2007
DOI: 10.1021/jo070547x
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Assembly of Conjugated Enynes and Substituted Indoles via CuI/Amino Acid-Catalyzed Coupling of 1-Alkynes with Vinyl Iodides and 2-Bromotrifluoroacetanilides

Abstract: 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 K(2)CO(3) 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 orth… Show more

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Cited by 187 publications
(54 citation statements)
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“…According to the optimal reaction conditions reported by our group, 24) all experiments were performed with 2.0 eq of acetylene, 0.8 eq of an additive, 20 mol% of copper salt, and 200 eq of pyridine in N,NЈ-dimethylformamide (DMF) at 80°C. 32) However, bidentate ligands such as trans-N,NЈ-dimethylcyclohexane-1,2-diamine, 2,2Ј-bipyridine, L-proline, and 1,10-phenanthroline, which are typically used in copper-mediated coupling reactions, 25,26) were ineffective in promoting the reaction (Table 1, entries 3-6). In contrast, most inorganic bases proved applicable and furnished the cyclized product 4aa in 13-63% yields with K 2 CO 3 being suitable ( To determine the optimal copper salts, reactions with various copper(I) (CuI, CuBr, and CuOTf) and copper(II) salts (CuO, CuBr 2 , and CuCl 2 ) 33) were examined.…”
Section: Resultsmentioning
confidence: 99%
See 1 more Smart Citation
“…According to the optimal reaction conditions reported by our group, 24) all experiments were performed with 2.0 eq of acetylene, 0.8 eq of an additive, 20 mol% of copper salt, and 200 eq of pyridine in N,NЈ-dimethylformamide (DMF) at 80°C. 32) However, bidentate ligands such as trans-N,NЈ-dimethylcyclohexane-1,2-diamine, 2,2Ј-bipyridine, L-proline, and 1,10-phenanthroline, which are typically used in copper-mediated coupling reactions, 25,26) were ineffective in promoting the reaction (Table 1, entries 3-6). In contrast, most inorganic bases proved applicable and furnished the cyclized product 4aa in 13-63% yields with K 2 CO 3 being suitable ( To determine the optimal copper salts, reactions with various copper(I) (CuI, CuBr, and CuOTf) and copper(II) salts (CuO, CuBr 2 , and CuCl 2 ) 33) were examined.…”
Section: Resultsmentioning
confidence: 99%
“…According to the reported methods typically used for indole syntheses, we tested the reactions using a catalytic amount of copper(I) salts with bidentate ligands such as bipyridine, 1,10-phenanthroline, and trans-N,NЈ-dimethylcyclohexane-1,2-diamine. [25][26][27] However, no coupling reactions were observed, and degradation of the starting naphthoquinone to a dehalogenated compound gradually occurred during the reaction.…”
mentioning
confidence: 99%
“…Since Miura and co-workers reported that CuI/PPh 3 catalyzed cross-couplings of aryl iodides and terminal alkynes, [13] much attention has been focused on the use of copper complexes as the catalysts for the Sonogashira cross-coupling for copper is less toxic and far more economic than palladium. [14][15][16][17][18][19][20][21] Although copper-based catalysts have been proposed as an alternative to palladium-based catalysts for Sonogashira couplings, these catalyst systems generally require high copper loadings to maintain a catalytic cycle. Therefore, the development of an efficient reaction system with recyclable copper catalysts is highly desirable.…”
Section: Introductionmentioning
confidence: 99%
“…3,4 Popular approaches to these heterocycles include N-modification of 2-substituted NH indoles, 5-7 2-arylation of N-substituted indoles, [8][9][10] coupling/annulation of o-haloanilines with alkynes, [11][12][13] and intramolecular cyclization of o-(gem-dihalovinyl)anilines. [14][15][16] Several one-pot synthetic protocols have also been developed recently.…”
Section: Introductionmentioning
confidence: 99%