Regioselective Dearomative Amidoximation of Nonactivated Arenes Enabled by Photohomolytic Cleavage of N‐nitrosamides

Dearomative spirocyclization reactions represent a promising means to convert arenes into three‐dimensional architectures; however, controlling the regioselectivity of radical dearomatization with nonactivated arenes to afford the spirocyclizative 1,2‐difunctionalization other than its kinetically preferred 1,4‐difunctionalization is exceptionally challenging. Here we disclose a novel strategy for dearomative 1,2‐ or 1,4‐amidoximation of (hetero)arenes enabled by direct visible‐light‐induced homolysis of N−NO bonds of nitrosamides, giving rise to various highly regioselective amidoximated spirocycles that previously have been inaccessible or required elaborate synthetic efforts. The mechanism and origins of the observed regioselectivities were investigated by control experiments and density functional theory calculations. Reported is a novel method to realize a highly regioselective dearomative difunctionalization for the synthesis of various spirocycles. The nonredox homolysis, the reversible radical coupling, and the nitroso‐oxime tautomerism promote the chemoselectivity of dearomative 1,2‐ or 1,4‐amidoximation.