Fluorine and Perfluoroalkyl Groups into Five-Membered Heterocycles via Cyclocondensation Reactions

Introduction of Fluorine and Perfluoroalkyl Groups into Five-Membered Heterocycles via Cyclocondensation Reactions 

The anion formed on nucleophilic attack of the hydrazine stabilizes by fluoride and subsequent HF elimination to give an o ,/3-unsaturated hydrazone, which undergoes an electrocyclic ring closure with HF elimination to yield 5-fluoro-4-trifluoromethylpyrazoles. The single fluorine bonded to C(5) can be exchanged by a wide variety of nucleophiles (88S194 90BAU2338). 

Aromatic compounds susceptible to nucleophilic substitution reactions having substituents with an electrophilic center adjacent to the position of nucleophilic attack, e.g., Af,A(-dimethyl-2,4-bis(trifluoroacetyl)-l-naphthylamine, also are (1,3 ee) building blocks. They react with 

---