Arynes fluoride-induced elimination

Direct, transition metal-free a-arylation of the secondary -keto amides (543) with arynes, generated from ortfto-silyl aryltriflates (542) by fluoride-induced elimination. 

In 1983, Kobayashi developed a convenient approach to arynes by the fluoride-induced 1,2-elimination of o-(trimethylsilyl)aryl triflates (Equation 12.6) [5]. The mild reaction conditions involved in this protocol are compahble with a variety of reagents, substrates, functionalities and even transition metal catalysts. Today, this approach is the most widely used and the most efficient method for aryne generation. 

Kobayashi and co-workers introduced 2-(trimethylsilyl)phenyl triflate as an aryne precursor subject to benzyne formation without the need of a strong base. Fluoride-induced desilylation and rapid elimination of the sulfonate provide efficient access to benzyne in acetonitrile at room temperature (eq 1). Other solvents such as THF, acetone, dichloromethane, DME, and toluene may be used, but such conditions may require heating for benzyne formation and frequently afford diminished yields. Preparation of the benzyne intermediate is even possible in protic media, albeit with decreased efficiency and limited applicability in subsequent reaction steps. ... 

Aryne Annulation. Treatment of o-(trimethylsilyl)aryl triflates with TBAT results in the formation of ben-zyne intermediates. Fluoride-induced 1,2-eliminations of o-(trimethylsilyl)aryl triflates, which are readily prepared from phenols, have been shown to provide the respective aryne products, which, at room temperature, precipitously undergo cycloaddition in the presence of Diels-Alder adducts, including, but not limited to, tethered acyclic dienes, tethered enynes (eq 15), azomethine imines (eq 16),ene carbamates, and acetamidoacry-lates (eq 17). ... 

---