Fluoroalkanesulfonyl azides

Fluoroalkanesulfonyl azides 281 add readily to vinyl ethers to provide triazolines 282 in good yield (67-84%). At room temperature, slow decomposition of the products is observed with evolution of nitrogen and formation of piperazine derivatives 284. No other products are observed. Formation of piperazines 284 must involve cleavage of the triazoline ring with formation of zwitterionic intermediates 283 (Scheme 42) <2004JFC(125)445>. 

Xu, Y., Wang, Y., Zhu, S. Reactions of fluoroalkanesulfonyl azides with carbocyclic 3-keto esters structural influence of dicarbonyl substrate on distribution of diazo and ring-contraction products. J. Fluorine Chem. 2000,105, 25-30. 

Very few reports have been published to date on the reactions of indoles with NNN dipoles. The reaction of fluoroalkanesulfonyl azides 193 with indoles 192 results in the formation of distinct amino, imino or diazo products, 195-198 depending on the choice of solvent and the nature of substituents on the indole ring (Scheme 54). When the indole has a methyl group in the 2 or 3 position, compounds 196 or 195 are obtained, respectively. If the 2 and 3 position are unsubstituted, compounds 197 and 198 are obtained, respectively. In all cases, a dipolar cycloadduct 194 is proposed as an intermediate in the first step in the mechanism of these transformations [85, 86]. 

FluoroaUcanesulfonyl azides in reactions with alkenes are more reactive than alkyl azides because of strong electron-acceptor properties of the sulfonyl group. Thus, Zhu, He et al. shown that the reaction of vinyl ethers with 1-fluoroalkanesulfonyl azides proceeded in mild conditions to afford l-fluoroalkanesulfonyl-5-alkoxy-... 

Zhu S-Z, He P, Zhao J-W, Cai X (2004) Reactions of fluoroalkanesulfonyl azides with vinyl ether and tetrakis(dimethylamino)ethylene. J Fluorine Chem 125 445-450... 

He P, Zhu S-Z (2005) Study on the reactions of fluoroalkanesulfonyl azides with indole derivatives. J Fluorine Chem 126 825-830... 

However, reaction of azides with vinyl ethers often leads to loss of nitrogen with formation of linear products. For example, reaction of fluoroalkanesulfonyl azide with EtOCH=CH2 at room temperature affords the expected [3+2] cycloadduct 56, which decomposes slowly at room temperature. ... 

However, reaction of fluoroalkanesulfonyl azide with cycloalkenylethers proceeds with loss of nitrogen to give linear products. When the reaction is conducted neat at 200 °C, elimination of alcohol with formation of 1,2,3-triazoles in good yields is observed. In contrast, a [3+2] cycloadduct is obtained from from 2,3-dihydropyran and 4-nitrophenyl... 

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