Synthesis, Mechanism Elucidation and Biological Insights of Tellurium(IV)‐Containing Heterocycles

Abstract

Inspired by the synthetic and biological potential of organotellurium substances, a series of five-and six-membered ring organotelluranes containing a TeÀ O bond were synthesized and characterized. Theoretical calculations elucidated the mechanism for the oxidation-cyclization processes involved in the formation of the heterocycles, consistent with chlorine transfer to hydroxy telluride, followed by a cyclization step with simultaneous formation of the new TeÀ O bond and deprotonation of the OH group. Moreover, theoretical calculations also indicated anti-diastereoisomers to be major products for two chirality center-containing compounds. Antileishmanial assays against Leishmania amazonensis promastigotes disclosed 1,2λ 4 -oxatellurane LQ50 (IC 50 = 4.1 � 1.0; SI = 12), 1,2λ 4 -oxatellurolane LQ04 (IC 50 = 7.0 � 1.3; SI = 7) and 1,2λ 4 -benzoxatellurole LQ56 (IC 50 = 5.7 � 0.3; SI = 6) as more powerful and more selective compounds than the reference, being up to four times more active. A stability study supported by 125 Te NMR analyses showed that these heterocycles do not suffer structural modifications in aqueousorganic media or at temperatures up to 65 °C.

Hybrid Quinoline Telluroether Ligand Derived Copper and Silver Complexes: Synthesis, Structural and Electronic Properties

“…However, in the metal complexes 4 – 7 , the methylene carbon appeared in deshielded region at δ −23 ppm compared with telluroether 3 . The 125 TeNMR spectrum of ditelluride 2 displays a significantly upfield chemical shift at δ 158 ppm in comparison to the previously reported diaryl ditellurides; diphenyl ditelluride (422 ppm), [40] dinaphthyl ditelluride (334 ppm), bis( N,N dimethylbenzylamine) ditelluride (375 ppm), bis[2‐(4,4‐dihydro‐2 oxazolinyl) phenyl] ditelluride (420 ppm). However, 125 Te NMR chemical shift value of 2 is comparable with di(2‐methyl‐naphthyl) ditelluride (182 ppm) and bis[2,5‐dimethyl‐4‐ tert ‐butylphenyl] ditelluride (198 ppm).…”