Synthesis of Triazoles (I): Sequential Sonogashira Coupling and [2+3] Cycloaddition

Significance

A synthesis of isoindoline-fused triazoles using a Sonogashira coupling-[2+3] cycloaddition sequence is described. The readily available o-iodobenzyl azide, prepared from sodium azide and the corresponding benzyl bromide in high yield, when subjected to standard Sonogashira cross-coupling conditions, undergoes an in situ copper(I)-promoted [2+3] cycloaddition to furnish the triazoles in moderate to good yields. A variety of substituted acetylenes were tested showing that not only simple alkyl- and aryl-substituted acetylenes are applicable, but also structurally more complex O-protected sugar derivatives.