The Aza-Wittig reaction or is a chemical reaction of a carbonyl group with an aza-ylide, also known as an iminophosphorane (R3P=NR'). Aza-Wittig reactions are most commonly used to convert aldehydes and ketones to the corresponding imines.[1] The conversion has also been practiced in an intramolecular sense, which is commonly used in the synthesis of N-heterocyclic compounds.[2]
Reaction mechanism
editThe mechanism of the aza-Wittig reaction is analogous to that of the Wittig reaction, with the Wittig reagent replaced by an iminophosphorane.[1]
In some cases, the iminophosphorane is not isolated but generated in situ. In this manifestation, the phosphine, carbonyl, and organic azide are combined
Scope and limitations
editBesides preparing imines from aldehydes and ketones, the aza-Wittig-reaction can also convert carbon dioxide to isocyanates, carbon disulfide to organic thiocyanates, and isocyanates to carbodiimides.[1][3]
There exists solid-supported modifications of the reaction.[4][1][5]
Similar to the Wittig reaction, the reaction suffers from issues with triphenylphosphine oxide by-product removal. Such an issue is mitigated via catalytic aza-Wittig-reactions, some of which entail elements other than phosphorus, like arsenic and tellurium[5][6].
History
editThe reagent for the aza-Wittig reaction, iminophosphorane, was discovered in 1919 by Hermann Staudinger. The reaction itself was discovered thirty years later.[3]
Examples
editAn example of the aza-Wittig-reaction being utilized in organic synthesis is the synthesis of (–)-benzomalvin A. Two intramolecular aza-Wittig-reactions were used to construct the seven-membered ring and the six-membered ring in the molecule's skeleton.[1]
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See also
editReferences
edit- ^ a b c d e Kurti 1 Czako 2, Laszlo 1 Barbara 2 (15 September 2005). Strategic Applications of Named Reactions in Organic Synthesis. Elsevier. pp. 24–25. ISBN 0-12-429785-4.
{{cite book}}: CS1 maint: numeric names: authors list (link) - ^ Wamhoff, Heinrich; Richardt, Gabriele; Stölben, Stephan (1995-01-01), Katritzky, Alan R. (ed.), Iminophosphoranes: Versatile Tools in Heterocyclic Synthesis, Advances in Heterocyclic Chemistry, vol. 64, Academic Press, pp. 159–249, doi:10.1016/s0065-2725(08)60172-5, ISBN 978-0-12-020764-0, retrieved 2024-05-24
- ^ a b "Aza-Wittig Reaction". Retrieved 2024-05-24.
- ^ Hemming, Karl; Bevan, Matthew J.; Loukou, Christina; Patel, Snahal D.; Renaudeau, Denis (2001-02-20). "ChemInform Abstract: A One-Pot Aza-Wittig Based Solution and Polymer-Supported Route to Amines". ChemInform. 32 (8). doi:10.1002/chin.200108116. ISSN 0931-7597.
- ^ a b Lao, Zhiqi; Toy, Patrick H (2016-11-30). "Catalytic Wittig and aza-Wittig reactions". Beilstein Journal of Organic Chemistry. 12: 2577–2587. doi:10.3762/bjoc.12.253. ISSN 1860-5397. PMC 5238588. PMID 28144327.
- ^ Li, Huaifeng; Lupp, Daniel; Das, Pradip K.; Yang, Li; Gonçalves, Théo P.; Huang, Mei-Hui; El Hajoui, Marwa; Liang, Lan-Chang; Huang, Kuo-Wei (2021-04-02). "Redox-Neutral Imination of Alcohol with Azide: A Sustainable Alternative to the Staudinger/Aza-Wittig Reaction". ACS Catalysis. 11 (7): 4071–4076. doi:10.1021/acscatal.1c00379. hdl:10754/668169. ISSN 2155-5435.
External links
edit- Wittig reaction in Organic Syntheses, Coll. Vol. 10, p. 703 (2004); Vol. 75, p. 153 (1998). (Article)
- Wittig reaction in Organic Syntheses, Coll. Vol. 5, p. 361 (1973); Vol. 45, p. 33 (1965). (Article)