AbstractA transition metal‐free, regioselective C‐5 trifluoromethylation of 2,3‐dihydropyridin‐4(1H)‐ones (cyclic enaminones) with trimethyl(trifluoromethyl)silane (TMSCF3) was developed that proceeds under mild conditions at room temperature. This direct transformation was successful with both electron‐rich and electron‐deficient cyclic enaminones. This method bypasses substrate prefunctionalization and transition metal catalysis, and allows the convenient and direct access to a variety of medicinally important 3‐trifluoromethylpiperidine derivatives. This chemistry also represents a rare example of a direct trifluoromethylation of an internal olefinic CH bond. A radical mechanism is proposed for this reaction.magnified image
Boron–Heck Reaction of Cyclic Enaminones: Regioselective Direct Arylation via Oxidative Palladium(II) Catalysis
摘要:
An oxidative boron Heck reaction of cyclic enaminones with arylboronic acids is reported. This protocol provides a regioselective arylation it the C6 position of cyclic enaminones. When an N-carbamylated cyclic enaminone was employed, a switch to a conjugate addition reaction occurred in the presence of acid.