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Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

Two new fates of imine intermediates formed on radical cyclizations of ene-sulfonamides have been identified, reduction and hydration/fragmentation. Tin hydride-mediated cyclizations of 2-halo-N-(3-methyl-N-sulfonylindole)anilines provide spiro[indoline-3,3'-indolones] or spiro-3,3'-biindo...

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Detalles Bibliográficos
Autores principales: Zhang, Hanmo, Hay, E Ben, Geib, Stephen J, Curran, Dennis P
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Beilstein-Institut 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4660904/
https://www.ncbi.nlm.nih.gov/pubmed/26664585
http://dx.doi.org/10.3762/bjoc.11.181
Descripción
Sumario:Two new fates of imine intermediates formed on radical cyclizations of ene-sulfonamides have been identified, reduction and hydration/fragmentation. Tin hydride-mediated cyclizations of 2-halo-N-(3-methyl-N-sulfonylindole)anilines provide spiro[indoline-3,3'-indolones] or spiro-3,3'-biindolines (derived from imine reduction), depending on the indole C2 substituent. Cyclizations of 2-haloanilide derivatives of 3-carboxy-N-sulfonyl-2,3-dihydropyrroles also presumably form spiro-imines as primary products. However, the lactam carbonyl group facilitates the ring-opening of these cyclic imines by a new pathway of hydration and retro-Claisen-type reaction, providing rearranged 2-(2'-formamidoethyl)oxindoles.