Catalyst-free aqueous-mediated conjugative addition of indoles to β-nitrostyrenes

Habib, Pateliya Mujjamil; Kavala, Veerababurao; Kuo, Chun Wei; Yao, Ching Fa

doi:10.1016/j.tetlet.2008.09.109

Cited by 57 publications

(14 citation statements)

References 37 publications

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“…The required starting materials 3a–3h were prepared from corresponding 2‐arylindoles and β‐nitrostyrenes according to the reported methods (see Appendix S1, Supporting information) 6a–g . As reported in our previous paper, 5a the reaction of 3a was examined in EtOH (reflux, 24 h) in the presence of Mn(OAc) 3 (4.0 equiv).…”

Section: Methodssupporting

confidence: 80%

Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)₃‐mediated Cyclization

Kim

Lim

Min

et al. 2016

Bulletin Korean Chem Soc

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Diversely substituted benzo [a]carbazoles and related derivatives are important because of their interesting biological activities such as neuroprotective property, antitumor activity, and kinase inhibitory activity. 1 Thus, various synthetic methods have been developed 2 including Lewis acidcatalyzed annulation of 2-arylindoles with propargylic alcohol derivatives, 2a,b double cascade cyclization of diynes catalyzed by gold, 2c-e iodine, 2f or palladium, 2g and coppercatalyzed synthesis via α-C-arylation of ketones. 2h Recently, we also reported the synthesis of benzo[a]carbazoles from 2-arylindoles via sequential propargylation, propargyl-allenyl isomerization, and 6π-electrocyclization approach, as shown in Scheme 1. 3 Various 5-benzyl-and 5-methylbenzo[a]carbazoles have been synthesized; however, 5-unsubstituted benzo[a]carbazoles could not be synthesized by the approach. 3 In order to develop a synthetic method of 5-unsubstituted benzo[a]carbazoles, we decided to examine the reaction of β-(2-phenylindolyl) nitroalkane 3a by Mn(OAc) 3 -mediated cyclization and subsequent elimination of nitrous acid, 4,5 as shown in Scheme 1. A similar synthesis of a naphthalene ring via Mn(OAc) 3mediated intramolecular oxidative coupling reaction between arene and nitroalkane moieties has already been reported in the previous studies. 5a The required starting materials 3a-3h were prepared from corresponding 2-arylindoles and β-nitrostyrenes according to the reported methods (see Appendix S1, Supporting information). 6a-g As reported in our previous paper, 5a the reaction of 3a was examined in EtOH (reflux, 24 h) in the presence of Mn(OAc) 3 (4.0 equiv). To our delight, 4a was obtained in a reasonable yield (56%) along with a low yield of 5-nitro derivative 5a (13%). The reactions in other solvents such as MeOH, n-propanol, n-butanol, and polyethylene glycol (PEG)-3400/ t BuOH were less effective when compared with EtOH. The reaction in AcOH showed the formation of many intractable side products. The use of CAN (cerium ammonium nitrate) in EtOH was completely ineffective. When we used lesser amount of Mn(OAc) 3 (3.0 equiv) in EtOH (reflux, 24 h), the yields of 4a (48%) and 5a (8%) decreased a little.The synthesis of various benzo[a]carbazoles was carried out under the typical reaction condition, and the results

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Section: Methodssupporting

confidence: 80%

Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)₃‐mediated Cyclization

Kim

Lim

Min

et al. 2016

Bulletin Korean Chem Soc

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“…The solvent was removed under reduced pressure and the crude residue was purified by flash chromatography on silica gel to afford pure product. The references of the known compounds are: 2a [ 14 , 15 , 17 , 19 ], 2b [ 36 ], 2c [ 15 , 22 ], 2d [ 13 , 15 , 17 ], 2e [ 36 ], 2f [ 36 ], 2g [ 22 ], 2j [ 15 , 22 ], 2k [ 15 , 36 ], cis- 2n [ 14 ], trans- 2n [ 14 ], 4a [ 15 , 17 , 19 ], 4b [ 15 , 17 ], 4c [ 12 , 36 ], 4d [ 15 ], 4e [ 14 , 17 ], 4f [ 14 ], 4g [ 17 , 19 ], 4k [ 15 , 35 ], 4l [ 45 ], 5 [ 46 ].…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we have reported synthesis of 1,5-benzodiazepine derivatives catalyzed by NBS under mild conditions [ 34 ]. In continuation of our research work on nitroolefins [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ], we have developed a new route for the synthesis of 3-alkylated indoles via Friedel-Crafts alkylation of indole with β-nitrostyrene, catalyzed by N -bromosuccinimide.…”

Section: Introductionmentioning

confidence: 99%

An Efficient Method for the N-Bromosuccinimide Catalyzed Synthesis of Indolyl-Nitroalkanes

Kuo

Wang

et al. 2009

Molecules

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An efficient and practical method for the synthesis of indolyl-nitroalkane derivatives catalyzed by N-bromosuccinimide is described. The generality of this method was demonstrated by synthesizing an array of diverse 3-substituted indole derivatives by the reaction of different β-nitrostyrenes with various substituted indoles. Simple reaction conditions accompanied by good yields of indolyl-nitroalkanes are the merits of this methodology.

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“…However, these catalysts still appeared to have several shortcomings, for example, toxicity of metal salts. Recently, catalyst‐free Michael addition of nitrostyrene with indole was developed [31, 32]. However, the reaction required higher temperature and use benzene or water as the solvent [31, 32].…”

Section: Introductionmentioning

confidence: 99%

An efficient and clean Michael addition of indoles to electron‐deficient olefins under solvent‐ and catalyst‐free condition

Liu

Duan

Zhang

2010

Journal of Heterocyclic Chem

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An efficient Michael addition of indoles to electron‐deficient olefins under solvent‐ and catalyst‐free condition afforded biologically important 3‐substituted indole derivatives in good to excellent yields was reported. The acidic NH proton of indole plays a key role in Michael addition of indoles to electron‐deficient olefins. This very simple procedure provides an efficient and clean process for the synthesis of indole derivatives. J. Heterocyclic Chem., (2011).

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Catalyst-free aqueous-mediated conjugative addition of indoles to β-nitrostyrenes

Cited by 57 publications

References 37 publications

Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)₃‐mediated Cyclization

Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)₃‐mediated Cyclization

An Efficient Method for the N-Bromosuccinimide Catalyzed Synthesis of Indolyl-Nitroalkanes

An efficient and clean Michael addition of indoles to electron‐deficient olefins under solvent‐ and catalyst‐free condition

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Catalyst-free aqueous-mediated conjugative addition of indoles to β-nitrostyrenes

Cited by 57 publications

References 37 publications

Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)3‐mediated Cyclization

Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)3‐mediated Cyclization

An Efficient Method for the N-Bromosuccinimide Catalyzed Synthesis of Indolyl-Nitroalkanes

An efficient and clean Michael addition of indoles to electron‐deficient olefins under solvent‐ and catalyst‐free condition

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Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)₃‐mediated Cyclization

Synthesis of Benzo[a]carbazole Derivatives from β‐(2‐Arylindolyl)nitroalkanes via Mn(OAc)₃‐mediated Cyclization