Intermediate formation of anilines in the synthesis of Schiff bases from nitroarenes and aldehydes

The role of the intermediate formation of anilines in the synthesis of Schiff bases from nitroarenes, aldehydes and CO catalysed by metal complexes has been investigated. Contrary to earlier belief, the reaction does not proceed through the reaction of an intermediate nitrene with the carbonyl compound, but by reduction of the nitroarene by CO and traces of water to initially afford the aniline, which then reacts with the aldehyde to afford the Schiff base, regenerating the water necessary to reduce more nitroarene. (C) 1999 Elsevier Science B.V. All rights reserved.