Phenacyl azide synthesis

M. Keshavarz, R. Badri, A fficile and one pot synthesis of l,4-disubstituted-lH-l,2,3-triazoles from terminal alkynes and phenacyl azides prepared from styrenes by CAN oxidant and sodium azide. Mol. Divers. 15 (2011) 957-962. 

As expected, substitution by azide ion occurs more readily when the alkyl substrate bears electron-withdrawing groups. For example phenacyl bromide and its derivatives give high yields of azides when treated with sodium azide in the cold °. Secondary alkyl substrates undergo Sj,2 reactions with azide ion ° ° but with less facility than primary alkyl substrates in accordance with the normal polar influences and primary steric eflfects in reactions . Selective substitution is therefore possible and this has been effectively applied in carbohydrate and steroid synthesis (sections II.B.5,6). These effects are also exemplified in the alicyclic series where it has been reported that menthyl halides and 2-methylcyclohexyl halides afford unsatisfactory yields of azide ° . The unsubstituted alicyclic azides, however, are obtained in good yields by the procedures outlined above(Table 1). 

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