Palladium-Catalyzed Markovnikov-Selective Hydroselenation of N-Vinyl Lactams with Selenols Affording N,Se-Acetals

The highly regioselective hydroselenation of N-vinyl lactams has been revealed to successfully afford the corresponding N,Se-acetals as Markovnikov adducts. In the case of terminal N-vinyl lactams, Markovnikov-selective hydroselenation proceeds efficiently in the absence of any catalyst (or additive), owing to the acidity of the selenols. In contrast, the self-promoted hydroselenation is inefficient with internal N-vinyl lactams. In the presence of palladium diacetate (Pd(OAc)(2)), however, the desired hydroselenation of internal N-vinyl lactams proceeds efficiently to afford the corresponding N,Se-acetals.