Hydrochloric Acid → Methyl 4-oxooxolane-3-carboxylate

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Reaction Steps

To a suspension of NaH (6.66 g, 166.5 mmol) in ether (500 mL) add methyl glycolate (15.0 g, 166.5 mmol) drop wise. Stir the reaction until evolution of H2 gas ceases. Concentrate and dissolve the solid in DMSO (300 mL). Cool the reaction to 0° C. and add methyl acrylate (16.6 mL, 183.17 mmol) drop wise. Warm the reaction to room temperature and stir overnight. Acidify the reaction with 10% HCl and extract with ether (3×). Combine organic extracts and wash with brine. Dry the organic solution (Na2SO4), filter, and concentrate in vacuo. Purify by flash chromatography (250 g SiO2, 40 mL/min, 0-50% ethyl acetate/hexane for 20 minutes and then 50% ethyl acetate/hexane for 13 minutes) to yield 4-oxo-tetrahydro-furan-3-carboxylic acid methyl ester 4a (12.9 g, 89.2 mmol, 54%) as a colorless oil. 1H NMR (δ, 400 MHz, CDCl3): 4.50 (dd, 1H, J=8.4, 9.6 Hz), 4.46 (dd, 1H, J=8.4, 9.6 Hz), 4.05 (d, 1H, J=16.8 Hz), 3.79, (s, 3H), 3.97 (d, 1H, J=16.8, Hz), 3.54 (t, 1H, J=8.4 Hz). MS calcd. 144; found (EI) 144.

Provenance & Evidence