Hemiaminal

Semiaminals (synonym: Halbaminoacetal ) are a group of substances in organic chemistry. They contain as structural element a hydroxy group and an amino group on the same carbon atom.

Aminals (including aminoacetals ) are a group of substances, which contain as functional groups, two groups bonded to a carbon atom of the amino groups. Aminals are mostly unstable and intermediates in the formation of imines.

Aminals and semiaminals are relatives of Acetals and hemiacetals, wherein the oxygen groups are replaced by nitrogen groups. The cyclic aminals include representatives of the 3- oxazolines and 4- oxazolines.

Representation

The following reaction shows an example of forming a hemiaminal from a secondary amine and formaldehyde carbazole.

Aminals of primary amines are unstable and can not be directly observed often. This usually requires special conditions.

The formation of hemiaminals is a key step in the asymmetric synthesis of saxitoxin:

In this step, the double bond is oxidized to the first intermediate acyloin osmium (III) chloride, ozone, and sodium carbonate -. Synthesis of 3- oxazolines described in the literature.