Cesium carbonate → Tert-butyl 4-(3-methoxy-4-nitrophenyl)piperazine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

4-chloro-2-(methyloxy)-1-nitrobenzene (10 g, 53.2 mmol, Aldrich), 1,1-dimethylethyl 1-piperazinecarboxylate (20 g, 107.5 mmol), cesium carbonate (35.0 g, 107.5 mmol), Pd2dba3 (5 g, 5.5 mmol), and XANTPHOS (4.62 g, 8.0 mmol) were added to degassed dioxane (100 mL) and heated to 100° C. under a water cooled reflux condenser for 12 hours. The dioxane was removed under reduced pressure and the solids were partitioned between methylene chloride (500 mL) and water (500 mL). The organic layer was dried over sodium sulfate, taken to a residue under reduced pressure, and triturated with a methylene choride/hexanes mixture (15:85) to precipitate out analytically pure 1-dimethylethyl 4-[3-(methyloxy)-4-nitrophenyl]-1-piperazinecarboxylate as a yellow solid (13.2 g, 39.2 mmol, 73% yield). 1H NMR (400 MHz, CDCl3) δ ppm 1.49 (s, 9 H), 3.33-3.42 (m, 4 H), 3.62-3.64 (m, 4 H), 3.96 (s, 3 H), 6.39 (s, 1 H), 6.44 (dd, J=9.16, 2.56 Hz, 1 H), 8.01 (d, J=9.16 Hz, 1 H).

Provenance & Evidence