Violet-light-induced ring expansion of 2-aryl-1,3-indandiones with chlorodiazirines toward 1,4-naphthoquinones.

1,4-Naphthoquinones are widely used in medicine and materials, but noble metal catalysts and harsh conditions limit their synthesis. We report a violet-light-induced skeletal editing strategy that enables ring-expansion of 2-aryl-1,3-indandiones via single-carbon insertion using chlorodiazirines as carbene precursors. This protocol proceeds without metal catalysts or ligands, featuring broad substrate scope, excellent selectivity, high efficiency under mild conditions, and moderate to good yields. Mechanistic studies indicate that the reaction proceeds via carbene [2 + 1] cycloaddition, followed by ring expansion.