An efficient one-pot synthesis of 2-aminobenzothiazoles from substituted anilines using benzyltrimethylammonium dichloroiodate and ammonium thiocyanate in DMSO:H2O

Treatment of a variety of substituted anilines with benzyltrimethylammonium dichloroiodate (1.2 equiv) and ammonium thiocyanate (1.0 equiv) in DMSO:H2O (9:1) at 70 °C gave the corresponding 2-aminobenzothiazoles in excellent isolated yields (75–97%; ave. yield for all substrates = 90%). The reaction worked well for 2(4)-mono-, 2,4-di-, or 3,4,5-tri-substituted anilines, and a wide range of both electron donating groups (MeO, HO, CF3O, Me) and electron withdrawing groups (NO2, CN, CO2Et, CO2H, Cl, F) were well tolerated. This method provides a useful alternative to other methods that are either less efficient (requiring 3–7 fold equivalents of reagents) or utilize highly toxic and corrosive liquid Br2 as the oxidizing agent.