C(sp 3 )–H methylation enabled by peroxide photosensitization and Ni-mediated radical coupling

Adding methyl groups with good timing In pharmaceutical research, swapping out hydrogens for methyl groups is a frequent strategy to optimize small-molecule properties. Vasilopoulos et al. report a versatile, convenient, and comparatively safe method for methylation of carbon centers adjacent to nitrogen or aryl rings. Under carefully optimized conditions, di-tert-butyl peroxide plays a dual role as oxidant and methyl source. Cleaving the O–O bond through photosensitization produces butoxyl radicals, some of which cleave substrate C–H bonds, whereas others release methyl radicals that a nickel catalyst delivers to those activated substrates. Science , this issue p. 398