Oxalyl chloride → 7-Methylchroman-4-one

Participants

Reaction Steps

A stirred solution of 5.0 grams (0.028 mole) of 3-(3-methylphenoxy)propanoic acid (i) and 5.3 grams (0.042 mole) of oxalyl chloride in 100 mL of methylene chloride was cooled to −5° C. and a few drops of DMF was added. Upon completion of addition, the reaction mixture was allowed to warm to ambient temperature where it stirred for about two hours. After this time, the reaction mixture was concentrated under reduced pressure to a residue: which was 3-(3-methylphenoxy)propanoic acid chloride. The acid chloride was stored under a nitrogen atmosphere for about 18 hours, and then it was dissolved in 50 mL of methylene chloride. The stirred solution was cooled to −4° C. and 4.1 grams (0.031 mole) of aluminum chloride was added portionwise while maintaining the reaction mixture temperature at 5° C. or less. Upon completion of addition, the reaction mixture was maintained at 5° C. for about three hours. After this time, the reaction mixture was poured into ice and extracted with three 100 mL portions of methylene chloride. The combined extracts were washed with two 50 mL portions of water and dried with sodium sulfate. The mixture was filtered, and the filtrate was concentrated under reduced pressure to a residue. The residue was purified by column chromatography on silica gel using mixtures of ethyl acetate and hexane as an eluant. The appropriate fractions of eluate were combined and concentrated under reduced pressure, yielding 3.5 grams of subject compound. The NMR spectrum was consistent with the proposed structure.

Provenance & Evidence