NEW METHOD FOR THE SYNTHESIS OF NONSYMMETRIC DINUCLEATING LIGANDS BY AMINOMETHYLATION OF PHENOLS AND SALICYLALDEHYDES

Monoaminomethylated phenols 5-7 and symmetrically diaminomethylated ph enols 8 and 9 were prepared in a one-step procedure-from p-cresol, for maldehyde, and a variety of secondary amines by making use of the arom atic Mannich reaction. Nonsymmetric diaminomethylated phenols 10 and 1 1 were prepared by a sequential aromatic Mannich reaction using p-cres ol, formaldehyde, and two different secondary amines. Alternatively, n onsymmetric diaminomethylated phenols 20-24 were prepared by aminometh ylation of 5-methylsalicylaldehyde followed by Ca) condensation with a primary amine and subsequent reduction or (b) reductive amination wit h a secondary amine. Monoami-nomethylated and (non)symmetric diaminome thylated phenols are excellent ligands for the synthesis of mono- and dinuclear transition metal complexes as is illustrated by the isolatio n of mononuclear iron(III) complex 25 and nonsymmetric dinuclear coppe r(II) complex 26.