Regioselectivity control in the metal-catalyzed functionalization of gamma-allenols, part 2: Theoretical study.

The gold-, palladium- and lanthanum-catalyzed oxycyclization reactions of azetidin-2-one-tethered gamma-allenol derivatives to a variety of fused enantiopure tetrahydrofurans, dihydropyrans, and tetrahydrooxepines have been developed experimentally (Part 1, accompanying paper). The mechanisms of these regiocontrolled metal-catalyzed heterocyclization reactions have now been computationally explored at the DFT level (Part 2). The energies of the reaction intermediates and transition states for different possible pathways have been calculated in various model systems very close to the real system. Additionally, we selected the La[N(SiH(3))(2)](3) complex to simulate the lanthanide amide precatalyst species. The agreement of theoretically predicted and experimentally observed selectivities is very good in all cases.