Rongalite‐Promoted on Water Synthesis of Functionalised Tellurides and Ditellurides

Abstract

The on water reaction of sodium telluride with electrophiles has been explored. Na2Te, generated in situ through the rongalite (sodium hydroxymethanesulfinate)‐promoted reduction of elemental tellurium, reacts with a wide variety of electrophiles, including strained heterocycles, haloalkanes, Michael acceptors, and aryl diazonium salts, providing simple and rapid access to a broad range of novel functionalised symmetrical tellurides. The methodology well tolerated the presence of versatile functional groups such as alchohols, amines, esters, nitriles, and sulfones and allowed the incorporation of tellurium atoms into biologically relevant natural‐derived products. Furthermore, in the case of the nucleophilic ring opening of epoxides and aziridines, a judicious tuning of the reaction conditions enabled the synthesis of unreported β‐hydroxy‐ and β‐amino‐ditellurides, which were further employed as precursors of new functionalised unsymmetrical dialkyl tellurides. The thiol−peroxidase catalytic activity of hydroxy‐ditellurides has also been investigated in order to compare their antioxidant properties with those of homologous tellurides.

New Dimensions in Rongalite Chemistry: The Land of Opportunities in Organic Synthesis and Material Sciences

“…On the other hand, quite recently, Tanini, Ricci and Capperucci have reported a range of functionalized tellurides 248 and ditellurides 249 from epoxide 246 in a regioselective manner through on water synthesis using cheap and powerful reducing agent namely, rongalite . They began their journey from the preparation of sodium telluride (Na 2 Te) using Tschugaeff's procedure from rongalite and elemental tellurium.…”

Unexpected Ethyltellurenylation of Epoxides with Elemental Tellurium under Lithium Triethylborohydride Conditions

“…Attracted by the synthetic utility and versatility of organotellurium compounds, we recently moved to evaluate the chemistry of tellurium-centered nucleophiles with strained heterocycles [46,49]. The poor stability of (Me 3 Si) 2 Te [48,49] prompted us to employ dilithium telluride and dilithium ditelluride, generated from elemental tellurium and lithium triethylborohydride (superhydride), as tellurenylation reagents for the NRORs of epoxides and aziridines [49].…”

“…On the basis of these results, we next turned our attention to evaluating whether under the studied conditions ditellurides 3 could behave as precursors of β-hydroxy-alkyl ethyl tellurides 2. We recently developed an on-water methodology to access functionalised dialkyl ditellurides from elemental tellurium, sodium hydroxymethanesulfinate, and strained heterocycles [46]. Therefore, we employed this route to prepare β-hydroxy-ditelluride 3a and then we studied its reactivity with organoboranes.…”

“…Ditelluride 3a [46] and diselenide 6a [47] were prepared from 2-((benzyloxy)methyl)oxirane according to procedures reported in the literature.…”

Synthesis of functionalised organochalcogenides and in vitro evaluation of their antioxidant activity

“…Chalcogen containing small molecules and enzymes play a crucial role in a wide range of biological functions and biochemistry mechanisms. Organoselenium derivatives have been attracting considerable interest because of their capability to mimic natural biologically active compounds and for their antioxidant, [5][6][7][8][9] antitumoral, [10,11] antiviral, [12] anti-inflammatory [13,14] activities. Organic chalcogenides (especially selenides) have been also widely applied as synthetic mimics of glutathione peroxidase, but, while biological properties of a number of organoselenium derivatives have been described, a little is known about the biological and pharmacological effects of organotellurium compounds.…”