The cascade amination/cyclization of N‐arylacrylamides with alkyl amines under visible‐light photoredox catalysis is realized via intermediacy of aminium radicals. The aminium radicals are generated by a two‐step sequence which involves N‐chlorination of alkyl amines and subsequent reductive N−Cl cleavage. This method provides a convenient access to aminated oxindoles.magnified image
A diphenyl-diselenide-mediated Claisen-type rearrangement/cyclization of propargylic aryl ethers under metal-free conditions is developed, affording various naphthofuran-2-carboxaldehydes in moderate to excellent yield. The broad substrate scope and excellent functional group compatibility suggest that it can be a straightforward and powerful method to access naphthofuran-2-carboxaldehydes in a highly regioselective manner. Moreover, this reaction can be scaled up to the gram scale.
The annulation reactions of benzoamidyl radicals with alkenes were realized under visible light irradiation with fac-Ir(ppy) 3 as catalyst and N-aminopyridinium salts as benzoamidyl radical precursors. The reaction can deliver two distinct types of products: in the case of vinyl arenes, [3 + 2] annulation product dihydrooxazoles were yielded exclusively; when alkyl-substituted alkenes were used, on the other hand, it afforded [4 + 2] annulation product dihydroisoquinolinones. Factors determining the reaction consequence were elucidated by DFT calculations.
A visible-light-promoted intermolecular radical amidation/cyclization of arylacrylamides was realized by using N-aminopyridinium salts as the source of primary amidyl radicals. The reaction exhibits a broad scope and good functionality tolerance,...
An approach for the preparation of boronated γ-lactams via palladium-catalyzed boryldifluoroalkylation of alkenes with α-bromodifluoroacetamides was developed. This method exhibits good functional group tolerance. Various boronated products were obtained in moderate to good yields for 1 h. Mechanistic studies indicated that this reaction may involve an intramolecular radical cascade cyclization process.
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