[C:1]1(=[O:7])[O:6][CH2:5][CH2:4][CH2:3][CH2:2]1.OS(O)(=O)=O.[C:13]([O-])(O)=[O:14].[Na+]>CO>[OH:14][CH2:13][CH2:4][CH2:3][CH2:2][C:1]([O:6][CH3:5])=[O:7]To prepare 2, freshly distilled δ-valerolactone (1) (856 mg) in methanol (17 ml) was treated with concentrated H2SO4 (100 μl) and refluxed for 12 hours. The solution was cooled to −20° C., treated with NaHCO3 (80 mg), and stirred for 10 minutes. The reaction mixture was filtered and the solvent was removed in vacuum. The residue was taken up in DCM (10 ml), dried over Na2SO4, filtered, and concentrated in vacuum to give methyl 5-hydroxypentanoate (2) (Huckstep et al., Synthesis 10:881-82 (1982), which is hereby incorporated by reference in its entirety) (1071 mg, 94%) as a colorless oil, which was used directly without any further purification. 1H NMR (400 MHz, acetone-d6): δ 1.55 (2H, m), 1.68 (2H, m), 2.35 (2H, t, J=7.4 Hz), 3.57 (2H, m), 3.64 (3H, s); 13C NMR (100 MHz, acetone-d6): δ 22.2, 32.9, 34.1, 51.5, 61.9, 174.2. See FIGS. 75A-B.
Wird geladen…
