169206-67-1

169206-66-0

169206-67-1

General procedure for the synthesis of tert-butyl 3-oxo-2,8-diazaspiro[4,5]decane-8-carboxylate from tert-butyl 4-(2-methoxy-2-oxoethyl)-4-(nitromethyl)piperidine-1-carboxylate: To a tert-butyl 4-(2-methoxy-2-oxoethyl)-4-(nitromethyl)piperidine-1-carboxylate (1.0 g, 3.2 mmol) ethanol ( 10 mL) solution was added to Raney Ni (1 g). The reaction mixture was stirred under hydrogen atmosphere at 1 atmosphere overnight. Upon completion of the reaction, the mixture was filtered through a diatomaceous earth pad to remove the catalyst and the filtrate was concentrated under reduced pressure. The crude product was purified by silica gel column chromatography using a dichloromethane solution of 10% methanol as eluent to afford the target product tert-butyl 3-oxo-2,8-diazaspiro[4,5]decane-8-carboxylate (694 mg, 86% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CD3OD): δ 3.54-3.48 (m, 2H), 3.37-3.32 (m, 2H), 3.23 (s, 2H), 2.26 (s, 2H), 1.62-1.59 (m, 4H), 1.45 (s, 9H).