How is 1,4,7,10-Tetraazacyclododecan-1-ylacetic acid (CAS: 170454-90-7) typically synthesized?

1,4,7,10-Tetraazacyclododecan-1-ylacetic acid (CAS: 170454-90-7) is synthesized through the condensation of 1,4,7,10-tetraazacyclododecane with acetic anhydride. The reaction is catalyzed by a trace amount of a Lewis acid such as aluminum chloride. The yield is typically high, and the product is isolated by recrystallization from a suitable solvent. The process requires careful control of the reaction conditions to achieve high selectivity and purity.