Styryl azide

Formation of 2//-azirines by thermal decomposition of vinyl azides has been shown to exhibit small entropy of activation and insensitivity to solvent polarity acyclic vinyl azides decompose more readily than analogous cyclic ones and it is advantageous to have a hydrogen atom cis to the azido group ( -are more reactive than Z-isomers). These results and the linear correlation found for ring-substiment effects on decomposition of a-styryl azides are consistent with a nonconcerted mechanism in which elimination of nitrogen and cyclization into a three-membered ring proceeds synchronously. 

Both a- and / -styryl azides undergo regioselective addition to enamines to provide l-vinyl-5-aminotriazolines in moderate yields.222 1-Pyrrolidinyl enamines react with a-styryl azide more readily than piperidino or mor-pholino enamines /J-styryl azide is as reactive as phenyl azide, a-styryl azide less so.222... 

Terminal vinyl azides give, upon decomposition, vinylnitrenes which can stabilize by rearrangement to nitriles. The pyrolysis of jS-styryl azide (73) afforded in this manner phenylacetonitrile (74) (74%) Nitriles were also obtained from a-azidoketenes (75) gene-... 

The following are examples of use of less common azides. Vinyl azides, including /S-styryl azide, gave excellent yields in the tert-butoxide method (see above), and -haloalkyl azides could be used in their place (70JHC361 ... 

After a month at room temperatiu-e, a-styryl azide is transformed into a mixture of 2-phenylazirine and 2,5-diphenylpyrrole, along with a small amount of 3,6-diphenylpyridazine. The formation of the pyridazine is explained by reaction of two molecules of the azide to give the azo compound 116, with subsequent ring closure and aromatization to 117. Later, the... 

Boyer22 reported the formation of phenylacetonitrile by photolysis or pyrolysis of / -styryl azide (4), photolysis of /S-styryl isocyanate, and triethyl phosphite deoxygenation of / -nitrostyrene. A nitrene mechanism was proposed (Eq. 2). 

Disubstituted indoles have been prepared by rhodium carboxylate-catalysed reactions of jS,jS-disubstituted styryl azides (Scheme 145). ... 

A sizable number of reports describe carbocationic chemistry initiated by transition metal catalysts. This includes a variety of cyclization and ring-opening transformations. For example, a Rh2(II)-catalyzed synthetic method has been developed as a means of preparing 2,3-disubstituted indoles from styryl azides (Scheme 30)7 The chemistry... 

Rh2(II)-carboxylate complexes have been reported to promote the selective migration of aminomethylenes in )5,)5-disubstituted styryl azides to form 2,3-disubstituted indoles with stepwise migration before diffusion of the iminium ion (Scheme 155). ... 

The copper-catalyzed reaction of j8-styrylboronic acid with sodium azide afforded ( )-j8-styryl azide in good yield. In rare cases, the rearrangement of butatrienylidene and alkynyl complexes of iridium led to special enazides. A single example of the formation of an alkenyl azide via palladium-catalyzed cyclization of an allenic substrate has also been reported. ... 

Shen T, Wang T, Qin C, Jiao N (2013) Silver-catalyzed nitrogenation of alkynes a direct approach to nitriles through C=C bond cleavage. Angew Chem Int Ed 52(26) 6677-6680 Kadaba PK (1990) TriazoUnes XX. Vinyl azides as dipolarophiles in 1,3-dipolar cycloadditions intermolecular cycloaddition of hydrazoic acid and a-styryl azide to give a tetrazole. Synlett 6 349-351... 

---