ORTHO-LITHIATION OF PHENYLTHIOETHERS—AND SOME APPLICATIONS

Abstract
A preparative procedure for the ortho-lithiation of phenylthioethers C6H5SR 1 is described. The preparations of 2-alkylthio-substituted benzoic acids 3, benzophenones 5 and phenylphosphines 6 were carried out in isolated yields of 38–73%, depending on reaction and substituent. The procedure provides a simple route to dithiocatechol and trithiopyrogallol derivatives 7 and 8. The ring-lithiation step gives the best results for R = t-C4H9 (80–90%) and R = i-C3H7 (70–80%). R = C2H5 gave lower yields (ca. 45%), while R = CH3 gave principally lithiation at alkyl carbon.