Synthesis of highly substituted indolines and indoles via intramolecular [4+2] cycloaddition of ynamides and conjugated enynes
Synthesis of highly substituted indolines and indoles via intramolecular [4+2] cycloaddition of ynamides and conjugated enynes
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DOI：
10.1021/ja051180l
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发表时间：
2005-04-27
影响因子：
15
通讯作者：
Danheiser, RL
中科院分区：
文献类型：
--
作者：
Dunetz, JR;Danheiser, RL
Ynamides react with conjugated enynes in intramolecular [4 + 2] cycloadditions to afford substituted indolines that undergo oxidation witho-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 2π components in the cycloaddition, providing access to indolines with carbon substituents at the C-7 position. Enynamides serve as 4π 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 at 110−210 °C in toluene or 2,2,2-trifluoroethanol and in some cases can be achieved at 0 °C to room temperature in the presence of Lewis acids such as Me2AlCl.
