Synthesis of [6,5,5]Ring-Fused Tricyclic Triazoles by Copper-Promoted Double Cyclization

Abstract

Copper(I)-mediated azide-alkyne cycloaddition was coupled with cross-coupling for the synthesis of [6,5,5] ring-fused tricyclic triazoles. Copper(I)-mediated azide-alkyne cycloaddition was investigated on 2-iodoaryl propynes or propynones. With catalytic amount of Cu(I) salts or with N-donor ligands on copper only the products of azide-alkyne cycloadditions were formed. However, with an equimolar amount of copper(I) iodide and triethylamine new [6,5,5] ring-fused tricyclic triazoles were formed by azide-alkyne cycloadditon coupled to a cross-coupling reaction.