However, researchers from Boehringer-Ingelheim were able to successfully use both " o "-bromoanilines and " o "-chloroanilines to form indoles by using N-methyl-2-pyrrolidone ( NMP ) as the solvent with 1, 1'bis ( di-tert-butylphosphino ) ferrocene as the NMP ligand . " O "-bromoanilines and " o "-chloroanilines are more readily available and cost-effective over using " o "-iodianiline in Larock indole synthesis.
