19006-15-6Relevant academic research and scientific papers
One-pot, three-component Fischer indolisation-N-alkylation for rapid synthesis of 1,2,3-trisubstituted indoles
Hughes-Whiffing, Christopher A.,Perry, Alexis
supporting information, p. 627 - 634 (2021/02/06)
A one-pot, three-component protocol for the synthesis of 1,2,3-trisubstituted indoles has been developed, based upon a Fischer indolisation-indoleN-alkylation sequence. This procedure is very rapid (total reaction time under 30 minutes), operationally straightforward, generally high yielding and draws upon readily available building blocks (aryl hydrazines, ketones, alkyl halides) to generate densely substituted indole products. We have demonstrated the utility of this process in the synthesis of 23 indoles, benzoindoles and tetrahydrocarbazoles bearing varied and useful functionality.
Catalytic Carbon-Carbon Bond Activation of Saturated and Unsaturated Carbonyl Compounds via Chelate-Assisted Coupling Reaction with Indoles
Pannilawithana, Nuwan,Yi, Chae S.
, p. 5852 - 5861 (2020/07/21)
The chelate assistance strategy was devised to promote a highly regioselective catalytic C-C bond activation reaction of saturated and unsaturated carbonyl compounds. The cationic Ru-H complex 1 was found to be an effective catalyst for mediating the coupling reaction of 1,2-disubstituted indoles with α,β-unsaturated aldehydes and ketones, in which the regioselective Cα-Cβ activation of the carbonyl substrates has been achieved in forming the 3-alkylindole products. The analogous coupling reaction of indoles with saturated aldehydes and ketones directly led to the Cα-Cβ cleavage of the carbonyl substrates in forming the 3-alkylindole products. The coupling reaction of 1,2-dimethylinole with (E)-3-nonen-2-one and 2-propanol-d8 showed 20-22percent of deuterium incorporation to both α-and β-CH2 of the 3-alkylindole product. The coupling reaction of 1,2-dimethylinole with (E)-3-nonen-2-one exhibited the most significant carbon kinetic isotope effect on the α-carbon of the product (Cα = 1.046). The Hammett plot constructed from the reaction of 1,2-dimethylinole with a series of para-substituted enones p-X-C6H4CH=CHCOCH3 (X = OMe, Me, H, Cl, CF3) showed a modest promotional effect by an electron-donating group (ρ =-0.2 ± 0.1). Several catalytically relevant Ru-H species were detected by NMR from a stoichiometric reaction mixture of the Ru-H complex 1 with 1,2-dimethylindole and (E)-3-nonen-2-one in CD2Cl2. These results support a mechanism of the catalytic coupling reaction via conjugate addition of indoles to enones followed by the C-C bond activation and hydrogenolysis steps.
B(C6F5)3-Catalyzed Direct C3 Alkylation of Indoles and Oxindoles
Basak, Shyam,Alvarez-Montoya, Ana,Winfrey, Laura,Melen, Rebecca L.,Morrill, Louis C.,Pulis, Alexander P.
, p. 4835 - 4840 (2020/04/22)
The direct C3 alkylation of indoles and oxindoles is a challenging transformation, and only a few direct methods exist. Utilizing the underexplored ability of triaryl boranes to mediate the heterolytic cleavage of α-nitrogen C-H bonds in amines, we have developed a catalytic approach for the direct C3 alkylation of a wide range of indoles and oxindoles using amine-based alkylating agents. We also employed this borane-catalyzed strategy in an alkylation-ring opening cascade.
Co(III)-Catalyzed, Internal and Terminal Alkyne-Compatible Synthesis of Indoles
Zhou, Shuguang,Wang, Jinhu,Wang, Lili,Chen, Kehao,Song, Chao,Zhu, Jin
supporting information, p. 3806 - 3809 (2016/08/16)
A Co(III)-catalyzed, internal and terminal alkyne-compatible indole synthesis protocol is reported herein. The N-amino (hydrazine) group imparts distinct, diverse reactivity patterns for directed C-H functionalization/cyclization reactions. Notable synthetic features include regioselectivity for a meta-substituted arylhydrazine, regioselectivity for a chain-branched terminal alkyne, formal incorporation of an acetylenic unit through C2-desilylation on a C2-silylated indole derivative, formal inversion of regioselectivity through consecutive C3-derivatization and C2-desilylation processes, and formal bond migration for a linear-chain terminal alkyne.
