PROCESS FOR PREPARING CROSS-BRIDGED TETRAAZA MACROCYCLES

摘要

The present invention relates to a process for preparing a cross-bridged tetraaza macrocyclic ligand having formula (I) wherein each R is independently C1-C8 linear or branched alkyl, -(CH2)xCO2M, and mixtures thereof; provided both of the R units are not methyl; M is hydrogen or a salt forming cation; x is from 1 to 6; each index n is independently from 0 to 3; by contacting a di-quaternary cis tetracycle precursor with hydrogen in the presence of a palladium catalyst in an aqueous solution having a pH of at least about 10 at a temperature of about 40 DEG C to about 100 DEG C.