(S)-1-BOC-2-METHYL-[1,4]DIAZEPANE

949109-36-8

194032-32-1

（Steps for the synthesis of (S)-3-methyl-1,4-diazepane-1-carboxylic acid tert-butyl ester: 1. tert-Butyl (S)-3-methyl-4-((2-nitrophenyl)sulfonyl)-1,4-diazepane-1-carboxylate (2.60 kg, 6.51 mol) was dissolved in acetonitrile (20 L). 2. Potassium carbonate (1.79 kg, 13.0 mol) was added to the above solution. 3. Benzothiophenol (2.15 kg, 19.5 mol) was slowly added at a controlled internal temperature of 20 °C or lower for 6 h. After addition, the solution was dissolved in acetonitrile (20 L) at 20 °C or lower. 4. After addition, the reaction mixture was continued to be stirred at 20 °C for 18 hours. 5. The reaction was monitored by thin layer chromatography (TLC) to confirm complete consumption of the feedstock, the insoluble material was removed by filtration and the filtrate was concentrated under reduced pressure. 6. 6. The concentrated residue was dissolved in ice water and the pH was adjusted to 3 with 2N hydrochloric acid, followed by washing with ethyl acetate. 7. The aqueous layer was alkalized to pH 9 with potassium carbonate and extracted with ethyl acetate. 8. The organic layers were combined, dried with magnesium sulfate, filtered and concentrated under reduced pressure to give a yellow oily target product (1.20 kg, 85.7% yield). 9. The chemical purity of the product was 97.5% by gas chromatography analysis. 10. The product was converted to a methylsilyl chloride derivative and the optical purity was determined to be 99.9% ee. 11. The overall yield from (S)-(+)-2-amino-1-propanol to tert-butyl (S)-3-methyl-1,4-diazepane-1-carboxylate was 45.2%. 12. The structure of the product was confirmed by 1H-NMR (DMSO-d6, 100 °C), δ: 0.94 (d, J = 6.3 Hz, 3H), 1.40 (s, 9H), 1.53-1.63 (m, 1H), 1.69-1.78 (m, 1H), 2.42-2.49 (m, 1H), 2.60-2.68 (m, 1H). 2.70-2.79 (m, 1H), 2.97 (ddd, J = 14.0, 4.6, 4.6 Hz, 1H), 3.17 (ddd, J = 14.0, 7.7, 5.8 Hz, 1H), 3.54 (ddd, J = 14.0, 6.3, 5.8 Hz, 1H), 3.60 (ddd, J = 14.0, 4.6 Hz, 1H) .