2,4-Dioxo-1,3,8-triazaspiro[4.5]decane-8-carboxylic acid tert-butyl ester1-t-Boc-piperidine-4-spiro-5'-hydantointert-Butyl 2,4-Dioxo-1,3,8-triazaspiro[4.5]decane-8-carboxylate2,4-Dioxo-1,3,8-triazaspiro[4.5]decane-8-carboxylic Acid 1,1-Dimethylethyl Estertert-butyl 2,4-dioxo-1,3,8-triazaspiro[4.5]decane-8-carboxylate