Reaction Steps
560 mg of ethyl 2-oxo-2-(8-oxo-5,6,7,8-tetrahydro-4H-cyclo hepta[b]thiophen-7-yl)acetate prepared in example 9d are solubilized in absolute ethanol (11 mL). 580 mg of 2,4-dichlorophenyl-hydrazine hydrochloride are added. The reaction mixture is heated under reflux conditions for 14 hours. The solvent is removed under vacuum and the obtained residue is purified by chromatography on silica gel by using as eluent a mixture of ligroin/ethyl acetate 9:1 volume/volume. 300 mg of ethyl 1-(2′,4′-dichlorophenyl)-1,4,5,6-tetrahydro-thieno[3′,2′:6,7]-cyclo-hepta[1,2-c]pyrazol-3-carboxylate are obtained (orange solid; yield 35%). Rf=0.20 (ligroin/ethyl acetate 9/1 volume/volume); 1H NMR (CDCl3) δ (ppm): 7.55 (d, 1H, ArH), 7.48 (d, 1H, ArH), 7.42 (dd, 1H, ArH), 7.03 (d, 1H, ArH), 6.79 (d, 1H, ArH), 4.44 (q, 2H, OCH2), 3.29 (m, 2H, CH2), 2.99 (m, 2H, CH2), 2.06 (m, 2H, CH2), 1.42 (t, 3H, CH3); 13C NMR (CDCl3) δ (ppm): 162.8, 143.2, 142.4, 137.2, 136.4, 135.3, 131.9, 130.3, 130.0, 128.1, 124.8, 124.2, 122.4, 61.0, 30.9, 26.1, 24.4, 14.5; FT-IR (film) νmax: 3092.7, 2928.9, 1712.5, 1486.6, 1446.9, 1245.6, 1190.9, 1100.3, 947.0, 713.9, 641.6, 610.6 cm−1.
