Mission impossible: 5-membered heteroarynes

Courtney Roberts doesn't like being told what is and isn't possible. Heteroaromatic rings with five sides and a triple bond are so strained that they were thought to be impossible to make. But where others saw an impossibility, Roberts saw an opportunity. Now, she and her group at the University of Minnesota report that they've made 7-aza-2,3-indolynes by using nickel to stabilize the triple bond ( Science 2024, DOI: 10.1126/science.adi1606 ). It took a few years and a lot of work, but "we gave it the faith and the belief that we were going to get there in the end," says Roberts. The key to creating the elusive indolyne is back-donation of electrons from the nickel to the aryne, which makes the triple bond longer and more stable than if it wasn't supported by a metal. "We had a burden of proof on us," says PhD student and first author