Tandem Nitration-Cyclization-Rearrangement of Indole-Tethered 1,6-Enynes To Access NO2-Featured Heterocycles
Zexuan Liu1, Qinqin Yan1, Huaqing Liu1
1State Key Laboratory of New Pharmaceutical Preparations and Excipients, Key Laboratory of Medicinal Chemistry and Molecular Diagnosis of the Ministry of Education, Key Laboratory of Chemical Biology of Hebei Province, College of Chemistry and Materials Science, Hebei University, Baoding, Hebei 071002, P. R. China.
None:
An efficient cascade nitration-annulation-rearrangement of indole-tethered 1,6-enynes, tert-butyl nitrite (TBN) with O2 was developed for the synthesis of various NO2-dicarbonyl substituted pyrrolo[1,2-a]indole derivatives. This radical cascade process selected O2 as the carbonyl oxygen source and low-cost TBN as the nitro reagent. Meanwhile, the stable indole skeleton could smoothly undergo rearrangement to access dicarbonyl fused cycles. In addition, complex molecular transformation and scaled-up experiments examined the application of this tandem system. Finally, diverse mechanistic studies (including isotopic labeling, radical inhibition/capturation experiments) explored the reaction pathway.
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