The synthesis of an isopropyl substituted 1,4,7-triazacyclononane via an in situ sequential macrocyclisation method.

Using L-valine methyl ester hydrochloride as starting material, the synthesis of (2S)-2-isopropyl-1,4,7-trimethyl-1,4,7-triazacyclononane is described. Various standard Richman-Atkins cyclisation methods gave only poor yields in the key macrocyclisation step. Efficient macrocyclisation yields were, however, realised when an in situ sequential cyclisation method was developed.