1.1: toluene-4-sulfonic acid / tetrahydrofuran / 2 h / Inert atmosphere; Reflux 2.1: tributylphosphine; di-isopropyl azodicarboxylate / tetrahydrofuran / 12 h / 4 - 25 °C / Inert atmosphere 3.1: tris-(dibenzylideneacetone)dipalladium(0); tri-tert-butyl phosphine; potassium carbonate / toluene / 16 h / 110 °C / Inert atmosphere 3.2: 16 h / 0 - 25 °C / Inert atmosphere 4.1: 1-hydroxy-3H-benz[d][1,2]iodoxole-1,3-dione / N,N-dimethyl-formamide / 16 h / 0 - 25 °C / Inert atmosphere 5.1: trifluoroacetic acid / dichloromethane / 1 h / Inert atmosphere 6.1: water / acetonitrile / Inert atmosphere; Acidic conditions View Scheme