Nitrile-substituted enamide

Lithiated alkoxyallenes, nitriles, and TFA have been employed as precursors in a three-component reaction leading to highly substituted enamides 42a-d. Upon treatment with trifluoroacetic acid, these enamides could be easily cyclized to 2-trifluoromethyl-5-acetyloxazole derivatives 43a-d [47]. Two most probable pathways for oxazole formation from enamides were proposed. 

Cycloaddition. The combination of enamides with alkynes (or enol ethers) and with nitriles gives substituted pyridines and pyrimidines, respectively, as promoted by Tf20. 

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