Triethylamine → Tert-butyl 4-(4-cyano-3-nitrophenyl)piperazine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of a mixture of compound 17 (3 g, 13.27 mmol) and 1-boc-piperazine hydrochloride (3.53 g, 15.92 mmol) in DMF (30 mL) was added Et3N (4.4 mL, 31.8 mmol), and the mixture was heated at 70° C. for 6 h. The mixture was cooled to room temperature, extracted with ethyl acetate (100 mL), and the organic layer was washed with brine (20 mL), dried over Na2SO4 and evaporated. Trituration with diethyl ether afforded 4.27 g (97%) of compound 18 as bright yellow solid, m.p. 138-139° C.; IR (KBr) νmax. cm−1: 3042 (Ar—H), 2252 (CN), 1690 (C═O), 1610, 1520, 1412 (C═C). 1H NMR (500 MHz, DMSO-d6) δ=1.39 (s, 9H, (CH3)3C); 3.44 (br. s, 4H, 2 CH2); 7.19 (dd, 1H, J=2.6, 9.4 Hz, H-5); 7.46 (d, 1H, J=2.7 Hz, H-2); 8.17 (d, 1H, J=2.7 Hz, H-6); 13C NMR (125.7 MHz, DMSO-d6) δ=28.11 (CH3)3C), 45.92 (CH2), 46.02 (CH2), 79.56 (CH3)3C), 109.24 (C-4), 115.61 (C-2), 116.46 (CN), 119.03 (C-6), 128.09 (C-5), 135.85 (C-3), 153.30 (C-1), 154.13 (C═O). Calculated (%) for C16H20N4O4 (332.15); C: 57.82, H: 6.07, N: 16.86. found (%); C: 57.76, H: 6.11, N: 16.80.

Provenance & Evidence