Aryl pinacol boronates are important synthons in organic synthesis. Radical reactions of alkyl catechol boronates offer the possibility to synthesize N-, S-, O- and F-alkyls, while Suzuki- Miyaura reaction has been explored for bioorthogonal protein labelling and drug synthesis in living cells. Here, we show an intriguing reactivity of aryl pinacol boronates with peptides and protein disulfide bonds under aqueous conditions. The reaction can be carried out by N,N- dimethylacetamide (DMA) or ammonium persulfate (APS) and allows a proteome-wide, protein and peptide derivatization. We show the efficient reaction of various disulfides, using different aryl pinacol boronates. This approach opens up a new possibility for protein derivatization, covalent drug designs and organic synthesis.