Three-component Reaction Of Alkynes Research Articles

Rhodium-Catalyzed Three-Component Reaction of Alkynes, Arylzinc Chlorides, and Iodomethanes Producing Trisubstituted/Tetrasubstituted Alkenes with/without 1,4-Migration.

A three-component reaction of alkynes, arylzinc chlorides, and iodomethanes was found to proceed in the presence of a rhodium catalyst to give high yields of trisubstituted/tetrasubstituted alkenes. The usual arylzinc chlorides only gave trisubstituted alkenes, generated through a migratory carbozincation-cross-coupling sequence, where 1,4-Rh migration from an alkenyl carbon to an aryl carbon occurred. In contrast, 5-membered heteroarylzinc chlorides only gave the tetrasubstituted alkenes via a carborhodation-cross-coupling pathway without 1,4-migration.

Batch and Continuous-Flow Huisgen 1,3-Dipolar Cycloadditions with an Amphiphilic Resin-Supported Triazine-Based Polyethyleneamine Dendrimer Copper Catalyst

A polystyrene–poly(ethylene glycol) (PS–PEG) resin-supported triazine-based polyethyleneamine dendrimer copper catalyst (PS–PEG-TD2–CuSO4) was prepared and characterized by means of CP-MAS NMR, UV–vis/NIR, FTIR, SEM-EDX, XPS, and ICP-AES analyses. PS–PEG-TD2–CuSO4 was highly active in the Huisgen 1,3-dipolar cycloaddition of various organic azides with alkynes in water as well as the three-component reaction of alkynes, alkyl bromides, and sodium azide under batch conditions to give the corresponding triazoles in excellent yields with high recyclability of the catalyst. TEM analysis suggested that the copper nanoparticles generated in situ through reduction of PS–PEG-TD2–CuSO4 with sodium ascorbate serve as the active catalytic species. The application of PS–PEG-TD2–CuSO4 catalyst in a continuous-flow Huisgen reaction for the synthesis of 1,2,3-triazoles was also examined. The cycloaddition of organic azides with alkynes was completed within 22 s in the continuous-flow system containing PS–PEG-TD2–CuSO4 t...