100723-77-1Relevant articles and documents
Efficient preparation of polyfunctional indoles via a zinc organometallic variation of the Fischer indole synthesis
Zhang, Zhi-Guang,Haag, Benjamin A.,Li, Jin-Shan,Knochel, Paul
, p. 23 - 29 (2011)
Functionalized organozinc reagents readily react with various aryldiazonium salts furnishing regioselectively polyfunctional indoles after heating with microwave irradiation. This new organometallic variation of the Fischer indole synthesis tolerates a wide range of functional groups and can be readily scaled up. Georg Thieme Verlag Stuttgart · New York.
A Convenient Modification of the Fischer Indole Synthesis with a Solid Acid
Chandrasekhar, Sosale,Mukherjee, Somnath
, p. 1018 - 1022 (2015)
(Chemical Equation Presented). A new one-pot version of the titled reaction involves heating a mixture of a carbonyl compound, a phenylhydrazine, and the cation exchange resin Amberlite IR 120 in refluxing ethanol. A variety of enolizable aldehydes, and ketones and several substituted phenylhydrazines could thus be converted to the corresponding indoles in excellent yields (70-88%). Reaction times were typically 6-10 h, with the resin being then filtered off and the product isolated after minimal workup.
Mechanism of Fischer Reaction. Dependence of Thermal Indolization of Cyclohexanone Arylhydrazones on Nature of Substituent in the Benzene Ring
Przheval'skii, N. M.,Kostromina, L. Yu.,Grandberg, I. I.
, p. 154 - 158 (1988)
The kinetics of the Fischer thermal indolization of monosubstituted cyclohexanone arylhydrazones was studied by the spectrophotometric method.The enthalpy and entropy of activation of the reaction were calculated.The data obtained were interpreted in terms of a consistent mechanism of formation of a carbon-carbon bond (the -sigmatropic shift).It was found that the influence of the electronic factors on the rate of the sigmatropic rearrangement is inappreciable.
Fischer indole synthesis with organozinc reagents
Haag, Benjamin A.,Zhang, Zhi-Guang,Li, Jin-Shan,Knochel, Paul
, p. 9513 - 9516 (2010)
Updated classic: Primary and secondary alkylzinc reagents add to various aryldiazonium salts leading regioselectively to polyfunctional indoles by means of a [3,3]-sigmatropic shift and subsequent aromatization. This organometallic variation of the Fischer indole synthesis tolerates a wide range of functional groups and displays absolute regioselectivity. Copyright
Copper(II) catalyzed aromatization of tetrahydrocarbazole: An unprecedented protocol and its utility towards the synthesis of carbazole alkaloids
Dalvi, Bhakti A.,Lokhande, Pradeep D.
, p. 2145 - 2149 (2018)
An efficient protocol for the aromatization of tetrahydrocarbazole is described by using catalytic copper(II) chloride dihydrate in DMSO. This newly established methodology has utilized towards the synthesis of naturally occurring carbazole alkaloids, namely 3-methylcarbazole, 3-formyl carbazole, glycozoline, glycozolicine and clauszoline-K. In addition, the protocol is generalized for the aromatization of N-substituted tetrahydrocarbazole, 1,2,3,4-tetrahydroquinoline, 1,2,3,4-tetrahydroisoquinoline and 1,2,3,4-tetrahydro β-carboline to give the corresponding heteroaromatic compounds from very good to excellent yield. Moreover, this method has been proven to be tolerant to a broad range of functional groups with excellent yields.
Annulation of Indoles with 1,n-Dibromoalkanes by a Pd(II)-Catalyzed and Norbornene-Mediated Reaction Cascade
Bach, Thorsten,Henkel, Michael
, p. 1231 - 1238 (2020)
Employing 1,3-dibromopropane, 1,4-dibromobutane, and 1,5-dibromopentane as biselectrophiles, the annulation of indoles was probed in the presence of PdCl 2 (MeCN) 2 as a catalyst and norbornene as a transpositional ligand. Ring formation to a five-membered ring was observed at positions C2 and N, while annulation of a six-membered ring occurred at positions C2 and C3. The latter cascade process was successfully applied to the direct synthesis of 1,2,3,4-tetrahydrocarbazoles from indoles (11 examples, 31-68% yield). Seven-membered-ring annulation was feasible by an initial coupling at positon C2 followed by alkylation at C3.
