Sodium Sulfite → (S)-2-Methoxycyclohexanone

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To a 1 liter 4-necked flask, (1S,2S)-2-methoxycyclohexanol (53.57 g,0.411 mol) and methylene chloride (250 ml) were placed, and subsequently, 2,2,6,6-tetramethyl-1-piperidinyloxy free radical(1.28 g, 0.008 mol), potassium bromide (1.47 g, 0.0123 mol), and 8%-sodium hydrogencarbonate solution (52 ml, 0.0494 mol) were added and cooled to 0° C. To this mixture, 3.1N sodium hypochlorite solution (254 ml, 0.787 mol) was added dropwise over a period of 6 hours while maintaining a temperature of 0° C. to 5° C. After the disappearance of the raw material (1S,2S)-2-methoxycyclohexanol was confirmed by gas chromatography, sodium sulfite (5.36 g, 0.0425 mol) was added to the mixture to perform fractionation. Distillation was then performed, and the aqueous phase was subjected to extraction with two 25 ml portions of methylene chloride. The solvent was distilled off under a reduced pressure, and further distillation was performed to obtain (2S) -2-methoxycyclohexanone (51.67 g). The yield was 95%, the boiling point and optical purity of the product were 84° C./24 mmHg and 100%e.e., respectively. Incidentally, the gas chromatography for confirming the disappearance of (1S,2S)-2-methoxycyclohexanol was performed using the following apparatus and conditions.

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