Methanesulfonic Acid → 1-ethyl-3-[5-hydroxy-7-[(E)-methoxyiminomethyl]-1,3-benzothiazol-2-yl]urea

Participants

Reaction Steps

(E)-1-(5-(benzyloxy)-7-((methoxyimino)methyl)benzo[d]thiazol-2-yl)-3-ethylurea (325 mg, 0.85 mmol) was stirred in DCM (17 ml) and methanesulfonic acid (2.8 ml) was added. The reaction was allowed to stir at rt for 1 h in a round bottomed flask equipped with a drying tube. LCMS showed a mixture of product and starting material and the reaction was stirred for a further 1 h and LCMS showed no further reaction. Methanesulfonic acid (0.5 ml) was added and the reaction stirred for 18 h, diluted with DCM (30 ml) and extracted with water (2×25 ml). The DCM layer contained mainly starting material and impurities by LCMS. The aqueous portions were combined, and solid sodium hydrogen carbonate was used to adjust the pH to ˜10 and then extracted with a 1:1 mixture of DCM-Et2O. The combined organic extracts were washed with water, dried (MgSO4) and concentrated to afford a yellow solid (100 mg, 80% purity by LC-MS) (40%) which was used directly in the next step.

Provenance & Evidence