77415-55-5

77415-72-6

77415-55-5

2,7-Dibenzyl-2,7-diazaspiro[4.4]nonane (prepared according to the method described in J. Org. Chem., 1981, 46, 2757-2764; 1.8 g, 5.9 mmol) was used as a raw material, which was dissolved in acetic acid solution (50 mL) containing 30% HBr. The reaction mixture was heated to reflux at 100 °C for 12 hours. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently concentrated to dryness under reduced pressure to afford the debenzylated product 2,7-diazaspiro[4.4]nonane dihydrobromide (1.4 g, 82% yield, based on dihydrobromide calculations) as a light brown solid. The structure of the product was confirmed by 1H NMR (400 MHz, CD3OD): δ 3.51-3.44 (m, 8H), 2.30-2.12 (m, 4H); 13C NMR (400 MHz, CDCl3): δ 53.7 (CH2), 49.9 (C), 46.3 (CH2), 35.6 (CH2).