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

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Reaction Steps

To a solution of sodium methoxide (5.4 M, 4.8 mL) in MeOH (20 mL) was added diethyl phosphite (3.31 g, 24 mmol) at 0° C. followed by addition of 2-formylbenzoic acid (3.0 g, 20 mmol) portion-wise over a period of 20 min. The resulting mixture was warmed up to rt and continued to stir for 2 h. Methanesulphonic acid (2.69 g, 28 mmol, 1.4 equiv.) was added to the above mixture over a period of 30 min. The reaction mixture was stirred for 30 min and concentrated to remove most of the MeOH. The residue was partitioned between DCM (100 mL) and water (50 mL). The aqueous layer was extracted DCM twice. The combined organic layer was dried over Na2SO4 and concentrated to give dimethyl 3-oxo-1,3-dihydroisobenzofuran-1-ylphosphonate (4.6 g, 90%). LRMS (M+H+) m/z 257.1.

Provenance & Evidence