ChemInform Abstract: Expeditious N-Monoalkylation of 1,4,7,10-Tetraazacyclododecane (Cyclen) via Formamido Protection.

Abstract The reaction of cyclen 1 with chloral hydrate afforded exclusively 1,4,7-triformylcyclen 2 in high yield; the triprotected macrocycle was easily alkylated with various electrophiles in good to excellent yields. The alkaline removal of the formyl groups provided a selective entry into N-monosubstituted cyclen derivatives.