Synthesis
References
Based on control experiments and known features of palladium chemistry, a plausible reaction mechanism can be envisaged. Mechanistically, the active catalytic species Pd(0) is generated in situ by dimerization, to a small extent, of acetylenic compound 8. Next, coupling of 8 with iodide 7 takes place through the Sonogashira pathway, see: Sonogashira K, Tohda Y, Haghihara N.
Tetrahedron Lett. 1975;
50: 4467 ; leading to the formation of intermediate o-alkynyl azide derivative, which is then converted into products 1–4 through intramolecular [3+2] cycloaddition between azide and alkyne moieties. An alternative mechanism involving copper-assisted regioselective [3+2] cycloaddition between acetylene and azide groups of substrates 8 and 7, leading to the formation of intermediate 1,4-substituted 1,2,3-triazoles 9 (X = I), which may undergo intramolecular coupling with aryl iodide through C–H bond activation to form the products 1–4, was ruled out on the basis of control experiments
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