Polyfluoroalkyl derivatives of nitrogen. Part 48. The addition of N-halogenoamines (CF3)2NX to cyclohexa-1,3- and -1,4-dienes; a new synthesis of NN- bistrifluoromethylaniline

Abstract

Treatment of cyclohexa-1,3-diene with the N-halogenoamines (CF₃)₂NX (X = Cl or Br) at –78 °C gives a mixture of the 1 : 1 adducts, trans-(CF₃)₂N–[graphic omitted]H and cis- and trans-(CF₃)₂N–[graphic omitted]H₂; in contrast (CF₃)₂NI affords the former adduct exclusively. All three amines react with cyclohexa-1,4-diene under analogous conditions to yield the 1 : 1 adduct trans-(CF₃)₂N–[graphic omitted]HX only. Dehydrohalogenation of the 1,3-diene adducts (X = Cl or Br) with various bases (KOH powder, PrⁱONa, Bu^tOK) affords a mixture of 1- and 2-(NN-bistrifluoromethylamino)cyclohexa-1,3-diene. The latter diene forms a Diels–Alder adduct with trifluoronitrosomethane and the diene mixture dehydrogenates readily over a Pd–C catalyst at 180–190 °C to give NN-bistrifluoromethylaniline exclusively in high yield.