Alkylimino-de-oxo-bisubstitution

Alkylimino-de-oxo-bisubstitution in organic chemistry is the organic reaction of carbonyl compounds with amines to imines. The reaction name is based on the IUPAC Nomenclature for Transformations. The reaction is acid catalyzed and the reaction type is nucleophilic addition of the amine to the carbonyl compound followed by transfer of a proton from nitrogen to oxygen to a stable hemiaminal or carbinolamine. With primary amines water is lost in an elimination reaction to an imine. With aryl amines especially stable Schiff bases are formed.

The reaction steps are reversible reactions and the reaction is driven to completion by removal of water by azeotropic distillation, molecular sieves or titanium tetrachloride. Primary amines react through an unstable hemiaminal intermediate which then splits off water.

Secondary amines do not lose water easily because they do not have a proton available and instead they often react further to an aminal:

or when an α-carbonyl proton is present to an enamine:

In acidic environment the reaction product is an iminium salt by loss of water.

This reaction type is found in many Heterocycle preparations for example the Povarov reaction and the Friedländer-synthesis to quinolines.