Synthesis of 1H‑Indole-2,3-dicarboxylates via Rhodium-Catalyzed C–H Annulation of Arylhydrazines with Maleates

This work describes a one-step synthesis of 1H-indole-2,3-dicarboxylates through C–H activation. Rhodium-catalyzed tandem C–H activation and annulation of 2-acetyl-1-phenylhydrazines with maleates proceeded smoothly in the presence of additive NaOAc and oxidant Ag2CO3 and produced the corresponding indole derivatives, 1H-indole-2,3-dicarboxylates, in satisfactory to good yields. A variety of useful functional groups were tolerated on the benzene ring including halogen atoms (F, Cl, Br, and I) and methoxycarbonyl groups.