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.