Step (ii): preparation of tert-butyl 3-aminopyrrolidine-1-carboxylate (Formula 49)
To a stirred solution of tert-butyl 3-hydroxypyrrolidine-1-carboxylate (Formula 48, 1.15 g, 4.16 mmol) in methanol (16.6 mL) was added 10% palladium/carbon catalyst (345 mg). The reaction mixture was stirred for 16 hours under a hydrogen atmosphere (hydrogen pressure applied via a double-layer balloon). 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 fast column chromatography to afford the target compound tert-butyl 3-aminopyrrolidine-1-carboxylate (Formula 49, 640 mg) in 82% yield.
1H-NMR (CDCl3): δ 3.65-3.45 (m, 3H), 3.45-3.33 (m, 1H), 3.20-3.0 (m, 1H), 2.12-2.02 (m, 1H), 1.80-1.65 (m, 1H), 1.46 (s, 9H).
Mass spectrum (m/z): 187 [M+H]+.
