Abstract A new easy??to??run route to cyclen, homocyclen, and cyclam is proposed, based on the cyclization with dibromo??or ditosyloxy??derivatives of bisaminal intermediates obtained by condensation of the appropriate linear tetraamine with cyclohexanedione. In the cyclization step, the use of cesium carbonate instead of potassium carbonate as proton trapper caused a remarkable increase of yields.
