| abstract |
An improved process for preparing 1,1'- 1,4-phenylenebis-(methylene)!-bis-1,4,8,11-tetraazacyclotetradecane comprising the selective functionalization of an acyclic tetraamine, and subsequent dimerization and hydrolyzation/tosylation to obtain a 1,4-phenylenebis-methylene bridged hexatosyl acyclic precursor in a first step, the cyclization of said precursor to obtain a hexatosyl cyclam dimer in a second step, and the detosylation of said cyclam dimer in a third step followed by basification to obtain the desired 1,1'- 1,4-phenylenebis-(methylene)!-bis-1,4,8,11-tetraazacyclotetradecane. |