Synthetic Developments of Diaryl Ditellurides

Diaryl ditellurides constitute an important class of organotellurium compounds with sig-nificant applications in medicinal chemistry and organic synthesis. They have proven to be power-ful organocatalysts in synthetic transformations and effective molecular fluorescent probes for the recognition of biologically active molecules. Although organotelluride compounds are less ex-plored, they have been described as promising pharmacological agents possessing anticancer, anti-inflammatory, antibacterial, antifungal, antiprotozoal, and antioxidant activities. Additionally, Te-based molecules have shown interesting applications in semiconductors, magnets, and nonlinear optical materials. The increasing interest in tellurium chemistry has been stimulated by recent de-velopments of valuable tellurium-based organocatalysts, which have proven effective in several functional group transformations under sustainable conditions. Moreover, the construction of Te–Te bonds by embedding elemental tellurium into functional moieties via telluration has become a popular research area. The synthetic methodologies are generally high yielding and exhibit notable advantages in terms of regioselectivity, broad substrate scope, excellent functional group tolerance on the aromatic ring, and high conversion ratios. A library of diaryl ditellurides bearing both elec-tron-donating and electron-withdrawing substituents has been afforded by these protocols. Despite the significant synthetic importance of diaryl ditellurides in organic synthesis, few synthetic ap-proaches have been documented in the literature to date. This review article summarizes recent developments in ditelluride synthesis under ligand- and additive-free conditions. The sustainable techniques employed involve the use of non-toxic, low-cost, commercially available reagents and environmentally benign, green solvents.