Regioselective Base‐Promoted Nucleophilic Ring Opening of Spirocyclic 2,6‐Dioxopiperazines: Synthesis of N‐(1‐Carboxycyclohexyl)amino Acid Derivatives

Amino acid derived spirocyclic 2,6‐dioxopiperazines are easily and regioselectively opened by base‐promoted nucleophilic attack of hydroxide or H2O on the less crowded carbonyl group at C‐6 to give N‐(1‐carbamoylcyclohexyl)amino acid derivatives. However, the imide group of the 2,6‐dioxopiperazine ring is rather unreactive toward alcohols, alkoxides, and amines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)