The cyanation of arylboronic acids by using acetonitrile as the “CN” source has been achieved under a Cu(cat.)/TEMPO system (TEMPO=2,2,6,6-tetramethylpiperidine N-oxide). The broad substrate scope includes a variety of electron-rich and electron-poor arylboronic acids, which react well to give the cyanated products in high to excellent yields. Mechanistic studies reveal that TEMPOCH₂CN, generated in situ, is an active cyanating reagent, and shows high reactivity for the formation of the CN⁻ moiety. Moreover, TEMPO acts as a cheap oxidant to enable the reaction to be catalytic in copper.

Both indoles and benzo[b]furans can be obtained in high yield by the reactions of 2-iodoaniline derivatives and 2-iodophenols with terminal alkynes under mild conditions, namely in the presence of cuprous iodide (10 mol%) and a base in ethanol or 1,4-dioxane. Further investigation reveals that palladium contaminants as low as 100 ppb are responsible for these successful couplings. It is worth noting that simple aliphatic substituted terminal alkynes could be tolerated to smoothly produce indole and benzo[b]furan derivatives.