Synthesis
The general procedure for the synthesis of tert-butyl (S)-3-aminoazepane-1-carboxylate from tert-butyl N-succinimidocarbonate and (S)-azepan-3-amine was as follows: (S)-azepan-3-ylamine (5 g, 43.8 mmol) was dissolved in 100 mL of anhydrous dichloromethane and cooled to -78 °C with magnetic stirring. In another flask, N-tert-butoxycarbonyloxy sulfonamidine (Boc-OSu, 9.7 g, 45 mmol) was dissolved in 50 mL of anhydrous dichloromethane. The succinimide solution was slowly added to the stirring amine solution over 10-15 minutes, keeping the reaction mixture at -78 °C. After addition, the reaction mixture was allowed to gradually warm to room temperature and stirring was continued for 4 hours or the completion of the reaction was confirmed by thin layer chromatography (TLC, ninhydrin color development; Rf 0.3; unfolding reagent ratio of 0.1:1:10 ammonia, methanol and dichloromethane). The reaction mixture was washed with 50 mL of water, and the aqueous layer was adjusted to pH >13 by addition of 6N sodium hydroxide and subsequently extracted with dichloromethane (3 × 100 mL). The organic layer was dried over anhydrous sodium carbonate, filtered and concentrated in vacuum to give pure tert-butyl (S)-3-aminoazepane-1-carboxylate as a viscous oil (5.1 g, 54% yield).
References
[1] Patent: WO2005/16909, 2005, A1. Location in patent: Page/Page column 68
[2] Patent: WO2005/66163, 2005, A2. Location in patent: Page/Page column 55-26