C([O:3][C:4]([C@@H:6]1[CH2:8][C@H:7]1[C:9]([O:11]CC)=[O:10])=[O:5])C.Cl.[Na+].[Cl-]>[OH-].[Na+]>[C@@H:7]1([C:9]([OH:11])=[O:10])[CH2:8][C@H:6]1[C:4]([OH:5])=[O:3]Diethyl carboxylate 3 (16.9 g, 19.3 mmol) was dissolved in 170 ml of 2N NaOH and heated under reflux for 1 h. The solution was stirred for additional 18 h at 22° C. The solution was cooled, adjusted to pH 3 with 2N HCl, saturated with NaCl, and finally extracted with ethyl acetate (2×100 ml). The pooled extracts were dried (Na2SO4), evaporated to dryness, and the white residue was used for the next step without further purification (8.5 g, 79%); mp 175-176° C. 1H-NMR (D2O): δ1.42 (m, 2H), 2.18 (m, 4H).
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