Hydrochloric Acid → rac-(1R,2R)-2-(methoxycarbonyl)cyclopropane-1-carboxylic acid

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Reaction Steps

Suspend trans-cyclopropane-1,2-dicarboxylic acid dimethylester (59.8 g, 0.378 mol) is suspended in 1.0N phosphate buffer (1.5 L, pH=7) add pig liver esterase (2.25 mL, 7500 units), and monitor NaOH consumption with a pH meter to control the reaction. After 3 h the consumption of 189 mL of 2N NaOH indicates the complete hydrolysis of the diester to the monomethylester. Acidified the clear solution by the addition of 5N HCl to a pH=1. Separate the enzyme by addition of dichloromethane (500 mL) and diatomaceous earth (25 g). Stir for 5 min, and then filter the mixture. Saturate the filtrate with NaCl, and extract with ethyl acetate (5 times). Combine the extracts, dry (Na2SO4) and evaporate to obtain 50.8 g (93%) of solid, mp 46–47° C., m/z=145 (M+H)+

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