Reaktion #308318

Reaktionsgleichung

5-bromo-2-chloro-1-(4-methoxycarbonyl-5-oxazolylmethyl)benzene

→

1-(3-amino-2-oxopropyl)-5-bromo-2-chlorobenzene•hydrochloride

Lösungsmittel

hydrochloric acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe solvent was evaporated under reduced pressure
2. 2
   workup.DISSOLUTIONthe residue was dissolved in methanol
3. 3
   workup.ADDITIONtreated with carbon powder
4. 4
   FiltrationThe carbon powder was filtered off
5. 5
   Sonstigethe filtrate was evaporated under reduced pressure

Vorschrift

5-Bromo-2-chlorophenylacetic acid (2.0 g) obtained in Reference Example 125-(3) was dissolved in dichloromethane (40 ml), and thereto were added oxalyl chloride (0.77 ml) and N,N-dimethylformamide (one drop) at 0° C. The mixture was stirred at room temperature overnight. The solvent was evaporated under reduced pressure to give 5-bromo-2-chlorophenylacetyl chloride, which was used in the subsequent step without further purification. (2) A solution of potassium t-butoxide (1.35 g) in tetrahydrofuran (20 ml) was cooled to 0° C., and thereto was added methyl isocyanoacetate (1.33 ml). Then, a solution of the above 5-bromo-2-chlorophenylacetyl chloride in tetrahydrofuran (20 ml) was added thereto, and the mixture was stirred at 0° C. for 2 hours, and then at room temperature overnight. The mixture was cooled again to 0° C. 10% aqueous citric acid solution was added thereto, and the mixture was extracted with ethyl acetate. The extract was washed with water and brine, and dried over sodium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography (hexane:ethyl acetate=3:1) to give 5-bromo-2-chloro-1-(4-methoxycarbonyl-5-oxazolylmethyl)benzene (1.12 g) as a yellow solid. APCI-Mass m/Z 330/332 (M+H). (3) The above 5-bromo-2-chloro-1-(4-methoxycarbonyl-5-oxazolylmethyl)benzene (1.37 g) was heated under reflux in 6N aqueous hydrochloric acid solution (20 ml) overnight. The solvent was evaporated under reduced pressure, and the residue was dissolved in methanol, and treated with carbon powder. The carbon powder was filtered off, and the filtrate was evaporated under reduced pressure to give crude 1-(3-amino-2-oxopropyl)-5-bromo-2-chlorobenzene•hydrochloride (1.73 g) as a pale brown solid, which was used in the subsequent step without further purification. APCI-Mass m/Z 262/264 (M+H). (4) A mixed solution of the above 1-(3-amino-2-oxopropyl)-5-bromo-2-chlorobenzene•hydrochloride (1.70 g) in ethyl acetate (30 ml)-water (15 ml) was cooled to 0° C. Added thereto were benzoyl chloride (0.99 ml) and sodium hydrogen carbonate (2.39 g), and the mixture was stirred at the same temperature for 3 hours. The organic layer was washed with brine, and dried over sodium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by silica gel column chromatography (chloroform:ethyl acetate=95:5) to give 1-(3-benzoylamino-2-oxopropyl)-5-bromo-2-chlorobenzene (710 mg) as a colorless solid. APCI-Mass m/Z 366/368 (M+H). (5) To a solution of the above 1-(3-benzoylamino-2-oxopropyl)-5-bromo-2-chlorobenzene (710 mg) in toluene (20 ml) was added Lawesson reagent (2.35 g), and the mixture was heated under reflux for 2 hours. The reaction mixture was cooled, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=90:10) to give the desired 5-bromo-2-chloro-1-(2-phenyl-5-thiazolylmethyl)benzene (512 mg) as a colorless solid. APCI-Mass m/Z 364/366 (M+H).

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