General procedure for the synthesis of 3-hydroxycyclobutanecarboxylic acid from methyl 3-hydroxycyclobutanecarboxylate: cis-3-hydroxycyclobutanecarboxylic acid methyl ester (273.3 g, 2.1 mol, 1 eq.) was dissolved in a mixed solvent of H2O/THF (1 L/1.5 L), followed by addition of lithium hydroxide monohydrate (218.2 g, 5.2 mol, 2.5 eq.). The reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, THF was removed by distillation under reduced pressure. the pH of the reaction solution was adjusted to 4~5 with dilute hydrochloric acid, and then extracted with a chloroform/isopropanol solvent mixture in the ratio of 4:1 by volume. The organic phases were combined, dried with anhydrous sodium sulfate and concentrated under reduced pressure to give the crude product. The crude product was purified by ethyl acetate/n-heptane mixed solvent pulping to afford 3-hydroxycyclobutanecarboxylic acid (197.4 g, 1.7 mol) in off-white solid form with 81% yield and 97% purity.