Transition-Metal-Catalyzed Regioselective Alkylation of Indoles with Alcohols
Putra, Anggi Eka,Takigawa, Kei,Tanaka, Hatsuki,Ito, Yoshihiko,Oe, Yohei,Ohta, Tetsuo
, p. 6344 - 6354 (2013/10/21)
The regioselective alkylation of indoles with alcohols as alkylating reagents was developed by using Pd/C or RuCl2(PPh3) 3/DPEphos {DPEphos = bis[(2-diphenylphosphanyl)phenyl] ether}as catalysts. The reaction of indole with benzyl alcohol in the presence of Pd/C and K2CO3 at 80 °C for 24 h without any solvent under in air yielded 90 % of 3-benzylindole. The corresponding 3-benzylindole was obtained in 99 % yield when the reaction was catalyzed by RuCl 2(PPh3)3/DPEphos in the presence of K 3PO4 at 165 °C for 24 h under argon. Several types of alcohols were treated with indoles under these conditions to give the corresponding 3-alkylated indoles in high yields (up to 99 %). This reaction may involve the catalyst-mediated transformation of alcohols to aldehydes, nucleophilic addition of indole to the resulting aldehydes accompanied by dehydration, and then hydrogenation. Copyright
From alcohols to indoles: A tandem Ru catalyzed hydrogen-transfer Fischer indole synthesis
Porcheddu, Andrea,Mura, Manuel G.,De Luca, Lidia,Pizzetti, Marianna,Taddei, Maurizio
supporting information, p. 6112 - 6115 (2013/02/25)
In a new version of the Fischer indole synthesis, primary and secondary alcohols have been catalytically oxidized in the presence of phenylhydrazines and protic or Lewis acids to give the corresponding indoles. The overall reaction can be accomplished in one step, and the use of alcohols instead of aldehyes or ketones as starting materials has several advantages in terms of a large selection of reagents, easy handling, and safety of the process.
Rapid and general protocol towards catalyst-free friedel-crafts C-alkylation of indoles in water assisted by microwave irradiation
De Rosa, Margherita,Soriente, Annunziata
experimental part, p. 1029 - 1032 (2010/04/25)
An efficient and simplified protocol for uncatalyzed FriedelCrafts alkylation of indoles using microwave irradiation in water is described. A series of functionalized indole derivatives has been synthesized in very short times with moderate to good yields. The combination of microwave irradiation and superheated water offers significant advantages over conventional methods, such as higher selectivities, simplicity, shorter reaction times, and no need for a catalyst.
SQUARYLIUM COMPOUND, OPTICAL RECORDING MEDIUM USING THE SAME, RECORDING/REPRODUCTION METHOD AND OPTICAL RECORDING APPARATUS
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Page/Page column 70-71, (2008/06/13)
To provide a squarylium compound forming a metal complex, expressed by the general formula (I): where R1 and R2 are the same or different and each of R1 and R2 represents a substituted or unsubstituted alkyl, ar
A Mild and Selective C-3 Reductive Alkylation of Indoles
Appleton, Julie E.,Dack, Kevin N.,Green, Andrew D.,Steele, John
, p. 1529 - 1532 (2007/10/02)
In the presence of triethylsilane and trifluoroacetic acid, the reaction between indoles and aldehydes in dichloromethane at 0 deg C, results in good yields of C-3 reductively alkylated products.The transformation is most effective for the preparation of 3-(arylmethyl)indoles 6 from aromatic aldehydes.
Reactions of Dimethyl Acetylenedicarboxylate with Indoles having Bulky 3-Substituents, and Further Reactions of Pyrroloindoles
Letcher, Roy M.,Choi, Michael C. K.,Wai, John S. M.
, p. 2629 - 2659 (2007/10/02)
The addition of dimethyl acetylenedicarboxylate to nine pyrroloindoles, and to nine N-methylindoles with bulky 3-substituents, has yielded twenty three new adducts.Their structures, elucidated mainly from spectroscopy which includes extensive diagnostic use of 13C-1H n.m.r. coupling constants, show several novel features, but all adducts are related to known adduct types.The results show that for relatively unstrained pyrroloindoles, the formation of an amino-ketone intermediate is still significant, but not dominant, that bulky 3-alkyl substituents of indoles can be eliminated to give 2-hydroxycarbazoles, and also that 3-phenyl groups appear to inhibit any reaction.
