A concise synthesis procedure to furnish multi-gram amounts of hexadentate, bivalent DO2A-based chelators

The synthesis of three bifunctional chelators, namely 1,7-bis-(4-aminobenzyl)-1,4,7,10-tetraaza-cyclododecane-4,10-diacetic acid (1), 1,7-bis-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-4,10-diacetic acid (2) and 1,7-bis-(4-maleimidobenzyl)-1,4,7,10-tetraazacyclododecane-4,10-diacetic acid (3), is presented. Compounds 1–3 are versatile building blocks for the synthesis of bivalent imaging agents for molecular imaging. This straightforward, high yielding synthesis route affords 1–3 on a multi-gram scale.