Synthetic Approaches to Selenoesters and Chalcogen Compounds

Selenoesters and wider chalcogen compounds have attracted sustained interest owing to the distinctive reactivity of selenium in comparison with its lighter homologue sulphur and heavier analogue tellurium. Selenoesters, generally defined by the functional group R–C(=O)–Se–R′, are key intermediates in the construction of complex molecules and are prized for their heightened electrophilicity, facile cleavage under mild reducing conditions and potential antioxidant activity. Syntheses typically proceed via nucleophilic substitution of acyl halides with selenolate anions derived from diselenides or elemental selenium, metal-mediated couplings using zinc or magnesium chalcogenates, and addition of alkynylchalcogenolates to activated glycerol derivatives. Complementary cyclisation strategies give access to selenolactones, selenadiazoles and benzoselenophenes. Recent efforts have focused on atom-efficient and environmentally benign protocols, exploiting “on-water” media, ultrasound irradiation and solvent-free conditions to minimise waste and energy consumption. Control over stereochemistry and scale-up for gram-scale diselenide and selenol ester production have also advanced, opening pathways to pharmaceutical precursors, redox catalysts and functional materials with tunable electronic properties. Interconversion among sulphur, selenium and tellurium congeners further enables systematic modulation of reactivity and biological activity.

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Synthetic Approaches to Selenoesters and Chalcogen Compounds publication trend

The graph below shows the total number of articles in synthetic approaches to selenoesters and chalcogen compounds across all publications each year (not limited to Nature Index journals).

Technical terms

Selenoester: An ester analogue in which the oxygen atom of the alkoxy group is replaced by selenium, R–C(=O)–Se–R′.

Chalcogen: Any member of group 16 of the periodic table, notably oxygen, sulphur, selenium and tellurium, distinguished by their varied bonding and redox properties.

Selenolate: The anionic form R–Se⁻, typically generated by reduction of diselenides or deprotonation of selenols, acting as a nucleophile in esterification.

Diselenide: A compound containing an Se–Se bond (R–Se–Se–R), often used as a precursor to selenolate species.

On-water conditions: A protocol in which reactions are carried out in aqueous suspension without complete solubility of organic reagents to enhance selectivity and sustainability.

Ultrasound-assisted synthesis: A technique utilising high-frequency sound waves to promote reaction rates, improve yields and reduce reaction times through cavitation effects.

References

1. Atom Efficient Preparation of Zinc Selenates for the Synthesis of Selenol Esters under “On Water” Conditions. Molecules (2017).
2. Glycerol as Precursor of Organoselanyl and Organotellanyl Alkynes. Molecules (2017).
3. Ultrasound-assisted synthesis of alkali metals diselenides (M2Se2) and their application for the gram-scale preparation of 2,2'-diselenobis(benzoic acid). Arkivoc (2019).