Methanesulfonic Acid → 1-Ethyl-3-[5-hydroxy-7-(2-pyridyl)-1,3-benzothiazol-2-yl]urea

Participants

Reaction Steps

To a stirred solution of 1-[5-benzyloxy-7-(2-pyridyl)-1,3-benzothiazol-2-yl]-3-ethyl-urea (76 g, 0.187 mol) in DCM (1.7 L) was added methane sulfonic acid (270 mL, 4.17 mol) dropwise over 30 min. The reaction mixture was then stirred at rt for 3 h. After the completion of reaction (by TLC), the reaction mass was concentrated under reduced pressure. EtOAc (1 L) was added to the residue and the solution poured carefully onto crushed ice. The pH of the solution was maintained to 8-9 by addition of saturated NaHCO3 solution followed by extraction with EtOAc (3×5 L). The combined organics were washed with water, brine, dried (anhydrous Na2SO4), filtered and concentrated under reduced pressure. The residue thus obtained was stirred in Et2O (1.0 L) for 1 h at rt then filtered to obtain the desired product (57.0 g, 97%). 1H-NMR (DMSO-d6): δ 1.08 (t, J=7.20 Hz, 3H), 3.20 (m, 2H), 6.86 (br s, 1H), 7.0 (s, 1H), 7.46 (s, 2H), 7.96 (m, 1H), 8.10 (m, 1H), 8.76 (m, 1H), 9.59 (br s, 1H) and 10.41 (br s, 1H). LCMS: 315.06 [M+H]+.

Provenance & Evidence