Phosphorus oxide (P4O10) → 5-Chloro-6,7-dimethoxy-3,4-dihydroisoquinolin-1(2H)-one

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Reaction Steps

To ethyl 2-chloro-3,4-dimethoxyphenethylcarbamate 3 (2 g, 6.95 mmol) in 1,1,1,3,3,3-hexamethyldisiloxane (7.39 ml, 34.8 mmol) in a 20 ml microwave tube was added phosphorous oxichloride (6.48 ml, 69.5 mmol) and phosphorus pentoxide (4.93 g, 34.8 mmol). Microwaved at 150° C. (high absorption setting) for 1 hour. Solvent removed and poured on to the ice. Neutralized with 2M sodium hydroxide and extracted with dichloromethane. Dried over magnesium sulfate and chromotagraphed eluting with 0-20% methanol:dichloromethane to give 5-chloro-6,7-dimethoxy-3,4-dihydroisoquinolin-1(2H)-one (340 mg, 1.407 mmol, 20.24% yield).) LCMS (M+H)+: 242.1

Provenance & Evidence