Citric Acid → beta-[[(3-methoxyphenyl)thio]methyl]benzenepropanoic Acid, Ethyl Ester

Participants

Reaction Conditions

Reaction Steps

To a solution of 3-methoxy-thiophenol (1.4 g, 0.01 mol) and 2-phenylbutyro-lactone 2a (1.5 g, 0.0093 mol, (Tetrahedron 47, (8) 1525-40, 1991) in DMF (10.0 mL) were added potassium carbonate (1.4 g, 0.01 mol) and 18-crown-C (0.05 g), and the mixture was heated at 75° C. for 12 h under an atmosphere of argon. The reaction mixture was cooled, and partioned between 5% citric acid (25 mL) and ethylacetate (50 mL). The organic phase was washed with water (2×25 mL), dried dried (Na2SO4) and concentrated under reduced pressure to give a yellow syrup. This was purified by silica gel flash chromatography using 20% EtOAc in hexane. Fractions containing the desired acid as monitored by ES mass spectrometry, [m/z=303 (M+H)] were combined and concentrated. This material was dissolved in EtOH (5 mL), added 4N HCl/dioxane (5.0 mL) and stirred at room temperature for 1 h, and at 70° C. for 1 h. The resulting solution was concentrated to dryness and the residue was purified by silica gel flash chromatography using 20% EtOAc in hexane to give 1.2 g (40%) of the desired ester as a pale yellow liquid: 1H-NMR (400 Mz, CDCl3) δ 7.35-7.15 (m, 5H), 6.87 (m, m 1H), 6.85 (m, 1H), 6.70 (m, 1H), 4.02 (m, 2H), 3.77 (m, 3H), 3.18 (d, 2H, J=7.2 Hz), 2.92 (dd, 1H, J=6.4 Hz), 2.65 (dd, 1H, J=8.0 Hz), and 1.11 (t, 3H, J=6.8 Hz); ES-MS m/z 331 (M+H)+; HR-MS Calcd C19H23O3S 331.1100, found 331.1377.

Provenance & Evidence