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(S)-2-Amino-2-cyclopropylacetic acid (10.0 g, 86.9 mmol) was slowly added to a solution of anhydrous methanol (750 mL) containing thionyl chloride (7.6 mL, 104 mmol) at 0 °C. The reaction mixture was gradually warmed to room temperature and subsequently heated to reflux for 4 hours. Upon completion of the reaction, the mixture was cooled to room temperature and concentrated under reduced pressure to give the crude product. The crude product was washed with acetone to yield 8.94 g of L-cyclopropylglycine methyl ester hydrochloride as a white solid. The yield was 62% and the mass spectrum (MS) showed a molecular ion peak of 130 (M+H+) and a melting point of 134.0-135.9 °C.

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