To a solution of ethyl 4-oxocyclohexanecarboxylate (13.5 g, 79 mmol) in methanol (150 mL) at 0 °C was slowly added sodium borohydride (5.3 g, 140 mmol). The reaction mixture was stirred continuously for 3 hours at room temperature. Upon completion of the reaction, the reaction was quenched by the addition of water (50 mL) followed by extraction with ethyl acetate (150 mL x 1, 50 mL x 2). The organic phases were combined, washed with water (50 mL), dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent ratio: hexane-ethyl acetate 1.5:1 to 1:1) to afford ethyl trans-4-hydroxycyclohexanecarboxylate (12 g, 88% yield, cis-trans ratio = 3:7) as a colorless transparent oil.1H NMR (300 MHz, CDCl3, cis-trans mixture) δ: 4.17-4.08 (m, 2H), 3.90 ( bs, 0.3H), 3.68-3.57 (m, 0.7H), 2.42-1.28 (m, 9H), 1.27-1.22 (m, 3H) ppm.(Hydroxyl signal was not observed.)
