azide | Amine | Chemical Reactions

The scope and limitations of δ-carbolinium ion generation was examined by exposing a series of aryl azides 1 to the optimal reaction conditions. The azides for our study were synthesized in three steps from commercial 2-bromoanilines through a Suzuki cross coupling–azidation–methylation sequence.[] We found that our amination reaction tolerated a range of substituents on the aryl azide portion of the substrate: azides bearing alkyl- and trifluoromethyl groups as well as halides were efficiently converted into δ-carbolinium ions (). The reaction was even tolerant of substitution adjacent to the azide (entry 8). While a range of groups was tolerated on the azide portion of the substrate, the reaction yield was severely attenuated if any additional substituents were added to the pyridinium ion moiety.

T1 - A simple and effective synthesis of aryl azides via arenediazonium tosylates
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This report describes an improvement of the diazotransfer reaction and the first example of a regioselective azide reduction of compounds containing multiple azides.


Azide synthesis by azidonation, azidation or substitution

03/11/2017 · Rapid Synthesis of Aryl Azides from Aryl Halides under Mild Conditions
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With the successful synthesis of 1-methyl-δ-carbolinium triflates 2, the conversion of aryl azides bearing 4-substituted pyridinium ion ortho-substituents into β-carbolinium ions (5) was next attempted. To our delight, the rhodium(II)-catalyzed C–H bond amination conditions proved amenable to the synthesis of 5 from aryl azides 4 (). Subsequent reduction of the β-carbolinium ion with NaBH4 produced tryptoline 6, which was easily purified using silica gel column chromatography. The alkyl group on the pyridine nitrogen atom could be varied without attenuating the yield of the process as long as a stoichiometric amount of AgOTf was added (entries 2 and 3). The steric environment around azide could be increased through substitution without preventing product formation (entry 4). The electronic nature of the aryl azide could also be modulated without adversely affecting the reaction (entries 6–10): both electron donating- and electron-withdrawing groups were tolerated in the method. Importantly, meta-substituents could be appended to the aryl azide without compromising the yield of the reaction (entries 9 and 10). The resulting tryptolines 6i and 6j cannot be formed selectively from a Fischer indole synthesis.[]