Selective N,N-functionalisation of cyclam: crystal structure of the Cu2+ complex of 1,4,8,11-tetra-azacyclotetradecane-1,8-diacetic acid and the tricyclic lactam 15,18-dioxo-1,5,8,12-tetra-azatricyclo[10.2.2.25.8]tetradecane

Abstract

A general synthetic method for the synthesis of 1,8-disubstituted derivatives of the 14-membered tetra-aza macrocycle, ‘cyclam’, involves selective ditosylation: in the Cu²⁺ complex of the 1,8-diacetic acid derivative, the copper is six-co-ordinate with elongated Cu–O interactions and this macrocycle undergoes lactamisation to form a paracyclophane-like tricyclic lactam which is resistant to acidic hydrolysis.