Nickel-Catalyzed Arylative Cyclizations of Alkyne- and Allene-Tethered Electrophiles using Arylboron Reagents.

The use of arylboron reagents in metal-catalyzed domino addition-cyclization reactions is a well-established strategy for the preparation of diverse, highly functionalized carbo- and heterocyclic products. Although rhodium- and palladium-based catalysts have been commonly used for these reactions, more recent work has demonstrated nickel catalysis is also highly effective, in many cases offering unique reactivity and access to products that might otherwise not be readily available. This review gives an overview of nickel-catalyzed arylative cyclizations of alkyne- and allene-tethered electrophiles using arylboron reagents. The scope of the reactions is discussed in detail, and general mechanistic concepts underpinning the processes are described.