To a diglyme (1.1 L) solution of 5-chloro-2-hydroxybenzonitrile (the compound of Reference Example 1; 270 g, 1.8 mol) and (2S)-2-[(trityloxy)methyl]oxirane (465 g, 1.47 mol) was added potassium tert-butoxide (33 g, 0.29 mol) at room temperature, followed by stirring the reaction mixture at 105° C. for 23 hours. The reaction mixture was cooled with ice, to which toluene (2 L) and a 1N sodium hydroxide aqueous solution (1.35 L) were then added to separate an organic layer. The organic layer was washed 3 times each sequentially with the 1N sodium hydroxide aqueous solution (1.35 L) and warm water (3 L), followed by vacuum concentration. Toluene (3 L) was added to the concentrate, to dissolved it, followed by cooling and filtering the precipitated crystal to obtain 590 g of the title compound (yield: 85%).
