p-Toluenesulfonic acid monohydrate → 4,5-dibromo-N-(3-oxopropyl)-1H-pyrrole-2-carboxamide

Participants

Reaction Steps

A mixture of 11 (5.0 g, 13.6 mmol) and p-toluenesulfonic acid monohydrate (1.3 g, 6.84 mmol) in 80 mL of acetone/water (1:1) was refluxed for 12 h. After cooling, the reaction mixture was extracted with CH2Cl2 (3×100 mL). The combined organic extracts were dried (MgSO4) and concentrated under reduced pressure. The resulting solid was recrystallized from acetone/CH2Cl2 to afford 12 (4.0 g, 91%) as a colorless solid: mp 160-163° C.; 1H NMR (CD3COCD3) d 2.73 (td, 2H, J=6.5, 1.5), 3.63 (q, 2H, J=6.5 ), 6.85 (d, 1H, J=2.9), 7.63 (br, 1H), 9.75 (t, 1H, J=1.5), 11.73 (br, 1H); 13C NMR (CD3COCD3) d 33.9 (e), 44.3 (e), 99.5 (e), 105.6 (e), 113.3 (o), 128.8 (e), 160.3 (e), 201.6 (o); IR (nujol) 3212, 1715, 1610, 1561 cm−1; MS, m/z (relative intensity) 327 (M++5, 50), 325 (M++3, 100), 323 (M++1, 50), 247 (25), 226 (22), 171 (20), 127 (19); Anal. Calcd for C8H8N2O2Br2: C, 29.66; H, 2.49; N, 8.65; Found: C, 29.49; H, 2.57; N, 8.53.

Provenance & Evidence