American Chemical Society
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Synthesis of 3‑(Organochalcogen) Chalcogenazolo Indoles via Cascade Cyclization of N‑Alkynylindoles

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journal contribution
posted on 2019-01-31, 00:00 authored by Thaís Prochnow, Adriano Maroneze, Davi Fernando Back, Gilson Zeni
A transition metal-free one-pot, three-steps protocol combining N-alkynylindoles, n-butyllithium, elemental selenium, and an electrophile source was developed to allow the synthesis of 3-(organoselanyl) selenazolo indoles. Substrate scope was studied by varying the structure of N-alkynylindoles and the electrophile source. This sequential reaction proceeded selectively through an initial intramolecular 5-endo-dig mode with two new carbon–selenium bonds formation in a one-pot procedure. The reaction conditions were also compatible with elemental sulfur and tellurium, which led to construct 3-(alkylthio) thiazolo indoles and 3-(alkyltelluro) tellurazolo indoles, respectively. In addition, it was also demonstrated that a series of dichalcogenides derived from chalcogenazoloindoles ring could be easily prepared via oxidation of chalcogenolate anion in contact with air.