[OH:1][CH2:2][CH:3]1[CH2:8][CH2:7][CH2:6][CH2:5][CH:4]1[CH2:9][OH:10]>[Pt].CC(C)=O>[C@H:3]12[CH2:2][O:1][C:9](=[O:10])[C@H:4]1[CH2:5][CH2:6][CH2:7][CH2:8]2There were weighed out 1,2-bis(hydroxymethyl)cyclohexane (7, meso compound) (144 mg, 1.00 mmol) and (S)-(−)-3,3,5,5-tetramethyl-4H-dinaphtho[2,1-c:1′,2′-e]-azepin-N-oxyl (3.0 mg, 1.00 mmol). Then, 2 ml of acetone was added to obtain a uniform solution. Two platinum electrodes (1.5×1.0 cm) were applied to the solution which was then subjected to an electrolytic oxidation reaction for 4 hours while being vigorously stirred at 0° C. and maintaining the current at 30 mA (quantity of electricity being 4.5 F/mol). After completion of reaction, silica gel was filtered off from the reaction mixture, extraction was effected with 5 ml of acetone and acetone was distilled off. The obtained residue was purified by silica gel column chromatography (ethyl acetate/hexane=7/1), giving (1R, 6S)-8-oxabicyclo[4.3.0]nonan-7-one (8) (cis lactone) (122 mg, yield 92%, optical purity 85%).
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