Bromine triphenylphosphonium bromide

Several 6-substituted pyran-2-ones have been synthesized from dehydroacetic acid (49) by bromination and conversion of the bromo-methyl group into the triphenylphosphonium bromide, and by bromination of the methyl ether (50).59 Further examples of the use of pyran-2-ones as dienes in the Diels-Alder reaction have been reported.60 61... 

Acetyl-5-bromothiophen reacted with triphenylphosphine in the absence of solvent, at 200 °C, to give (5-acetyl-2-thienyl)triphenylphosphonium bromide. Competing reaction at the oxygen of the acetyl group leads to the formation of appreciable amounts of triphenylphosphine oxide. The acetyl group underwent conventional reactions e.g., bromination of the side-chain and condensation with p-dimethylaminobenzaldehyde. ... 

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