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EDT in Organic Synthesis

Review Article

1,2-Ethanedithiol application review · CAS 540-63-6

Last updated: October 2026

Abstract

1,2-Ethanedithiol is one of the most versatile bifunctional sulfur reagents in preparative organic chemistry. This review surveys its use in 1,3-dithiolane formation, carbonyl protection strategies, dithiine and dithiole synthesis, and thiol-ene click chemistry, and outlines recent advances that extend its role toward polymer and materials chemistry.

1.11,3-Dithiolane Formation

The condensation of EDT with aldehydes and ketones produces 1,3-dithiolanes, five-membered cyclic dithioacetals that are widely used as carbonyl protecting groups. The reaction proceeds under acid catalysis with continuous removal of water, and the resulting ring is remarkably stable toward bases and nucleophiles (Wuts, 2014).

R₂C=O + HSCH₂CH₂SH → R₂C(SCH₂CH₂S) + H₂O

Reaction 1. Acid-catalysed formation of a 1,3-dithiolane from EDT.Conditions: p-TsOH or BF₃·OEt₂, refluxing toluene, Dean–Stark water removal.

1.2Carbonyl Protection Strategies

Because the dithiolane ring resists both strong base and hydride reagents, EDT is preferred when a carbonyl must survive multi-step sequences. Deprotection is achieved oxidatively with NBS or with mercury(II) salts, restoring the carbonyl under conditions that are orthogonal to many other protecting groups.

The small size of the C₂ backbone and the high nucleophilicity of the two thiols give fast, clean conversions even for sterically hindered ketones (Wuts, 2014).

1.3Dithiine & Dithiole Derivatives

Under oxidative conditions the intermediate dithiolate can be elaborated into 1,4-dithiines and dithioles, heterocycles valued as building blocks for conductive materials and as sulfur-rich synthons. Control of the oxidant and temperature determines whether the product closes through intramolecular coupling or remains as open-chain disulfide oligomers.

1.4Thiol-Ene Click Chemistry

Both terminal S–H bonds participate in radical thiol-ene addition to unactivated alkenes and in base-catalysed thiol-Michael addition to activated alkenes. The reaction is fast, relatively insensitive to oxygen inhibition and free of metallic catalysts, making EDT an efficient cross-linker for network formation (Hoyle & Bowman, 2010).

HSCH₂CH₂SH + 2 CH₂=CH–R → R–CH₂CH₂–S–CH₂CH₂–S–CH₂CH₂–R

Reaction 2. Double thiol-ene addition across the two thiol groups of EDT.Conditions: DMPA photoinitiator with UV light, or a tertiary amine catalyst at ambient temperature.

1.5Recent Advances

Practical protocols increasingly combine dithiolane protection with flow processing and catalytic deprotection, which lowers mercury waste and improves atom economy. The same bifunctional reactivity is used to install sulfur anchors on polymer backbones and on solid supports, connecting classical protection chemistry to materials design.

References

  1. Hoyle, C. E., & Bowman, C. N. (2010). Thiol-ene click chemistry. Angewandte Chemie International Edition, 49(9), 1540–1573.
  2. Wuts, P. G. M. (2014). Greene's protective groups in organic synthesis (5th ed.). Wiley.

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