Click chemistry toolbox expanded with 'forbidden' C–C bond forming reaction

A newly reported copper(I)-catalysed allene–ketone addition (CuAKA) offers something rare: a click reaction that forms a robust yet reversible carbon–carbon bond under biologically relevant conditions.

Click chemistry has built its reputation on reliability – fast, selective reactions that work even in messy biological environments. But the permanent bonds it creates can limit applications such as drug delivery and responsive biomaterials, where connections may need to come apart on demand.