Assembly of Conjugated Enynes and Substituted Indoles via CuI/Amino Acid-Catalyzed Coupling of 1-Alkynes with Vinyl Iodides and 2-Bromotrifluoroacetanilides
作者:Feng Liu、Dawei Ma
DOI:10.1021/jo070547x
日期:2007.6.1
Cross-coupling of 1-alkynes with vinyl iodides occurs at 80 degrees C in dioxane catalyzed by CuI/N,N-dimethylglycine to afford conjugated enynes in good to excellent yields. Heating a mixture of 2-bromotrifluoroacetanilide, 1-alkyne, 2 mol % of CuI, 6 mol % of L-proline, and K2CO3 in DMF at 80 degrees C leads to the formation of the corresponding indole. This conversion involves a CuI/L-proline-catalyzed coupling between aryl bromide and the 1-alkyne followed by a CuI-mediated cyclization process. An ortho-substituent effect directed by NHCOCF3 enables the reaction to proceed under these mild conditions. Both aryl acetylenes and O-protected propargyl alcohol can be applied, leading to 5-, 6-, or 7-substituted 2-aryl and protected 2-hydroxymethyl indoles in good yields. With simple aliphatic alkynes, however, lower yields were observed.
Synthesis of 2-substituted indoles by palladium-catalyzed heteroannulation with Pd–NaY zeolite catalysts
作者:Ki Bum Hong、Chul Wee Lee、Eul Kgun Yum
DOI:10.1016/j.tetlet.2003.11.075
日期:2004.1
Various 2-substitutedindoles were prepared by heteroannulation of o-iodoanilines and terminal alkynes in a one-pot reaction with a Pd(II)–NaY zeolite catalyst. The product formation largely depended on the solvent, base, and reaction temperature. The recycled catalyst showed good reusability in the heteroannulation reaction.