C2-Arylated Indoles and Benzofurans through Formal (4 + 1) Annulation of -Sulfonyl-2-aminobenzaldehydes and Salicylaldehyde Derivatives with Electron-Deficient Benzyl Chlorides.

A two-step formal (4 + 1) annulation-dehydration reaction offers a convenient route to C2-arylated indoles and benzofurans. This reaction exploits the bifunctional reactivity of electron-deficient benzyl chlorides with -sulfonyl-2-aminobenzaldehydes or salicylaldehyde derivatives. The reaction tolerates both electron-withdrawing and donating groups on the substituted aldehydes, as well as variation of electron-withdrawing groups at the position of the benzyl chloride reagent.