Formic Acid → HCID 56656281, compound

Participants

Reaction Conditions

Reaction Steps

Methyl 7-[2-((Z)-3-diethylaminoprop-1-enyl)-4-fluorobenzenesulfonylamino]-4H-chromeno[3,4-d]isothiazole-6-carboxylate (Intermediate 72, 0.058 g) was dissolved in dioxane (1.5 mL) and water (0.6 mL). Lithium hydroxide monohydrate (0.018 g) was added and the resultant mixture was heated at 85° C., under nitrogen for 3 hours. The mixture was left to cool overnight. A further amount of lithium hydroxide monohydrate (0.010 g) was added and the mixture was heated at 85° C. for a further 1 hour. The mixture was cooled, diluted with DCM and acidified to pH4 with aqueous formic acid (10%), to give an emulsion. The emulsion was concentrated in vacuo to give a gum, which was triturated with a solution of 2M methanol in DCM and the solid was removed by filtration. The filtrate was concentrated in vacuo and the residue was purified by chromatography on silica, eluting with a mixture of methanol and DCM, with a gradient of 0-8%. The resultant product was dissolved in acetonitrile and water and freeze-dried overnight to give 7-[2((Z)-3-diethylaminoprop-1-enyl)-4-fluorobenzenesulfonylamino]-4H-chromeno[3,4-d]isothiazole-6-carboxylic acid (0.027 g) as a white solid.

Provenance & Evidence