To a solution of 3-Isopropylamino-5-phenyl-thiophene-2-carboxylic acid methyl ester (136 mg, 0.50 mmol) in 1,2-dichloroethane (1.0 ml) was added (1R,2S,4R)-2-Acetoxy-4-methyl-cyclohexanecarboxylic acid chloride (119 mg, 0.54 mmol) dissolved in 1,2-dichloroethane (0.6 ml) followed by PPh3 (136 mg, 0.52 mmol). The resulting solution was stirred for 20 h at 90° C. and then cooled to room temperature. It was then diluted with ethyl acetate (10 ml) and a solution of saturated NaHCO3 (10 ml). The aqueous phase was separated and washed with ethyl acetate (2×10 ml) and the combined organic layers were dried (Na2SO4), filtered and concentrated. The residue was purified by flash chromatography (0% to 25% EtOAc/Hexane) to obtain 110 mg (45%) of (1R,2S,4R)-3-[Isopropyl-(2-Acetoxy-4-methyl-cyclohexanecarbonyl)-amino]-5-phenyl-thiophene-2-carboxylic acid methyl ester. NMR 1H (CDCl3, 400 MHz): 1.5:1.0 mixture of rotamers 7.73-7.70 ppm (m, 2H, Haro); 7.69-7.63 ppm (m, 1H, Haro); 7.51-7.41 ppm (m, 4H, Haro); 7.13 ppm (s, 0.6H, Haro, major rotamer); 5.79 ppm (s, 0.4H, minor rotamer); 5.21 ppm (s, 0.6H, major rotamer); 4.95-4.88 ppm (m, 1H); 3.88 ppm (s, 1.8H, major rotamer); 3.87 ppm (s, 1.2H, minor rotamer); 2.40-2.36 ppm (m, 0.6H, major rotamer); 2.11 ppm (s, 3H); 1.78-0.77 ppm (m, 16H).
