One-Stage Monosubstitution in Cyclen - Two Novel Examples

Two new routes for alkylsubstituton of one in four amino groups in 1,4,7,10-tetraazacyclododecane (cyclen) are described, isomeric N-tris(hydroxy)butylcyclens 4 and 6 have been obtained in very good yields. Further carboxymethylation of other three amino groups afforded 10-tris(hydroxy)butyl-1,4,7-tris(carboxymethyl)cyclens 1 and 2.