15224-11-0

Step 1: To a solution of ethyl rel-(1R,2R)-2-formylcyclopropanecarboxylate (2.00 g, 13.68 mmol) in anhydrous ethanol (55.0 mL) was added sodium borohydride (0.776 g, 20.53 mmol) in one portion at room temperature and anhydrous conditions. The reaction mixture was stirred at room temperature for 5 h. Subsequently, the reaction was quenched with phosphate buffer aqueous solution (100 mL) at pH 7 and the ethanol was removed by distillation under reduced pressure. The remaining aqueous phase was decanted with dichloromethane (100 mL) followed by further extraction with dichloromethane (2 x 100 mL). The organic phases were combined and washed sequentially with phosphate buffered aqueous solution (70 mL) and saturated saline (70 mL) at pH 7. After drying with anhydrous magnesium sulfate, the product was filtered and concentrated to afford ethyl 2-(hydroxymethyl)cyclopropanecarboxylate (C-5) as a light-yellow oil (1.334 g, 68% yield), which was ready for use in the subsequent steps without further purification. Mass spectrometry analysis showed [M + 1] peak: m/e 145.

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