Preparation of N,O-aminals as synthetic equivalents of H 2 CNAr and (H 2 CNHAr) + ions: neutral- and acid-promoted transformations

A general method for the synthesis of N,O-aminals derived from primary aromatic amines is described. The reactivity of these compounds under neutral and acidic conditions has been studied and the title compounds can be envisaged as general purpose H2CNAr or (H2CNHAr)+ equivalents. N,O-Aminals have been converted into perhydrotriazines by moderate heating and into bis(4-aminoaryl)methane derivatives or N-benzylarylamines, respectively when heated in acidic media with pH control. Reduction of N,O-acetals with sodium cyanoborohydride has revealed that the C–O bond is broken exclusively in acidic media.