Selenated and Sulfurated Analogues of Triacyl Glycerols: Selective Synthesis and Structural Characterization

Abstract

The synthesis of sulfur‐ and selenium‐containing isosters of triacyl glycerols is herein described. Regioselective fluoride‐induced ring‐opening reaction of suitable substituted thiiranes with bis(trimethyl)silyl selenide, followed by in situ S‐ and Se‐acylation with fatty acid acyl chlorides, enables the one pot synthesis of mixed chalcogeno esters in good yield. The key step of this methodology is the functionalization of S−Si and Se−Si bonds of silyl chalcogenides, generated in situ under mild conditions. A related procedure for the synthesis of functionalized selenides, bearing two thiol ester and two ester moieties, was also developed through a fine tuning of the reaction conditions. The physico‐chemical properties of these novel fatty acid chalcogeno esters have been investigated through DSC, SAXS, WAXS, FTIR and polarized optical microscopy, and compared to those of the common triglycerides in order to highlight the effect of the replacement of oxygen with other chalcogen elements in the polar head of the lipid.

Unexpected Ethyltellurenylation of Epoxides with Elemental Tellurium under Lithium Triethylborohydride Conditions

“…During the course of our studies on the reactivity of strained heterocycles with selenium-centered nucleophiles we developed convenient routes towards generating a variety of hydroxy-, amino-, and mercapto-substituted Se-containing systems [50][51][52][53]. For example, through the tuning of the stoichiometry and the conditions of the reaction of (Me 3 Si) 2 Se [(bis(trimethylsilyl)selenide, a synthetic equivalent of hydrogen selenide] with epoxides, thiiranes, and aziridines, we were able to successfully achieve a range of functionalised selenols [50], selenides, and diselenides [47].…”

Synthesis and Applications of Organic Selenols

“…Selective Se-alkylation was achieved upon treatment of the so generated selenolates with alkyl halides or strained heterocycles (Scheme 29). [28,78] Epoxides and N-protected aziridines were also employed as electrophiles, leading to the formation of functionalised unsymmetrical dialkyl selenides through a regioselective nucleophilic ringopening path. Unactivated N-unsubstituted aziridines were also converted into the corresponding unsymmetrical amino-substituted selenides by NROR with selenolate anions, in situ generated from selenols and KOH (Scheme 29).…”

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

“…[35,36] Particularly, the nucleophilic ringopening-reaction of strained heterocycles with tellurium-and selenium-nucleophiles was exploited for the conversion of epoxides, aziridines, and thiiranes into the corresponding organochalcogenides bearing O-, N-, and S-containing moieties. [37][38][39] Notably, some of these compounds exhibited remarkable catalytic antioxidant properties, being capable to mimic the activity of the glutathione-peroxidase enzymatic complex. [40,41] Furthermore, a number of new chalcogen-containing carbonic anhydrase inhibitors [30,42,43] and activators [44] have been designed and synthesised by exploiting the above-mentioned procedures.…”