Trifluoroacetic acid → 6-bromo-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-one

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Reaction Steps

In another exemplary reaction sequence shown in Reaction Scheme 15, 4-bromophenol is reacted with acetyl chloride (AcCl) to provide the corresponding ester, and the ester made to undergo a Fries rearrangement under Friedel Crafts conditions to provide 2-acetyl-4-bromophenol. 2-Acetyl-4-bromophenol is reacted with acetone in the presence of piperidine and trifluoroacetic acid (TFA) to give 6-bromo-2,2-dimethyl-chroman-4-one. The latter compound is reacted with the Grignard reagent of the formula R1MgX and then with acid to provide the 6-bromo-2,2-dimethyl-chromene derivative of Formula 17.

Provenance & Evidence