N, N -Dimethylpyridin-4-amine (DMAP) based ionic liquids: Evaluation of physical properties via molecular dynamics simulations and application as a catalyst for Fisher indole and 1 H -tetrazole synthesis
Ghumro, Sarfaraz Ali,Saleem, Sana,Al-Rashida, Mariya,Iqbal, Nafees,Alharthy, Rima D.,Ahmed, Shakil,Moin, Syed Tarique,Hameed, Abdul
, p. 34197 - 34207 (2017)
The last few decades have seen a rapid increase in the use of ionic liquids (ILs) as a green alternative to traditional solvents in organic synthesis. The use of ILs as catalysts has also increased in recent years. Herein we the report synthesis of new N,N-dimethylpyridin-4-amine (DMAP) based ionic liquids (ILs) as new and efficient catalysts for the facile synthesis of indoles (via Fischer indole synthesis), and 1H-tetrazoles (via click chemistry). The method is environmentally friendly, requiring only minimum catalyst loading (0.2 equiv. for Fischer indole synthesis). In the case of 1H-tetrazole formation (via click chemistry), the reaction was carried out under a solvent free environment. Moreover, thermal studies (TGA, DTG and DSC) of DMAP-ILs (2, 3) have also been carried out to elicit their stability for temperature dependent reactions. Application of molecular dynamics simulations provided valuable insights into the structural and transport properties of these ionic liquids. An MP2 method was applied to evaluate the stability of the compound via binding energy calculations.
Process for synthesizing [b]-cycloindole derivatives
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Paragraph 0039-0041, (2021/04/17)
The invention discloses a method for synthesizing [b]-cyclized indole derivatives. The method comprises the steps as follows: alkylation ring-closing domino reactions at C2 and C3 sites of indole aresequentially realized with a one-pot process under the action of alkali and a palladium catalyst with norbornene as a transient guide medium and dihaloalkane as an alkylation reagent, and the [b]-cyclized indole derivatives are effectively synthesized. The method has mild conditions, commercially available indole is directly used as a substrate, a pre-functionalization process is omitted, reactionsteps are reduced, the atom economy is higher, simple indole micromolecular structures are modified, and the [b]-cyclized indole derivatives can be further applied to medicine or total synthesis research and the like and have higher potential value and broad application prospects in medicinal chemistry and other fields.
Direct Synthesis of Indoles from Azoarenes and Ketones with Bis(neopentylglycolato)diboron Using 4,4′-Bipyridyl as an Organocatalyst
Misal Castro, Luis C.,Sultan, Ibrahim,Nishi, Kohei,Tsurugi, Hayato,Mashima, Kazushi
, p. 3287 - 3299 (2021/03/01)
Multifunctionalized indole derivatives were prepared by reducing azoarenes in the presence of ketones and bis(neopentylglycolato)diboron (B2nep2) with a catalytic amount of 4,4′-bipyridyl under neutral reaction conditions, where 4,4′-bipyridyl acted as an organocatalyst to activate the B-B bond of B2nep2 and form N,N′-diboryl-1,2-diarylhydrazines as key intermediates. Further reaction of N,N′-diboryl-1,2-diarylhydrazines with ketones afforded N-vinyl-1,2-diarylhydrazines, which rearranged to the corresponding indoles via the Fischer indole mechanism. This organocatalytic system was applied to diverse alkyl cyclic ketones, dialkyl, and alkyl/aryl ketones, including heteroatoms. Methyl alkyl ketones gave the corresponding 2-methyl-3-substituted indoles in a regioselective manner. This protocol allowed us to expand the preparation of indoles having high compatibility with not only electron-donating and electron-withdrawing groups but also N- and O-protecting functional groups.
PYRIDINE BASED IONIC FLUORIDE FOR CATALYZING INDOLE AND TETRAZOLE FORMATION
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Paragraph 0031; 0115; 0116; 0121, (2020/01/02)
A pyridine based ionic liquid with a fluoride counter anion which catalyzes Fischer indole reaction and click chemistry. Methods of preparing the ionic liquid, and methods of utilizing the ionic liquid as a catalyst to synthesize indoles/indolenines and tetrazoles are also provided.
