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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 1, a representative class of organotellurium compounds, using a proper reducing reagent. The reaction condition was optimized for the selective formation of 1 by forming the telluride dianion (Te2−) 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 1 were selectively and efficiently synthesized in reasonable yields (37–93%). The reaction pathways for the formation of diorganyl tellurides 1 were also investigated. Consequently, we established a practical and efficient method for the selective synthesis of diorganyl tellurides 1 as a representative class of organotellurium compounds.

A new method of Sonogashira coupling reactions between diorganyl tellurides and terminal alkynes is reported. The coupling reactions are performed using Pd(dppf)Cl2 as a catalyst, CuI as a co-catalyst in the presence of K2CO3 in DMSO. The reactions are carried out at room temperature and completed within 2 h when phenyl acetylene is used as a terminal alkyne. For aliphatic terminal alkynes, such as 1-hexyne and 1-octyne, an elevated temperature and longer reaction time are needed for the completion of the reactions. This process results in good yields of Sonogashira coupling products which is applicable for diaryl, divinyl and dialkynyl tellurides but not applicable for dialkyl tellurides. [ABSTRACT FROM AUTHOR]

A simple and highly efficient method for the constructions of Csp-Csp, Csp 2 -Csp 2 and Csp 3 -Csp 3 bonds is reported. The symmetrical diaryl tellurides undergo detellurative homocouplings to afford symmetrical biaryl products. The reactions are carried out at ambient temperature using PdCl 2 as a catalyst in the presence of Ag 2 O and Na 2 CO 3 . Similarly, the detellurative homocouplings of dibenzyl telluride and bis(phenylethynyl)telluride give bibenzyl and the conjugated diyne, respectively. [ABSTRACT FROM AUTHOR]