Facile isolation of bisimines based on 3,3’-diaminobenzidine: Direct access to unsymmetrical bimetallic salphen building blocks
S. Curreli, E. C. Escudero-Adán, J. Benet-Buchholz, A. W. Kleij
J. Org. Chem. 2007, 72, 7018-7021
Abstract: Diimines obtained from 3,3'-diaminobenzidine and tert-butyl-substituted salicylaldehydes in MeOH can be readily isolated in 60-90% yield and were obtained as a mixture of geometrical isomers. Two distinct diimine intermediates (4 and 5) with a higher molecular symmetry as related to the other isomeric diimine products were both isolated by crystallization of which 5 was subsequently used to demonstrate that nonsymmetrical bis-salphen complexes with different functional groups and metal centers can be assembled via a three-component one-pot procedure.