Transition-Metal-Catalyzed Functionalization of Alkynes with Organoboron Reagents: New Trends, Mechanistic Insights, and Applications

Catalytic functionalization of alkynes with organoboron reagents provides a straightforward access to stereochemically defined multisubstituted alkenes, which are structural motifs commonly found in bioactive compounds and organic materials. Recent progress has substantially broadened the scope this field on several fronts. Strategies for regioselectivity control 1,2-migratory insertion across unsymmetrical internal alkynes, as well direct products anti-insertion stereochemistry, have been devised. The alkenyl-to-aryl 1,4-metal migration upon metal recently exploited powerful cascade sequences leading complex polycyclic scaffolds, including development enantioselective processes. Elegant enantiospecific dynamic kinetic resolution methods developed accessing chiral allenes from propargylic alcohol derivatives. Mechanistic manifolds emerged based single-electron transfer (SET) that provided fresh impetus alkyne 1,2-difunctionalization complementary stereoselectivity processes relying 1,2-insertion R–M species. Herein, we discuss most recent advances transition-metal-catalyzed using reagents, categorized according type mechanistic outcome. Emphasis is placed aspects, synthetic utility, limitations, challenges future research.