Catalyst-Free Synthesis of Trifluoromethylated Five- and Seven-Membered Nitrogen-Containing Heterocycles via Aza-Michael Addition and Lactamization of Trifluoroethylene Oxindoles

A novel protocol for the synthesis of trifluoromethylated pyrazolidiones and 1,5-benzodiazepinones was reported. In this strategy, hydrazines and 1,2-diaminobenzenes were used as binucleophiles to react with isatin-derived trifluoroethylene oxindole acrylates under catalyst-free conditions, and an aza-Michael addition/lactamization process occurred to give the corresponding products in good yields. Both <i>cis</i> and <i>trans</i> diastereoisomers of pyrazolidinones were obtained, and the possible mechanism and stereochemistry of this reaction was also discussed.