tert-butyl (1S,4S)-2,5-diazabicyclo[2.2.2]octane-2-carboxylate;hydrochloride

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of (S,S)-2,5-diaza-bicyclo[2.2.2]octane-2-carboxylic acid tert-butyl ester hydrochloride (645 mg, 2.59 mmol) in DCM (26 mL) was added acetic anhydride (490 μL, 5.19 mmol) and triethylamine (1.08 mL, 7.77 mmol) and the mixture was stirred (rt, 16 h). The reaction mixture was washed with water (3×8 mL) and brine (1×8 mL). The organic layer was dried, filtered and concentrated in vacuo to provide (S,S)-5-acetyl-2,5-diaza-bicyclo[2.2.2]octane-2-carboxylic acid tert-butyl ester (658 mg, 100%). This intermediate was dissolved in DCM (3.5 mL), treated with HCl (4 M in dioxane, 3.5 mL) and stirred (rt, 16 h). The dispersion was concentrated in vacuo to provide the title compound as a beige powder (494 mg, 100%). MS (ESI): mass calcd. for C8H14N2O, 154.11; m/z found, 155.2 [M+H]+. 1H NMR (500 MHz, MeOD): 4.71 (s, 0.5H), 4.25 (s, 0.5H), 3.97 (dt, J=12.1, 2.8, 0.5H), 3.87 (d, J=2.6, 1H), 3.84-3.73 (m, 1H), 3.68 (m, 1H), 3.64 (dd, J=13.8, 1.6, 0.5H), 3.54 (m, 0.5H), 3.45 (m, 1.5H), 2.12 (m, 4.5H), 2.06-1.91 (m, 2.5H). The reaction mixture was washed with water (3×8 mL) and brine (1×8 mL) The organic layer was dried filtered concentrated in vacuo