Pd-Catalyzed Indolization/peri-C–H Annulation/N‑Dealkylation Cascade to Cyclopenta-Fused Acenaphtho[1,2‑b]indole Scaffold

A novel Pd-catalyzed cascade reaction of N,N-dialkyl-substituted o-alkynylanilines involving an indolization/peri-C–H annulation/N-dealkylation sequence has been developed to construct a cyclopenta-fused acenaphtho­[1,2-b]­indole (ANI) scaffold. A variety of aromatic hydrocarbons having a peri-C–H bond at the alkynyl terminus, such as naphthalene, phenanthrene, pyrene, and fluoranthene, were employed, affording the corresponding π-extended ANI derivatives. The ANI molecules showed relatively narrow energy gaps by increasing HOMOs and lowering LUMOs, implying their potential applications as π-segments in low-band-gap materials.