5-(3,3-Dimethyl-but-1-ynyl)-3-[(4-methyl-cyclohex-3-enecarbonyl)-(4-oxo-cyclohexyl)-amino]-thiophene-2-carboxylic acid methyl ester (233 mg, 0.51 mmol) in THF (3 mL) and water (0.3 mL) was treated with sodium borohydride (19 mg, 0.48 mmol). After stirring for 20 min, water was added and the reaction mixture was extract twice with ethyl acetate. The combined organic layers were dried over sodium sulfate, filtered and concentrated. Flash chromatography (10% EtOAc:hexanes, 4 min, 10-70% EtOAc:hexanes, 12 min, 12 g column) afforded 130 mg (59% yield) of the desired 5-(3,3-dimethyl-but-1-ynyl)-3-[(4-hydroxy-trans-cyclohexyl)-(4-methyl-cyclohex-3-enecarbonyl)-amino]-thiophene-2-carboxylic acid methyl ester.
