Determine compounds A, B, and C from the following reaction sequence.

The coupling of an alkyne with an aryl halide in the presence of a palladium catalyst and triethylamine is called a Sonogashira reaction. What reactants couple to form this product?

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Predict the product of the following Sonogashira coupling reactions.

(a) <IMAGE

Predict the product of the following Sonogashira coupling reactions.

(b) <IMAGE

Suggest two coupling partners that could be used to synthesize the compounds shown making the indicated C―C bonds.

(a) <IMAGE>

The trimethylsilyl (TMS) group, used as a protecting group for alcohols, can also be used a protecting group for terminal alkynes. Show how TMS-acetylene could be used to link together two aryl halides using the Sonogashira reaction. [Hint: Deprotection of the TMS-acetylene can be done using KF in H₂O .]

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Determine the product from the following Sonogashira Reaction.