[40168-86-3]  · C6H11N3  · 1-Azido-3,3-dimethyl-1-butene  · (MW 125.174)

(used in amination of aromatic and heterocyclic compounds via their lithium derivatives;2 reaction with alkyllithium compounds leads to alkylated ketones;3 reaction with sulfoxonium ylides leads to N-vinyltriazolines and N-vinylaziridines;4 formation of azirines by thermolysis or photolysis5)

Solubility: sol most organic solvents.

Form Supplied in: liquid;6 not available commercially.

Preparative Methods: vinyl azides are prepared in good yield from alkenes by regioselective addition of Iodine Azide (eq 1) followed by elimination of HI with a base such as Potassium t-Butoxide or 1,4-Diazabicyclo[2.2.2]octane.6

Handling, Storage, and Precautions: decomposes on standing; should be handled with care like other azides because of the possibility of explosion.

Amination of Aromatics (NH2 Transfer).

The reaction of vinyl azides with organolithium or Grignard reagents (RLi or RMgX) proceeds at the N-terminal of the azide function to produce an intermediate vinyltriazene, which is usually not isolated but is transformed on workup with dilute acid to an amine when R is aromatic (eq 2). The yield of aminated product is usually only 50-70%, but is the only acid-extractable product; the vinyldiazonium ion byproduct in this reaction is hydrolyzed to an aldehyde or ketone.

While 1-azido-3,3-dimethyl-1-butene often gives better yields, a-azidostyrene and other vinyl azides may also be used (eqs 3 and 4). Theoretically, the reaction of aromatic lithio or Grignard derivatives with any organic azide could lead to NH2 transfer, but in practice vinyl azides, in particular 1-azido-3,3-dimethyl-1-butene and phenylthiomethyl azide,7 are reagents of choice.

1,3-Dimethoxybenzene (1.5 g, 11 mmol) is transformed into its 2-lithio derivative by treatment with 1 equiv of n-Butyllithium in THF at 0 °C for 18 h at rt. Azidostyrene is added at -78 °C and after 2 h at rt the mixture is worked up with 10% HCl and then with KOH to obtain the 2,6-dimethoxyaniline.

Formation of Ketones with Alkyl Transfer.

Unlike the amination of ArLi by means of vinyl azides, the reaction of vinyl azides, including 1-azido-3,3-dimethyl-1-butene, with simple aliphatic RLi compounds leads to alkylated ketones (eq 5).3 In this case, acid-catalyzed decomposition of the vinyltriazene intermediate produces an alkanediazonium ion and an enamine, with subsequent transfer of the alkyl group to the enamine carbon.

Synthesis of Vinyl Heterocycles.

Reaction of vinyl azides, including 1-azido-3,3-dimethyl-1-butene, with trimethylsulfoxonium ylide leads to N-vinyltriazolines. The latter on flash vacuum pyrolysis at ca. 250 °C are transformed into N-vinylaziridines in over 90% yield (eq 6).

Formation of Azirines.

In general, vinyl azides are excellent starting materials for azirines via thermolysis or photolysis (eq 7). In the case of terminal vinyl azides, such as 1-azido-3,3-dimethyl-1-butene, heating leads to polymers or nitriles.5

1. Hassner, A. In Azides and Nitrenes, Reactivity and Utility; Scriven, E. F. V., Ed.; Academic: Orlando, 1984; Chapter 2, pp 35-94.
2. Hassner, A.; Munger, P.; Belinka, B. A., Jr. TL 1982, 23, 699.
3. Belinka, B. A., Jr.; Hassner, A. JACS 1980, 102, 6185.
4. Hassner, A.; Belinka, B. A., Jr.; Haber, M.; Munger, P. TL 1981, 22, 1863.
5. (a) Hassner, A.; Fowler, F. W. JACS 1968, 90, 2869. (b) Hassner, A.; Wiegand, N. H.; Gottlieb, H. E. JOC 1986, 51, 3176.
6. Hassner, A.; Fowler, F. W. JOC 1968, 33, 2686.
7. Trost, B. M.; Pearson, W. H. JACS 1981, 103, 2483.

Alfred Hassner

Bar-Ilan University, Ramat-Gan, Israel

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