Radical Cycloaromatization of Systems Containing (Z)-3-hexene-1,5-diynes and (Z)-1,2,4-heptatrien-6-ynes and Related Heteroatomic Blocks

The discovery of naturally occurring enediynes in the late 1980s stimulated activity in various aspects of their use in chemistry and biology. Most of these studies relate to various reaction parameters that control the Masamune–Bergman cyclization, a process leading to the formation of diradical aromatic 1,4‐didehydrobenzene systems from (Z)‐3‐hexene‐1,5‐diynes. The cycloaromatization of enediynes is a real and promising way of forming aromatic systems. The Bergman cyclization of symmetric enediynes involves the rearrangement of (Z)‐3‐hexene‐1,5‐diynes into 1,4‐didehydrobenzoid diradicals. Considerable attention has been paid to nonclassical thermal cyclization of enediynes leading to high‐aromatic π‐conjugated molecules. These reactions include cyclization promoted by organometallic compounds, radicals, electrophiles, and nucleophiles. The mechanisms of action of the enediyne systems and their design have been studied since the time of their discovery, but along with these studies other mechanisms have been explored, including reactions of heteroatomic systems.