13 - Formation of Carbon-Sulfur, Carbon-Selenium and Carbon-Tellurium Bonds via Organomagnesium Compounds

Abstract

This chapter describes the formation of carbon–sulfur, carbon–selenium and carbon–tellurium bonds via organomagnesium compounds. In contrast with the dearth of methods for obtaining carbon–oxygen bonds from organomagnesium compounds, there is a variety of methods for obtaining carbon–sulfur bonds. They include reactions with sulfur–sulfur-bonded compounds (including elemental sulfur), reactions involving nucleophilic displacement from sulfur halides and related compounds, reactions with compounds containing sulfur–oxygen double bonds, and thiophilic addition to thiocarbonyl groups. The reaction of organomagnesium compounds with sulfur (usually S8) can give a range of polysulfides as well as the thiolate. The thiolate is the main product if an excess of sulfur in solution is avoided. The addition of flowers of sulfur to a Grignard reagent is usually satisfactory. The thiolate may then be hydrolyzed to the thiol, or converted in situ into other derivatives. Analogous reactions with selenium also give satisfactory yields of selenols or derivatives, and one or two examples of analogous reactions of tellurium have also been reported. The product is a new organomagnesium compound, which may be used in situ for further reactions; reactions with dithioesters are particularly useful, giving functionalized dithioketals.