γ-CF ₃ -allenamides, Fluorinated Conjugated Dienes, and 4-Trifluoromethyl Pyrrolidines: Divergent Synthesis from the Reaction of β-CF ₃ -1,3-enynamides with 2-Aminomalonates

A divergent synthesis of γ-CF₃-allenamides, fluorinated conjugated dienes, and 4-trifluoromethyl pyrrolidines via a simple base-mediated reaction of β-CF₃-1,3-enynamides with 2-aminomalonates was developed. The products depend on the type of electron-withdrawing group (EWG) on the nitrogen atoms of 2-aminomalonates and reaction conditions. γ-CF₃-allenamides were produced through the reaction of β-CF₃-1,3-enynamides with <i>N</i>-acetylated 2-aminomalonate by the combined use of acetonitrile as a solvent and K₂CO₃ as a base at room temperature. Fluorinated conjugated dienes could be obtained via the replacement of the acetyl in 2-aminomalonates with tosyl using the same solvent and base at 80 °C, whereas the <i>N</i>-substituent group switched to mesyl, furnishing 4-trifluoromethyl pyrrolidines by the combined use of toluene as solvent and DBU as a base at -10 °C. Substituents attached to the nitrogen atoms of β-CF₃-1,3-enynamides affected the reaction as well.