An Efficient Method for the Selective Syntheses of Sodium Telluride and Symmetrical Diorganyl Tellurides and the Investigation of Reaction Pathways

Studies on organotellurium compounds have not been extensively conducted due to a lack of tolerable synthetic methods, difficult isolation processes, and their chemical instabilities. Overcoming these hurdles, we developed an efficient and mild method for the selective synthesis of symmetrical diorganyl tellurides <b>1</b>, a representative class of organotellurium compounds, using a proper reducing reagent. The reaction condition was optimized for the selective formation of <b>1</b> by forming the telluride dianion (Te^2-) using a reducing reagent, sodium borohydride (NaBH₄), and then followed by the addition of organyl halides. The optimized reaction condition was as follows: (1) Te (1.0 eq), NaBH₄ (2.5 eq) in DMF for 1 h at 80 °C; (2) organyl halides (2.0 eq) for 3-5 h at 25-153 °C. Using this condition, 18 various diorganyl tellurides <b>1</b> were selectively and efficiently synthesized in reasonable yields (37-93%). The reaction pathways for the formation of diorganyl tellurides <b>1</b> were also investigated. Consequently, we established a practical and efficient method for the selective synthesis of diorganyl tellurides <b>1</b> as a representative class of organotellurium compounds.