Orbital Crossings Activated through Electron Injection: Opening Communication between Orthogonal Orbitals in Anionic C1-C5 Cyclizations of Enediynes.

Generally, the long-range electronic communication between spatially orthogonal orbitals is inefficient and limited to field and inductive effects. In this work, we provide experimental evidence that such communication can be achieved via intramolecular electron transfer between two degenerate and mutually orthogonal frontier molecular orbitals (MOs) at the transition state. Interaction between orthogonal orbitals is amplified when the energy gap between these orbitals approaches zero, or at an "orbital crossing".