Synthesis of highly substituted indolines and indoles via intramolecular [4 + 2] cycloaddition of ynamides and conjugated enynes.

ABSTRACT: Ynamides react with conjugated enynes in intramolecular [4 + 2] cycloadditions to afford substituted indolines that undergo oxidation with o-chloranil to furnish the corresponding indoles. The cycloaddition substrates are easily assembled from derivatives of 3-butynylamine by Sonogashira coupling with alkenyl halides followed by copper-catalyzed N-alkynylation with acetylenic bromides. Diynamides participate as particularly reactive 2pi components in the cycloaddition, providing access to indolines with carbon substituents at the C-7 position. Enynamides serve as 4pi components in a complementary version of the cycloaddition strategy which provides access to indoles and indolines substituted with carbon substituents at C-4. These enyne cycloadditions take place upon heating the substrates

SUBMITTER: Dunetz JR 

PROVIDER: S-EPMC2893034 | biostudies-literature | 2005 Apr

REPOSITORIES: biostudies-literature