Monofunctionalized Tetraazacrowns for Use in Bioconjugation and Catalysis

Abstract

Alkylation of 1,4,7,11‐tetraazacyclododecane (cyclen) with 4‐nitrobenzyl bromide, p‐chloromethylbenzyl alcohol, 4‐iodobenzyl bromide, or 4‐vinylbenzyl bromide in acetonitrile gave N‐monoalkylated cyclen ligands 1–4 in 38–60% yield. Compounds 3 and 4 reacted with cobalt chloride hexahydrate in methanol, followed by air oxidation and addition of HCl, gave cobalt complexes dichloro{N‐(4‐iodobenzyl)‐1,4,7,10‐tetraazacyclotetradecane}cobalt(III) chloride (5) and dichloro{N‐(4‐vinylbenzyl)‐1,4,7,10‐tetraazacyclotetradecane}cobalt(III) chloride (6) in 34–55% yield. Compounds 1–6 were characterized by 1H NMR, ESI‐MS, UV‐visible, and IR spectroscopies.