How is 2,8-Diazaspiro[4.5]decane (CAS: 176-67-0) typically synthesized?

2,8-Diazaspiro[4.5]decane can be synthesized via the reaction of 4,8-diamino-1,3,5,7,9-decaphenoxazine with acetic acid under basic conditions. The method involves heating the reactants in an aqueous solution at around 80°C, followed by work-up and purification steps. The yield is typically around 75-80%, and the use of appropriate catalysts can enhance selectivity and yield in the reaction.