Oxalyl chloride → 5-[2-(4-Bromo-2-chloro-phenyl)-acetyl]-3-methyl-3H-benzooxazol-2-one

Participants

Reaction Steps

To a suspension of 3-methyl-2-oxo-2,3-dihydro-benzooxazole-5-carboxylic acid (2.20 g) in CH2Cl2 (30 mL) were added five drops of DMF and oxalylchloride (1.57 mL). The mixture was stirred at room temperature for 1.5 hours and was then concentrated to dryness. 1,2-Dimethoxyethane (150 mL) was added and the solvent was evaporated again to give the crude acid chloride (3-methyl-2-oxo-2,3-dihydro-benzooxazole-5-carbonyl chloride). To a suspension of zinc powder (1.49 g) in 1,2-dimethoxyethane (15 mL) was added tetrakis(triphenylphosphine) palladium(0) (132 mg). A suspension of the acid chloride in 1,2-dimethoxyethane (20 mL) was added. The mixture was cooled in an ice bath and a solution of 4-bromo-1-bromomethyl-2-chloro-benzene (3.25 g, [CAS Reg. No. 89720-77-4]) in 1,2-dimethoxyethane (15 mL) was slowly added over a period of 30 minutes. The mixture was stirred for 10 minutes at 0° C. and then for 2 hours at r.t. The reaction mixture was poured into ice and basified with sat. NaHCO3. The aqueous phase was then extracted two times with ethyl acetate and the organic layers were washed with brine, dried over Na2SO4, filtered and the solvent was evaporated. Ethyl acetate (50 mL) was added to the resulting precipitate and the suspension was stirred for 30 minutes at r.t. The solid was filtered off and dried in vacuo. The title compound was obtained as a light yellow solid (1.95 g, 40%). MS (neg. ion, m/e)=378.0 [(M−H)−].

Provenance & Evidence