A Practical Synthesis of Indoles via a Pd-Catalyzed C−N Ring Formation

A method for the synthesis of N-functionalized C2-/C3-substituted indoles via Pd-catalyzed C–N bond coupling of halo-aryl enamines is described. The general strategy utilizes a variety of amines and β-keto esters which are elaborated into halo-aryl enamines as latent precursors to indoles. The preferred conditions comprising the RuPhos precatalyst and RuPhos in the presence of NaOMe in 1,4-dioxane tolerate a variety of substituents and are scalable for the construction of indoles in multigram quantities.