyl carbon of the ketone. The resulting alcoholate ion is protonated and by donation of a proton by the protonated amine produces a neutral tetrahedral intermediate. By re- protonation of water is eliminated. In the last step the double bond of the enamine is then formed.

The remainder ( R = a primary or secondary alkyl, allyl, benzyl, propargyl, CH ₂ CO ₂ R, CH ₂ CN) of the halogenated hydrocarbon is attached to the enamine. In an acid hydrolysis now the previously added within the pyrrolidine enamine formation is eliminated again. Deprotonation produced the α -substituted ketone.

Variants

As a reactant of the enamines can, for example, also oxiranes, acrylonitrile or 2,4- Dintrochlorbenzol be used.