Theoretical investigation of Co(0)-catalyzed intramolecular hydroacylation of 4-pentenal.

Density functional theory (DFT) was used to investigate cobalt(0)-catalyzed intramolecular hydroacylation of 4-pentenal. The calculated results indicated the involvement of five possible reaction pathways: the formation of cyclopentanone, cyclobutanone, butylenes, cyclobutane, and cyclopropane, respectively. The former two are pathways of Co(0)-catalyzed intramolecular hydroacylation, while the latter three are pathways of decarbonylation. The formation of cyclopentanone was the most favorable channel, and the oxidative addition reaction of 4-pentenal was the rate-determining step. Hence, the dominant product predicted theoretically was cyclopentanone, which was consistent with experimental results. Solvation had a significant effect, and greatly decreased the free energies of all intermediates and transition states.