Triazenes

Triazenes are organic compounds that contain the functional group R1−NN=N−NR2R3, where the R are each any of various types of substituent groups.[2] Some anti-cancer medications and dyes are triazenes.[3] Formally, the triazenes are related to the unstable chemical triazene, H2N−N=NH.

Dacarbazine is a triazene used in the treatment of melanoma and Hodgkin's lymphoma.[1]

Production

Triazenes are prepared from the N-coupling reaction between diazonium salts and primary or secondary amines.[4] The coupling reactions are typically mild, using a base such as sodium acetate,[5] sodium carbonate,[5] or sodium bicarbonate.[4]

The diazonium reagents are themselves available starting from amines. For symmetrical triazenes derived from primary amines, partial diazotization gives a mixture of the original amine and its diazo derivative that then couple with each other. For example, 1,3-diphenyltriazene (PhN=N−NHPh) can be made from aniline in a one-pot reaction.[5][6] For asymmetrical triazenes, for example (phenyldiazenyl)pyrrolidine (PhN=N−NC4H8), the diazonium salt must be pre-made.

Azo N-coupling

Analogues of Tröger's base containing a symmetric pair of asymmetric triazene side-chains have been obtained similarly.[7]

Bis-triazene analogue of Tröger's base

Reactions and applications

Triazenes derived from primary amines engage in tautomerism. In the case of symmetric triazenes, the tautomers are identical.

Tautomerism of triazenes derived from primary amines

Triazenes can be converted to diazonium salts.[8]

Triazenes used in the synthesis of thiophenols

Triazenes decompose in the presence of protonating or alkylating agents into quaternary amines and diazonium salts; as such triazenes have been used as an in situ source of diazonium that reacted with sodium sulfide to give the corresponding thiophenols.[5] A strategy for the protection and deprotection of sensitive secondary amines is based on this principle.[9]

Polymeric triazenes are applied as conductive and absorbent materials.[10] Triazenes have been used in the synthesis of cinnoline, functionalized lactams, and coumarins.[9][8]

References
  1. "Dacarbazine". The American Society of Health-System Pharmacists. Archived from the original on 11 September 2017. Retrieved 8 December 2016.
  2. Suleymanov, Abdusalom A.; Severin, Kay (2021-03-22). "Vinyl and Alkynyl Triazenes: Synthesis, Reactivity, and Applications". Angewandte Chemie International Edition. 60 (13): 6879–6889. doi:10.1002/anie.202011031. ISSN 1433-7851.
  3. Berneth, Horst (2008). "Methine Dyes and Pigments". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a16_487.pub2.
  4. Sengupta, Saumitra; Sadhukhan, Subir K. (2002). "Synthesis of Symmetrical trans-Stilbenes by a Double Heck Reaction of (Arylazo)amines with Vinyltriethoxysilane: trans-4,4′-Dibromostilbene". Organic Syntheses. 79: 52. doi:10.15227/orgsyn.079.0052.
  5. Kazem-Rostami, M.; Khazaei, A.; Moosavi-Zare, A. R.; Bayat, M.; Saednia, S. (2012). "Novel One-Pot Synthesis of Thiophenols from Related Triazenes under Mild Conditions". Synlett. 23 (13): 1893–1896. doi:10.1055/s-0032-1316557. S2CID 196805424.
  6. Hartman, W. W.; Dickey, J. B. (1934). "Diazoaminobenzene". Organic Syntheses. 14: 24. doi:10.15227/orgsyn.014.0024.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. Kazemostami, Masoud (2017). "Facile preparation of Ʌ-shaped building blocks: Hünlich-base derivatization". Synlett. 28: 1641–1645. doi:10.1055/s-0036-1588180. S2CID 99294625.
  8. Kimball, D. B.; Haley, M. M. (2002). "Triazenes: A Versatile Tool in Organic Synthesis". Angewandte Chemie International Edition. 41 (18): 3338–51. doi:10.1002/1521-3773(20020916)41:18<3338::AID-ANIE3338>3.0.CO;2-7. PMID 12298030.
  9. Lazny, R.; Poplawski, J.; Köbberling, J.; Enders, D.; Bräse, S. (1999). "Triazenes: A Useful Protecting Strategy for Sensitive Secondary Amines". Synlett. 1999 (8): 1304–1306. doi:10.1055/s-1999-2803.
  10. Khazaei, A.; Zare, A.; Moosavi-Zare, A. R.; Sadeghpour, M.; Afkhami, A. (2013). "Synthesis, characterization, and application of a triazene-based polysulfone as a dye adsorbent". Journal of Applied Polymer Science. 129 (6): 3439–3446. doi:10.1002/app.39069.
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