Trifluoroacetic acid → 4-Methanesulfonyl-6-(piperazin-1-ylmethyl)-3,4-dihydro-2H-benzo[1,4]oxazine

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Reaction Steps

tert-Butyl 4-(4-methanesulfonyl-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethyl)piperazine-1-carboxylate (2.5 g, 6.1 mmol) was dissolved in dichloromethane (50 mL) and treated with trifluoroacetic acid (182 mmol). The resulting mixture was stirred at ambient temperature for 3 h then evaporated to dryness under reduced pressure. The residue was extracted with hot ethanol and the combined extracts evaporated to dryness under reduced pressure. Chromatography on SiO2, eluting with 0.880 ammonia/methanol/dichloromethane (1:9:90), gave the title compound (1.2 g, 63%) as an off-white solid.

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