Methyl 3-oxocyclobutanecarboxylate (3075 g, 24.0 mol, 1.0 eq.) was dissolved in 30 L of tetrahydrofuran and cooled to -78 to -60 °C. Under stirring, 20 L of tetrahydrofuran solution of lithium hydrogenated tri-tert-butoxyaluminum (36.0 mol, 1.5 eq.) was added dropwise and the reaction was kept for 4 hours. Upon completion of the reaction, the progress of the reaction was monitored by TLC. Subsequently, the reaction was quenched dropwise by addition of 6 mol/L hydrochloric acid and the pH of the reaction solution was adjusted to 5-6 at about 0 °C. The reaction mixture was diluted with 20 L of ethyl acetate and stirred for 30 min. The reaction mixture was filtered through a diatomaceous earth pad and the filter cake was washed three times with ethyl acetate. The filtrate was separated and the aqueous phase was extracted and washed with ethyl acetate. All organic phases were combined and concentrated by drying to give methyl cis-3-hydroxycyclobutanecarboxylate (2733 g, 21.0 mol) in light yellow liquid form in 88% yield and 95% purity.
