Dimethylformamide → 2,3-Dihydro-8-methoxy-4H-1-benzothiopyran-4-one

Participants

Reaction Conditions

Reaction Steps

To a solution of 3-[(2-methoxyphenyl)thio]propanoic acid (5.0 g, 23.6 mmol) in dry DCM (50 mL) at 0° C. is added oxalyl chloride (6.01 g, 4.09 mL, 47.2 mmol, 2 Eq) followed by few drops of DMF. The reaction mixture is stirred at 0° C. for 30 minutes. After 30 minutes, the solvent is removed under reduced pressure. To a solution of the acid chloride in DCM (150 mL) at 0° C. is added a solution of tin (IV) chloride in DCM (26 mL, 1 M, 26.0 mmol, 1.1 Eq) and the reaction mixture is stirred for 2 h. The reaction is quenched by addition of water and the product is extracted with DCM. The organic layer is dried over MgSO4, concentrated under reduced pressure. The crude residue is purified by flash chromatography (eluent: ethyl acetate/hexane 4/6) to afford 3.2 g of the title compound as a white solid.1H NMR (DMSO-d6, 400 MHz): δ 7.59-7.57 (m, 1H), 7.18 (m, 2H), 3.84 (s, 3H), 3.24-3.21 (m, 2H), 2.84-2.81 (m, 2H). MS (ESI+): 196.0. HPLC (max plot) 89.4%; Rt 3.36 min.

Provenance & Evidence