3-Oxo-azetidine-1-carboxylic acid tert-butyl ester → Tert-butyl 3,3-difluoro-[1,3'-biazetidine]-1'-carboxylate

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), 3,3-difluoroazetidine hydrochloride (0.364 g, 2.80 mmol) and 4 Å molecular sieves (2.43 g) in DCE (10 mL). The reaction mixture was stirred for 3 h at room temperature. Sodium triacetoxyborohydride (0.99 g, 4.67 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, MeOH:DCM, gradient 0:100 to 10:90) to give the title compound as a colourless oil (0.33 g, 57%). 1H NMR (300 MHz, CDCl3): δ 4.02-3.69 (m, 4 H), 3.65 (t, J=12.15 Hz, 4 H), 3.55-3.48 (m, 1 H), 1.43 (s, 9 H).

Provenance & Evidence