Pyrrolidine → 1-Azetidinecarboxylic acid, 3-(1-pyrrolidinylcarbonyl)-, 1,1-dimethylethyl ester

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Reaction Steps

Pyrrolidine (271 μL, 5.50 mmol) was added to a solution of azetidine-1,3-dicarboxylic acid mono-tert-butyl ester (1.0 g, 4.97 mmol), HATU (2.09 g, 5.50 mmol) and DIPEA (2.18 mL, 12.52 mmol) in DMF (100 mL) and the resulting mixture stirred at ambient temperature for 1 h, then concentrated in vacuo. The resulting oil was partitioned between EtOAc and water. The organic layer was separated, washed with water and brine, then dried (MgSO4) and concentrated in vacuo to give 3-(pyrrolidine-1-carbonyl)azetidine-1-carboxylic acid tert-butyl ester as a colourless oil. TFA (3 mL) was added to a solution of 3-(pyrrolidine-1-carbonyl)-azetidine-1-carboxylic acid tert-butyl ester in DCM (15 mL) and the mixture stirred at ambient temperature for 1 h, then loaded onto an Isolute® SCX-2 cartridge (25 g). The cartridge was then washed with methanol and the desired product was subsequently eluted using 2 M NH3 in MeOH. The product was collected and concentrated in vacuo to afford the title compound as a colourless oil (550 mg, 72%). 1H NMR (CD3OD, 400 MHz) δ 3.93-3.65 (m, 5 H); 3.43-3.28 (m, 4 H) and 2.00-1.81 (m, 4 H).

Provenance & Evidence