Enamine

Enamines are unsaturated chemical compounds which are formed by reaction of aldehydes or ketones with secondary amines (such as pyrrolidine, piperidine or morpholine ), and subsequent elimination of water (H2O). With the use of primary amines or ammonia, the tautomeric equilibrium is not on the side of Enamines, but on the side of imine (see keto -enol tautomerism ). You have the basic shape R1R2C = CR3 NR4R5, where Rx is for a radical.

The term " enamine " arises from the prefix " s " (indicating the alkene contained, similar to " enol ") and " amine ", which is attached to the alkene as a functional group.

One of the radicals R4 or R5 on the nitrogen is a hydrogen atom, then the enamine is a tautomeric form of the corresponding imine. Then the two forms ( enamine -imine tautomerism ) face in an equilibrium reaction. A similar reaction is the keto -enol tautomerism. In both reactions, the hydrogen atom changes places between the heteroatom (oxygen or nitrogen ) and the second carbon atom:

The simplest enamine (all residues are composed of hydrogen atoms) vinyl amine.

Use

Enamines are in the synthesis of chemical compounds is important because the Ladungsaufspreizung a facile reaction of electrophiles allows in the mesomeric system at the second carbon atom (e.g., acid chlorides and activated alkylating agents such as allylic halides and α -halo carboxylic acid esters as well as electron-deficient alkenes ).

Note also

• Enamine alkylation and acylation
• Thorpe- Ziegler reaction
• Stork enamine reaction
• Enamine lactone rearrangement
• Michael addition (which may be performed with enamines )
• Nucleophilic addition