Facile Synthesis of Stop-Sign Ene

Significance

Cyclooctatetraenes (COTs) have found application in a variety of fields, materials science, catalysis, and bio-active products to name a few. Previous syntheses of COTs involved Ni(0)-catalyzed cyclization of acetylenes or simple terminal alkynes; however, despite improvements, high yields and regioselectivity have remained elusive. Wender et al. demonstrate an efficient regioselective synthesis of COTs that is tolerant of a variety of functional groups (nitriles, protected amines, etc.) and peripheral ring sizes. Further, control over [2+2+2+2] (2) and [2+2+2] (3) cycloadditions can be achieved through high catalyst loading or slow addition of diyne. These data support a mechanism of metallacycle dimerization.