3-Oxo-azetidine-1-carboxylic acid tert-butyl ester → 1-Azetidinecarboxylic acid, 3-[(3S)-3-fluoro-1-pyrrolidinyl]-, 1,1-dimethylethyl ester

Participants

Reaction Steps

A 25 mL round-bottomed flask was charged with a solution of 3-oxoazetidine-1-carboxylic acid tert-butyl ester (0.4 g, 2.34 mmol), (S)-3-fluoropyrrolidine hydrochloride (0.35 g, 2.8 mmol) and 4 Å molecular sieves (2.43 g) in DCE (10 mL). The reaction mixture was stirred for 2.5 h at room temperature. Sodium triacetoxyborohydride (0.99 g, 4.68 mmol) was added and the reaction mixture was stirred for 18 h at room temperature. The suspension was filtered through Celite and the filtrate was concentrated in vacuo. The residue was purified by flash chromatography (Si—PPC, EtOAc: cyclohexane, gradient 30:70 to 100:0) to give 3-((S)-3-Fluoropyrrolidin-1-yl)azetidine-1-carboxylic acid tert-butyl ester as a colourless oil (0.342 g, 60%). 1H NMR (300 MHz, CDCl3): δ 5.34-5.10 (m, 1 H), 4.01-3.93 (m, 2 H), 3.91-3.81 (m, 2 H), 3.41-3.31 (m, 1 H), 2.94-2.67 (m, 3 H), 2.56-2.46 (m, 1 H), 2.24-2.06 (m, 2 H), 1.43 (s, 9 H).

Provenance & Evidence