Exploiting the reactivities of ortho-alkynyl aryl ketones: opportunities in designing catalytic annulation reactions

ortho-Alkynyl aryl ketones as highly reactive and versatile synthons have been broadly applied in organic synthesis in the past decade considering their high reactivity and structural diversity. Among numerous transformations of ortho-alkynyl aryl ketones, four common intramolecular annulative patterns based on Baldwin's rule, including 5-exo-dig/6-endo-dig oxo-cyclization and 5/6-exo-dig/6-endo-dig carbocyclization, were often employed with the help of metal catalysts, organic oxidants, visible light photocatalysis or electrocatalysis. With great developments in recent years, ortho-alkynyl aryl ketones have become one of the most effective building blocks for the construction of furan, indenone, naphthalenone, isochromene and naphthalene scaffolds. For these reasons, this review provides an overview of the chemistry established with conversions of ortho-alkynyl aryl ketones by demonstrating their general and special reactivities, introducing and discussing their mechanisms as well as their applications.