Redox catalysis in a ball mill

Mixing solid reactants in a ball mill is a promising means of avoiding the copious solvent waste associated with most chemical syntheses. Kubota et al. now report that adding a piezoelectric catalyst to the mix can promote bond formation through apparent electron transfer cycles (see the Perspective by Xia and Wang). Specifically, barium titanate activates aryl diazonium salts toward borylation and coupling with heterocycles in a manner reminiscent of solutionphase photoredox catalysis. The reactions are insensitive to air and were demonstrated up to gram scale.

Science, this issue p. 1500; see also p. 1451