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A mixture of 3,3-difluoropyrrolidine hydrochloride (200 mg, 1.17 mmol), 3-oxoazetidine-1-carboxylic acid tert-butyl ester (284 mg, 1.99 mmol) and triethylamine (295 μL, 221 mg, 2.18 mmol) in DCE (10 mL) was stirred at room temperature for 1 h before the addition of sodium triacetoxyborohydride (745 mg, 3.52 mmol). The resulting mixture was stirred for 72 h then diluted with DCM and washed with H2O. The organic phase was dried (Na2SO4) and concentrated in vacuo. The resulting residue was purified by column chromatography (Si—PCC, EtOAc:cyclohexane, 0-50%) affording 3-(3,3-Difluoropyrrolidin-1-yl)azetidine-1-carboxylic acid tert-butyl ester as a colourless oil (193 mg, 63%). 1H NMR (CDCl3, 300 MHz): δ 3.95 (m, 2 H), 3.82 (dd, J=8.9, 4.9 Hz, 2 H), 3.32 (m, 1 H), 2.91 (m, 2 H), 2.82-2.63 (m, 2 H), 2.33-2.32 (m, 2 H) and 1.43 (s, 9 H).

1. washwashed with H2O
2. dry with materialThe organic phase was dried (Na2SO4)
3. concentrationconcentrated in vacuo
4. customThe resulting residue was purified by column chromatography (Si—PCC, EtOAc:cyclohexane, 0-50%)