Recent progress towards transition-metal-catalyzed arylative cyclization/annulation reactions with boronic acids

Recent Progress in Arylmetalative Cyclization/Annulation of Functionalized Alkynes with Organoboranes

“…Carbo/hetero‐metalation of alkynes is an outstanding approach to access a wide range of highly substituted olefins with regio‐ and stereo selections [1–12] . After the pioneering discovery of carbo‐cupration in the early 1970s enormous attention has been paid to carbo and hetero metalation of alkynes (orthogonal activation of alkynes) which has resolved several long‐lasting problems associated with the selective synthesis of olefins through conventional methods [1] .…”

“…A few recent breakthroughs expose that a nearby coordinating group can also help the event occur in a highly selective way ( vide infra ). The kind of functional groups which can be introduced on olefin, range from halo, silyl, boryl, stanyl, thio, cyano, sulfonyl, amino, carboxyl, alkyl, alkenyl, alkynyl to aryl on both the internal and terminal alkynes [2–12] . Using the high intrinsic electron bias, heteroatom‐attached alkynes and ynones were also extensively studied for this carbo/hetero metalation [4] .…”

“…Aryl‐metalation and its associated cyclization with a tethered electrophile (arylative cyclization) provide a straightforward, powerful, and atom‐economical approach to diverse and widely useful carbo‐ and heterocycles that are employed in organic and medicinal chemistry [6–12] . In this concept, the newly formed alkenyl metal complex readily reacts with pendent electrophile through chelation.…”

“…For this aryl‐metalation, a series of common organometallic reagents based on Mg, Zn, Zr, Cu, Sn, etc., were used previously [3] . Later, the nontoxic, benchtop and stable aryl boronic acids were brought up as revolutionary substitutions for nucleophilic aryl sources through trans‐metalation [6–13] . Study on the use of companionable metal complexes with these aryl boronic acids on various substrates is a buzzing subject in current chemistry.…”

“…Immense progress has been made in discovering the compatibility of various transition‐metal catalysts (based on Pd, Rh, Ru, Ni, Co, etc.) with aryl boronic acids for arylative functionalization strategy [6–14] . In this line, some recent reviews by Youn, [7] Partyka, [8] Huang, [9] Corpas, [10] Lam, [11] Ganesh [12] and others [13] have successfully recapitulated the advancements in one specified class of reactions (metal, reagent, starting materials and mode of cyclization) or classification based on the kind of product obtained.…”