Dimethylformamide → 2-Chloro-5-methyl-1,3-benzoxazole

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Reaction Steps

Subsequently, the 5-methyl-2-mercaptobenzoxazole (6.2 g, 38 mmol) was dissolved in thionyl chloride (36.9 mL) and 2.79 mL of DMF was added. The reaction mixture was then stirred at r.t. for 30 min. The solvent was removed under reduced pressure and to the residue was added toluene (2×60 mL) followed by evaporation each time to remove excess SOCl2 via an azetrope. The resultant crude product was dissolved in ethyl acetate (100 mL), washed with water (100 mL) and dried over Na2SO4. Evaporation of ethyl acetate gave crude 22 which was purified by silica-gel column chromatography (eluent: petroleum ether) to provide pure 2-chloro-5-methylbenzoxazole, compound 22, (3.5 g, 58%).

Provenance & Evidence