[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.
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.
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.
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).
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
Bar-Ilan University, Ramat-Gan, Israel