2,4-Difluorobenzoic acid → t-Butyl 4-(2,4-difluorobenzoyl)piperazine-1-carboxylate

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Reaction Steps

To a solution of 3.0 g (19 mmol) of 2,4-difluorobenzoic acid and 4 mL of DIEA (1.2 equiv.) in 40 mL of dry DCM is added 3.08 g (1.2 equiv) of HOBt and 4.2 g (22.55 mmol) of t-butyl piperazine-1-carboxylate, and the mixture was stirred at RT for 30 min. 4.4 g (11 equiv.) of EDCl are added and the reaction mixture is stirred overnight at RT. Water is added and the resulting mixture is extracted with DCM. The organic layer is dried over anhydrous MgSO4, filtered and concentrated in vacuo to obtain t-butyl 4-(2,4-difluorobenzoyi)piperazine-1-carboxylate as a yellow oil: 1H NMR (CDCl3, 400 MHz) δ 1.47 (s, 9H), 3.30 (m, 2H), 3.41 (m, 2H), 3.53 (m, 2H), 3.76 (m, 2H), 6.86 (dt, 1H, J=8.8 Hz and 0.8 Hz), 6.97 (dt, 1H, J=8.8 Hz and 0.8 Hz), 7.41 (dd, 1H, J=14.4 Hz and 7.2 Hz).

Provenance & Evidence