Heavy‐Atom Tunneling in Organic Reactions

In the past few years, numerous investigations have been reported on the role of heavy‐atom tunneling in the area of pericyclic reactions, π‐bond‐shifting, and other processes. These studies illustrate unique strategies for the experimental detection of heavy‐atom tunneling and the increased use of calculations to predict it. This Minireview focuses primarily on carbon tunneling in ground‐state processes but also highlights nitrogen tunneling and the first example of excited‐state heavy‐atom tunneling. Salient features of these reactions along with potential limitations are discussed, as well as challenges and directions for future investigation. Taking the shortcut: Examples of tunneling by second‐row atoms are increasing and the limits are being expanded. This Minireview summarizes recent examples of heavy‐atom tunneling, highlights unique approaches for its detection, and describes computational efforts toward its prediction. Common features of these reactions and future challenges are discussed.