Chlorosuccinimide → 4-chloro-1-isopropyl-5-(2-methoxy-5-nitro-phenyl)-1H-pyrazole

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Reaction Steps

To a stirred, ice-cooled solution of 1-isopropyl-5-(2-methoxy-5-nitro-phenyl)-1H-pyrazole from Example 1.81, Step C (1.0 g, 3.83 mmol) in DMF (10 mL) was added NCS (0.56 g, 4.22 mmol) over a period of 10 minutes. The reaction mixture was warmed to ambient temperature and stirred at 55° C. for 6 h. The reaction mixture was cooled and poured into an ice-water mixture with vigorous stirring to form a white solid, which was filtered and washed with cold water until free of DMF. The solid was dried in vacuo to yield 4-chloro-1-isopropyl-5-(2-methoxy-5-nitro-phenyl)-1H-pyrazole (1.1 g, 97%). LCMS m/z (%)=296 M+H+, (35Cl, 100), 298 (37Cl, 28.5). 1H NMR (400 MHz, CDCl3) δ: 8.4 (dd, J1=9.09 Hz, J2=2.78 Hz, 1H), 8.19 (d, J=2.8 Hz), 7.6 (s, 1H), 7.14 (d, J=9.18 Hz, 1H), 4.10 (m, 1H), 3.94 (s, 3H), 1.49 (d, J=6.62 Hz, 3H), 1.36 (d, J=6.62 Hz, 3H).

Provenance & Evidence