Dimethyl Sulfide → Methyl 2-chloro-6-formyl-benzoate

Into a solution of methyl 2-chloro-6-vinylbenzoate (6.7 g, 34 mmol) in dry DCM (100 mL) was bubbled O3 at −78° C. over a 30 minute period. Next, nitrogen gas was bubbled into the solution until the solution was colorless. Dimethylsulfane (4.3 g, 68 mmol) was added dropwise and the resulting mixture was warmed to RT and stirred for 2 hours. The reaction mixture was subsequently washed with water (30 mL) and extracted with DCM (3×100 mL). The organic layers were combined, dried over Na2SO4, and concentrated. The crude product was purified by column chromatography eluting with a gradient of EtOAc (0-90%) and PE to give the title compound (3.8 g, 56%). 1H NMR (400 MHz, CDCl3) δ ppm 9.89 (s, 1H), 7.728 (d, J=7.2 Hz, 1H), 7.606 (d, J=8.0 Hz, 1H), 7.489 (t, J=8.0 Hz, 1H), 3.95 (s, 3H).