Hydrochloric Acid → 6-[2-(4-Bromo-2-chloro-phenyl)-propionyl]-2,2,4-trimethyl-4H-benzo[1,4]oxazin-3-one

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Reaction Conditions

Reaction Steps

A mixture of 5-[2-(4-bromo-2-chloro-phenyl)-propionyl]-3-methyl-3H-benzooxazol-2-one (20 mg, Example 116 step 7) in 1N aqueous NaOH (1 ml) and dioxane (1 ml) was heated for 20 min at 100° C. in a microwave oven. Aqueous 1N HCl solution (1.2 ml) was added, followed by NaHCO3 (100 mg) and EtOAc (10 ml). Bromoisobutyryl bromide (20 mg) was added and the mixture was stirred for 1 h. Water (10 ml) was added and extracted with EtOAc. The combined organic layers were dried over Na2SO4 and then concentrated to an oil. The residue was dissolved in DMF (3 ml), and K2CO3 (100 mg) was added. The mixture was heated to 100° C. for 2 h. The mixture was purified by prep. HPLC (C18-column, solvent gradient 20-98% CH3CN in 0.1% HCOOH[aq]) to give the title compound (11 mg) as a light yellow oil. MS (m/e)=438.0 [M+H+].

Provenance & Evidence