Thiocyanation Methods in Organic Synthesis

Thiocyanation has emerged as a versatile strategy for the incorporation of the –SCN functionality into organic frameworks, owing to the unique ambident properties of the thiocyanate anion. Both the sulphur and nitrogen termini of SCN– can be engaged selectively in electrophilic, radical and transition-metal-catalysed processes. Key approaches include photoredox-mediated radical addition, Lewis-acid-promoted electrophilic substitution and atom-transfer radical addition, each enabling regio- and chemoselective installation of thiocyanate groups onto alkenes, arenes and heterocycles. Recent advances have extended direct C–H thiocyanation of inert positions, allowing late-stage functionalisation of complex molecules under mild conditions. Photocatalytic and electrochemical methods now offer green and sustainable routes, minimising waste and avoiding hazardous reagents. The resulting aryl and alkyl thiocyanates serve as valuable building blocks for pharmaceuticals, agrochemicals and materials science, where they can undergo versatile post-synthetic transformations into thiols, thioethers and heterocycles. This breadth of methodology underscores the global significance of thiocyanation in enabling rapid access to sulphur-containing motifs with high operational simplicity and wide substrate scope.

Research from Nature Portfolio

Recent studies have demonstrated a photoredox-driven cascade that achieves precise control over ambident thiocyanation and isothiocyanation of simple alkenes. By modulating the redox potential of the photocatalyst, this protocol selectively accesses either C–S or C–N bond formation in a single sequence, furnishing functionalised hydrothiophene and pyrrolidine derivatives from common precursors. Detailed mechanistic investigations, supported by density functional theory, reveal how catalyst redox tuning directs substrates along divergent catalytic cycles, offering a powerful tool for chemodivergent thiocyanation and the synthesis of sulphur- and selenium-containing heterocycles under mild, redox-economical conditions.

Thiocyanation Methods in Organic Synthesis publication trend

The graph below shows the total number of articles in thiocyanation methods in organic synthesis across all publications each year (not limited to Nature Index journals).

Technical terms

Ambident reactivity: The ability of an anion, such as SCN–, to react through two different atoms (sulphur or nitrogen).

Photoredox catalysis: A light-driven process in which a photocatalyst mediates single-electron transfers to generate reactive radical species.

Chemoselectivity: Preference for reaction at one functional group in the presence of others.

Regioselectivity: Preference for bond formation at one position over others in a substrate.

Atom-transfer radical addition (ATRA): A radical process that transfers an atom or group from a reagent to a substrate radical.

C–H activation: Direct functionalisation of a carbon–hydrogen bond without prior functional group installation.

Singlet oxygen: An electronically excited form of O₂ with enhanced reactivity towards organic substrates.

Lewis acid catalysis: Activation of a substrate by an electron-pair acceptor to facilitate bond formation.

References

1. Photocascade chemoselective controlling of ambident thio(seleno)cyanates with alkenes via catalyst modulation. Nature Communications (2024).
2. Copper Photocatalyzed Divergent Access to Organic Thio- and Isothiocyanates. ACS Catalysis (2024).
3. Singlet Oxygen-Mediated Regioselective Thiocyanation of Terminal Alkynes, Alkenes, Indoles, Pyrrole, Anilines, and Phenols. ACS Sustainable Chemistry & Engineering (2024).
4. Regioselective C–H Thiocyanation of Arenes by Iron(III) Chloride Catalysis. The Journal of Organic Chemistry (2023).