CsPbBr3 Perovskite Photocatalyst in Chemodivergent Functionalization of N‑Methylalkanamides Using CBr4

Herein we have developed a strategy for chemodivergent functionalization of N-methylalkanamides via C–Br bond activation of CBr4, using an orthorhombic CsPbBr3 perovskite photocatalyst under blue LEDs (450–470 nm). The selectivity of whether a 5-exo-trig spiro cyclization or a 6-endo-trig cyclization occurred depended on the stability of the radical intermediate that was formed after the addition of the bromide radical to the starting compound to obtain 3,8-dibromo-1-methyl-4-phenyl-1-azaspiro[4.5]deca-3,6,9-trien-2-on or 3-bromo-1-methyl-4-phenyl-1-azaspiro[4.5]deca-3,6,9-triene-2,8-dione or 3-bromo-6-(tert-butyl)-1-methyl-4-phenylquinolin-2(1H)-one.