Deoxygenative Sulfonation Of 7-azaindole-Nitrogen Oxide

Nitrogen-containing heterocyclic compounds are widely found in natural products and organo-synthetic drug molecules,while 3-thioetherindole compounds act as core structural units of anti-HIV drugs,are widely used in the medical field due to their characters of inhibiting microtubulin polymerization and cell growth.In recent years,the construction of carbon-hetero bonds is mainly realized by the cross-coupling reaction of halide and reagents containing hetero atoms catalyzed by transition metals.However,the thioetherification reaction generally has the following disadvantages: the excessive thioetherification reagents and additives,the high reaction temperature,the narrow substrate compatibility range,the low yield and environmental unfriendly.We chose 7-azaindole-7-nitrogen oxide as the substrate and internal oxidant,equimolar disulfide as the thioetherification reagent,and the deoxythioetherification reaction was carried out in absolute ethanol using inexpensive non-metal iodine as the catalyst.This idea not only avoids the use of unnecessary additives and simplifies the experimental process,but also applies indoles as nitrogen oxides to synthesize 3-thioether-based anthracene derivatives for the first time.This approach opens up a new route for thioetherification of azindole.In this paper,the effects of solvent,feed ratio,temperature and iodine dosage on the synthesis of 3-thioether-7-azaindoles were studied.Twenty-four 7-azindole-N-nitrogen oxides and their derivatives were synthesized,eleven of which were first synthesized;under the optimal conditions,a total of 42 deoxythioetherification products were obtained,32 of which were synthesized for the first time.In addition,based on the analysis and summary of the reaction results,the possible mechanism of the deoxythioetherification of 7-azaindole-7-nitrogen oxide was proposed.