Chem. Sci., 2025, Accepted Manuscript DOI: 10.1039/D5SC07347B, Edge Article Kyosuke Fujiwara, Shogo Nakamura, Koji Hirano An oxygen-umpolung-enabled, regioselective and stereospecific copper-catalyzed methoxyboration of styrenes with diborons and acetal-based methyl peroxide has been developed. The use of designed peroxide enables the otherwise difficult two-electron redox event...