One-Pot Synthesis of 2-Sulfanylindoles

Significance

Kobayashi and co-workers report an efficient method for the preparation of 3-acyl-2-(alkylsulfanyl)indoles (R^³ = Me, Et, Ph) and 2-(alkylsulfanyl)indole-3-carboxylates (R^³ = OEt) 2 in a one-pot, three-step sequence starting from 2-(isocyanophenyl) ketones and acetates 1. The reaction proceeds via the in situ generated iso-thiocyanates 3 which, on treatment with base, undergo cyclization to give 2 via disodium salt 4 and trapping with a suitable electrophile. Introducing two equivalents of iodomethane or α,ω-dibromo­alkanes lead to the formation of the dialkyl and fused products 5, respectively. The reaction tolerates both aryl EWGs and EDGs.