Overview of 6π 1,5‐Electrocyclization over the Past 40 Years

Comprehensive Summary As an important part of pericyclic reaction, 6π 1,5‐electrocyclization plays an important role in organic synthesis and chemical theory. Many types of five‐membered rings could be constructed via 1,5‐electrocyclization with high atom economy. Some elegant works have been reported in this field in the past few decades. However, it still needs a lot of effort in further advancements of 1,5‐electrocyclization. This review summarized the development of 1,5‐electrocyclization relying on stepwise, stoichiometric, or catalytic approaches. The 1,5‐electrocyclization reaction will be divided into three categories: aza 1,5‐electrocyclization, all‐carbon 1,5‐electrocyclization and other heteroatoms (O, P, S) involved 1,5‐electrocyclization, and related mechanistic studies will also be involved in this review.