Publication Date:
2015-09-18
Description:
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. Beilstein J. Org. Chem. 2015, 11, 1649–1655. doi:10.3762/bjoc.11.181
Keywords:
ene-sulfonamideimineradical cyclizationradical fragmentationspiro-indoles
Electronic ISSN:
1860-5397
Topics:
Chemistry and Pharmacology
Permalink