cis-diprotected cyclams and cyclens: a new route to symmetrically or asymmetrically 1,4-disubstituted tetraazamacrocycles and to asymmetrically tetrasubstituted derivatives

The use of cyclam and cyclen oxamides as intermediates for the synthesis of N-1,N-4-disubstituted tetraazamacrocycles is reported. This pathway afford s a general strategy for the preparation of symmetrically or asymmetrically disubstituted derivatives in good yields. Also these intermediates proved convenient synthons for the preparation of asymmetrically tetrasubstituted macrocycles, leading to a new class of potentially dinucleating ligands.