Transition metal-catalyzed reactions using alkynes as precursors of carbene, vinylidene, and allenylidene complexes

Abstract

This review summarizes the recent advances in catalytic reactions involving alkylidene-, vinylidene-, and allenylidene complexes in situ generated from functionalized alkynes. Reactions of alkylidene complex intermediates are classified by their generation pathways: 1) alkyne-metathesis with carbene complexes as catalysts, 2) cyclization of π-alkyne complexes with intramolecular alkene moieties, 3) cyclization of π-alkyne complexes with intramolecular carbonyl or iminyl moieties, 4) migration in π-alkyne complexes, 5) tautomerism of metalacyclopentadiene generated from ω-diynes. Catalytic reactions via vinylidene and allenylidene complexes are presented with an emphasis on the type of reaction mechanism involved; 1) nucleophilic addition, 2) metallacycle formation ([2 + 2] cycloaddition), 3) migratory insertion of ligand moieties, 4) cycloaromatization, 5) pericyclic reaction.