Methanesulfonic Acid → Dimethyl (3-oxo-1,3-dihydro-2-benzofuran-1-yl)phosphonate

Participants

Reaction Steps

Dimethyl phosphite (100 g, 0.909 mol) was added dropwise at 0° C. under nitrogen to a stirred solution of sodium methoxide [from sodium (20.9 g, 0.909 gatom)] in methanol (730 ml), the mixture was stirred for 5 minutes, and 2-carboxybenzaldehyde (95.45 g, 0.64 mol) was added in portions. The stirred mixture was allowed to warm to ambient temperature, then it was stirred for 30 minutes and cooled in ice. Methanesulfonic acid (96 g, 1 mol) was added in portions at 5–10° C., then the solvent was removed in vacuo. The residue was partitioned between dichloromethane (1800 ml) and water (450 ml), and the organic layer was separated, washed with water (2×450 ml) and dried (MgSO4) The solvent was removed in vacuo, the residue was triturated with ether (150 ml), and the resulting solid was collected by filtration, washed with ether (30 ml) and dried in vacuo to give dimethyl 3-oxo-1,3-dihydroisobenzofuran-1-ylphosphonate (139.94 g) as a white crystalline solid, m.pt 95–96.5° C.; 250 MHz 1H-nmr (d6-DMSO) δ (ppm): 3.65 (d, 3H) (—OCH3), 3.85 (d, 3H) (—OCH3), 6.4 (d, 1H) (—CH—P), 7.75 (m, 2H) (2×ArH), 7.85–8.05 (m, 2H) (2×ArH); m/z (M+H)+. 243, 100% purity.

Provenance & Evidence