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Synlett
Volumn , Issue 20, 2008, Pages 3157-3162
A new approach to 3-substituted indoles through palladium-catalyzed C-H activation followed by intramolecular amination reaction of enamines
Author keywords

Animations; C H activation; Catalysis; Indoles; Palladium
Indexed keywords

EID: 58149386276     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-0028-1087413     Document Type: Article
Times cited : (54)
References (43)
  • 1
    • 34547095509 scopus 로고    scopus 로고
    • For selected recent reviews, see: a
    • For selected recent reviews, see: (a) Higuchi, K.; Kawasaki, T. Nat. Prod. Rep. 2007, 24, 843.
    • (2007) Nat. Prod. Rep , vol.24 , pp. 843
    • Higuchi, K.1    Kawasaki, T.2
  • 7
    • 51049114031 scopus 로고    scopus 로고
    • For selected recent reviews, see: a
    • For selected recent reviews, see: (a) Patil, N. T.; Yamamoto, Y. Chem. Rev. 2008, 108, 3395.
    • (2008) Chem. Rev , vol.108 , pp. 3395
    • Patil, N.T.1    Yamamoto, Y.2
  • 30
    • 33846643450 scopus 로고    scopus 로고
    • 2 was previously reported, see: (a) Queiroz, M.-J. R. P.; Abreu, A. S.; Castanheira, E. M. S.; Ferreira, P. M. T. Tetrahedron 2007, 63, 2215.
    • 2 was previously reported, see: (a) Queiroz, M.-J. R. P.; Abreu, A. S.; Castanheira, E. M. S.; Ferreira, P. M. T. Tetrahedron 2007, 63, 2215.
  • 34
    • 27144450136 scopus 로고    scopus 로고
    • Only a few examples of Pd-catalyzed C-H amination have been reported to date, see: a
    • Only a few examples of Pd-catalyzed C-H amination have been reported to date, see: (a) Tsang, W. C. P.; Zheng, N.; Buchwald, S. L. J. Am. Chem. Soc. 2005, 127, 14560.
    • (2005) J. Am. Chem. Soc , vol.127 , pp. 14560
    • Tsang, W.C.P.1    Zheng, N.2    Buchwald, S.L.3
  • 36
    • 34547227201 scopus 로고    scopus 로고
    • We have already reported the synthesis of indazoles using a Pd-catalyzed intramolecular C-H amination process, see: Inamoto, K, Saito, T, Katsuno, M, Sakamoto, T, Hiroya, K. Org. Lett. 2007, 9, 2931
    • We have already reported the synthesis of indazoles using a Pd-catalyzed intramolecular C-H amination process, see: Inamoto, K.; Saito, T.; Katsuno, M.; Sakamoto, T.; Hiroya, K. Org. Lett. 2007, 9, 2931.
  • 38
    • 58149379361 scopus 로고    scopus 로고
    • Use of solvents such as DMF, NMP, MeCN, dioxane, toluene, and DCE resulted in decreased yields
    • Use of solvents such as DMF, NMP, MeCN, dioxane, toluene, and DCE resulted in decreased yields.
  • 39
    • 58149383603 scopus 로고    scopus 로고
    • We also examined the effect of a variety of additives such as phosphines, N-heterocyclic carbenes, tetraalkylammonium salts, inorganic bases, lithium and silver salts, and so on, all of which led to unsatisfactory results
    • We also examined the effect of a variety of additives such as phosphines, N-heterocyclic carbenes, tetraalkylammonium salts, inorganic bases, lithium and silver salts, and so on, all of which led to unsatisfactory results.
  • 40
    • 58149395999 scopus 로고    scopus 로고
    • Typical Procedure for the Pd-Catafyzed C-H Amination of Enamines (Table 1, entry 9) A mixture of 1 (50.0 mg, 0.14 mmol, Pd(OAc) 2 (3.2 mg, 0.014 mmol, and Cu(OAc)2 (26.0 mg, 0.14 mmol) in DMSO (2.9 mL) was stirred at 80°C for 24 h. The reaction mixture was extracted with EtOAc (3 x 5 mL) and the combined organic layer was washed with brine (10 mL, and dried over MgSO4. The solvent was evaporated and the residue was purified by silica gel column chromatography (hexane-EtOAc, 9:1) to give indole 2 (26.2 mg, 53, as a colorless solid. 1-(4- Methylphenylsulfonyl)-3-phenylindole (2) Mp 151-152°C (colorless needles from hexane-EtOAc, IR (film, 2924, 1597, 1447, 1371, 1175, 669 cm -1. 1H NMR (400 MHz, CDCl3, δ, 2.34 (3 H, s, 7.22 (2 H, d, J, 8.2 Hz, 7.26-7.30 (1 H, m, 7.34-7.38 (2 H, m, 7.46 (2 H, t, J, 7.8 Hz, 7.59-7.61 (2 H, m, 7.69 (1 H, s, 7.77 1 H, d, J
    • 2S: C, 72.60; H, 4.93; N, 4.03. Found C, 72.63; H, 5.08; N, 3.99.
  • 41
    • 58149391119 scopus 로고    scopus 로고
    • Typical Procedure for the Synthesis of Enol Ether (4a, Table 2, entry 1) To a solution of(methoxymethyl)triphenylphosphinium chloride (1.1 g, 3.1 mmol) in anhyd dioxane (5 mL) was slowly added BuLi (1.53 M solution in hexane, 2.3 mL, 3.1 mmol) at 0°C and stirred for 30 min at the same temperature. A solution of 3a (0.50 g, 2.1 mmol) in anhyd dioxane (10 mL) was then slowly added at 0°C, and the mixture was heated under reflux for 10 h. The reaction mixture was treated with sat. aq NH4Cl soin (5 mL, and the aqueous phase was extracted with EtOAc (3 x 10 mL, The combined organic layer was washed with brine (5 mL) and dried over MgSO4. The solvent was evaporated, and the residue was purified by silica gel column chromatography (hexane-EtOAc, 9:1) to give 4a (0.4 g, 67, as a colorless oil. 1,1-Bis(4-methoxyphenyl)-2-methoxyethene (4a) IR (film, 2359, 1341, 1508, 1244 cm-1. 1H NMR 400 MHZ, CDCl3
    • 3): δ = 2.44 (3 H, s), 3.77 (3 H, s), 3.82 (3 H, s), 6.22 (1 H, d, J = 11.4 Hz), 6.65 (1 H, d, J = 11.4 Hz)
  • 42
    • 58149396026 scopus 로고    scopus 로고
    • Geometry of enamine 5f was determined by NOESY.
    • Geometry of enamine 5f was determined by NOESY.
  • 43
    • 58149392319 scopus 로고    scopus 로고
    • 1H NMR spectroscopy.
    • 1H NMR spectroscopy.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.