The catalytic oxidation of amines to imines is of intense current interest, owing to the importance of imines as pivotal intermediates in the synthesis of fine chemicals and numerous biologically active compounds. Whereas considerable efforts had been made to develop efficient methods for the oxidation of secondary amines to imines, little attention had until recently been given to the oxidation of primary amines, probably because the generated imines are intermediate products that are easily dehydrogenated to nitriles. A surge of activity in this area originated with the discovery of new catalytic systems that allow the oxidation of primary amines to imines under green conditions. This microreview focuses on the major achievements during the last five years.

A series of 8-alkylamino-5,7-dihydroxyflavones was prepared from chrysine via a seven step sequence. The synthesis of their 6-alkylamino isomers could be subsequently accomplished through a convenient extension of the Wessely-Moser rearrangement. These compounds were found to be efficient neuroprotective agents in vitro.

Metalloenzyme-like catalytic systems oxidize amines to imines under environmentally friendly conditions.