Sulfuric Acid → (2-[3-Cyclopentyl-2-(4-nitro-phenyl)-propionylamino]-thiazol-4-yl}-acetic acid methyl ester

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Reaction Steps

A solution of {2-[3-cyclopentyl-2-(4-nitro-phenyl)-propionylamino]-thiazol-4-yl}-acetic acid ethyl ester (prepared in Example 23, 160 mg, 0.37 mmol) in methanol (10 mL) was treated with a catalytic amount of sulfuric acid. The reaction mixture was refluxed for 68 h. The reaction was concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 75/25 hexanes/ethyl acetate) afforded {2-[3-cyclopentyl-2-(4-nitro-phenyl)-propionylamino]-thiazol-4-yl)-acetic acid methyl ester (82.3 mg, 53.3%) as a pale yellow oil: FAB-HRMS m/e calcd for C20H23N3O5S (M+H)+ 418.1436, found 418.1424.

Provenance & Evidence