Sc(OTf)3-Catalyzed Oligomerization of Indole: One-Pot Synthesis of 2-[2,2-Bis(indol-3-yl)ethyl]anilines and 3-(Indolin-2-yl)indoles

Shelke, Ganesh M.; Kumar, Anil

doi:10.1055/s-0036-1588181

Cited by 13 publications

(3 citation statements)

References 9 publications

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“…Regarding the limitations of this transformation, 5‐nitroindole did not yield the target product 61 , reacting with itself following an oligomerization process [29] . The reaction is also not compatible with furan and thiophene derivatives, which decomposed under the reaction conditions.…”

Section: Resultsmentioning

confidence: 96%

Synthesis of Unprotected β‐Arylethylamines by Iron(II)‐Catalyzed 1,2‐Aminoarylation of Alkenes in Hexafluoroisopropanol

et al. 2023

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β-Arylethylamines are prevalent structural motifs in molecules exhibiting biological activity. Here we report a sequential one-pot protocol for the 1,2aminoarylation of alkenes with hydroxylammonium triflate salts and (hetero)arenes. Unlike existing methods, this reaction provides a direct entry to unprotected β-arylethylamines with remarkable functional group tolerance, allowing key drug-oriented functional groups to be installed in a two-step process. The use of hexafluoroisopropanol as a solvent in combination with an iron(II) catalyst proved essential to reaching highvalue nitrogen-containing molecules.

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Section: Resultsmentioning

confidence: 96%

Synthesis of Unprotected β‐Arylethylamines by Iron(II)‐Catalyzed 1,2‐Aminoarylation of Alkenes in Hexafluoroisopropanol

et al. 2023

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“…Thus, the reaction was investigated using AlCl 3 in MeCN or EtOH (entries 3 and 4). Initially, the desired product 5 was not obtained, and partial decomposition of substrate 7 was observed; however, bis-indole 15 was generated via the acid-mediated trimerization of 6-bromoindole (42% yield, based on 6-bromoindole, for entry 4) . The structure of 15 was unambiguously determined by X-ray crystallographic analysis (see Supporting Information (SI)).…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis and Antibacterial Activity of Marine Tris-indole Alkaloid Tulongicin A

Tsuruda,

Sato,

Aoyama

et al. 2024

J. Nat. Prod.

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Bis-indole alkaloids from marine sponges are an intriguing class of natural products with a variety of activities. However, only a preliminary biological study of tulongicin A (5), a related previously isolated marine tris-indole alkaloid, has been conducted. In this study, we accomplished the first asymmetric total synthesis of 5 via the construction of an imidazoline-linked bisindolylmethane skeleton using a Friedel−Crafts-type reaction. Our synthesis enabled a detailed study of the antibacterial profile of 5. Compound 5 displayed bactericidal activity against Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA) strains.

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“…Since then, various alternative acids have been applied including protic acids, such as silica-bonded S-sulfonic acid [ 13 ], polyvinylsulfonic acid (PVSA) [ 14 ], kaolin-supported H 2 SO 4 [ 15 ], polyvinylpolypyrrolidone-supported triflic acid (PVPP . OTf) [ 16 ], ascorbic acid [ 17 ], phosphoric acid [ 18 ], benzenesulfonic acid [ 19 ], chitosan–SO 3 H (CTSA) [ 20 ], phthalimide- N -sulfonic acid (PISA) [ 21 ] and SiO 2 -KHSO 4 [ 22 ] as well as Lewis acids, such as FeCl 3 [ 23 – 24 ], RuCl 3 ·3H 2 O [ 25 ], AgNO 3 [ 26 ], glycerol and [Fe(III)-(salen)]Cl [ 27 ], Fe(DS) 3 · n H 2 O [ 28 ], Sc(OTf) 3 [ 29 ], B(C 6 F 5 ) 3 or PhSiCl 3 [ 30 ] and Cp 2 TiCl 2 [ 31 ]. However, most of these reactions face some serious drawbacks, such as the requirement of large quantities of the catalyst due to present moisture or formation of adducts with the substrate, long reaction times, lower yields, and production of large amounts of toxic waste during work-up.…”

Section: Reviewmentioning

confidence: 99%

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

Kolagkis,

Galathri,

Kokotos

2024

Beilstein J. Org. Chem.

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The synthesis of indoles and their derivatives, more specifically bis(indolyl)methanes (BIMs), has been an area of great interest in organic chemistry, since these compounds exhibit a range of interesting biological and pharmacological properties. BIMs are naturally found in cruciferous vegetables and have been shown to be effective antifungal, antibacterial, anti-inflammatory, and even anticancer agents. Traditionally, the synthesis of BIMs has been achieved upon the acidic condensation of an aldehyde with indole, utilizing a variety of protic or Lewis acids. However, due to the increased environmental awareness of our society, the focus has shifted towards the development of greener synthetic technologies, like photocatalysis, organocatalysis, the use of nanocatalysts, microwave irradiation, ball milling, continuous flow, and many more. Thus, in this review, we summarize the medicinal properties of BIMs and the developed BIM synthetic protocols, utilizing the reaction between aldehydes with indoles, while focusing on the more environmentally friendly methods developed over the years.

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Sc(OTf)3-Catalyzed Oligomerization of Indole: One-Pot Synthesis of 2-[2,2-Bis(indol-3-yl)ethyl]anilines and 3-(Indolin-2-yl)indoles

Cited by 13 publications

References 9 publications

Synthesis of Unprotected β‐Arylethylamines by Iron(II)‐Catalyzed 1,2‐Aminoarylation of Alkenes in Hexafluoroisopropanol

Synthesis of Unprotected β‐Arylethylamines by Iron(II)‐Catalyzed 1,2‐Aminoarylation of Alkenes in Hexafluoroisopropanol

Total Synthesis and Antibacterial Activity of Marine Tris-indole Alkaloid Tulongicin A

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

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