Dimethyl Sulfoxide → Tert-butyl 4,4-difluoro-2-formylpyrrolidine-1-carboxylate

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Reaction Steps

To a stirred mixture of 1-(tert-butoxycarbonyl)-4,4-difluoro-2-pyrrolidinylmethanol (2.11 g, 8.89 mmol), Et3N (6.2 ml, 44.5 mmol), DMSO (6.3 ml, 88.9 mmol) in CH2Cl2 (20 ml) was added SO3-pyridine (4.25 g, 26.7 mmol). After 3 h stirring, the mixture was concentrated in vacuo and diluted with Et2O (200 ml). The resulting mixture was washed with 1 N HCl (100 ml) and brine (100 ml), dried over MgSO4, and concentrated in vacuo. The residue was chromatographed on silica gel with hexane-EtOAc (4:1) as eluent to give 1-(tert-butoxycarbonyl)-4,4-difluoro-2-pyrrolidinecarbaldehyde (1.40 g, 67%) as a yellow oil. 1H-NMR (CDCl3) δ1.45-1.52 (m, 9 H), 2.49 (m, 2 H), 3.75-3.88 (m, 2 H), 4.29-4.42 (m, 1 H), 9.54 and 9.60 (s, each, total 1 H).

Provenance & Evidence