To a dry, N2 purged 50 mL round bottom flask attached with condenser was added 1-(2-Chloro-phenyl)-5-[5-(3-methanesulfonyl-phenyl)-thiophen-2-yl]-1H-pyrazole-3-carboxylic acid ethylamide (100 mg, 206 μmol), Lawesson's reagent (200 mg, 494 μmol), and anhydrous toluene (8 mL). The reaction solution was allowed to stir at reflux for 14 hrs. The reaction solution was allowed to cool to room temperature prior to addition of a 1:1 mixture of benzene and Et2O. The resulting precipitate was removed by vacuum filtration through a Buchner funnel. The filtrate was concentrated on the Rotavapor and the crude residue was chromatographed through a 12 g SiO2 column using a mobile phase gradient of 100% Hx to 50% EtOAc to afford 39 mg (38% yield) of the title compound. 1H NMR (400 MHz, CDCl3) δ 8.68 (br s, 1H), 8.02 (s, 1H), 7.83 (d, 1H), 7.72 (d, 1H), 7.48-7.70 (m, 5H), 7.42 (s, 1H), 7.22 (d, 1H), 6.83 (d, 1H), 3.87 (m, 2H), 3.07 (s, 3H), 1.36 (t, 3H). MS (ES) 502.3, 504.3 [M+H]+.
