One‐Pot Synthesis of Pyridyltellurium Derivatives from a Reaction with Isopropylmagnesium Chloride and X‐ray Crystal Structures of Various Pyridyl Ditellurides

A one‐pot synthesis of various symmetrical and unsymmetrical 2‐pyridyl‐, 2‐bromo‐5‐pyridyl‐, and 2,5‐dibromo‐3‐pyridyltellurium compounds has been carried out, at room temperature, by selective single bromine‐magnesium exchange of 2‐bromo‐, 2,5‐dibromo‐ and 2,3,5‐tribromopyridine, respectively, with isopropylmagnesium chloride. This exchange reaction gives the corresponding pyridylmagnesium chlorides, which, upon insertion of elemental tellurium (activated), give the pyridyltelluromagnesium chlorides, and, subsequently, the corresponding dipyridyl ditellurides upon aerial oxidation. The pyridyltelluromagnesium chlorides give unsymmetrical pyridyltellurium derivatives in good yield upon treatment with alkyl halides. The X‐ray crystal structures of bis(2‐pyridyl) ditelluride, bis(2,5‐dibromo‐6‐methyl‐3‐pyridyl) ditelluride and bis(2,5‐dibromo‐3‐pyridyl) ditelluride are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)