- Catalyst-Controlled Regiodivergence in Rearrangements of Indole-Based Onium Ylides
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We have developed catalyst-controlled regiodivergent rearrangements of onium-ylides derived from indole substrates. Oxonium ylides formed in situ from substituted indoles selectively undergo [2,3]- and [1,2]-rearrangements in the presence of a rhodium and a copper catalyst, respectively. The combined experimental and density functional theory (DFT) computational studies indicate divergent mechanistic pathways involving a metal-free ylide in the rhodium catalyzed reaction favoring [2,3]-rearrangement, and a metal-coordinated ion-pair in the copper catalyzed [1,2]-rearrangement that recombines in the solvent-cage. The application of our methodology was demonstrated in the first total synthesis of the indole alkaloid (±)-sorazolon B, which enabled the stereochemical reassignment of the natural product. Further functional group transformations of the rearrangement products to generate valuable synthetic intermediates were also demonstrated.
- Nair, Vaishnavi N.,Kojasoy, Volga,Laconsay, Croix J.,Kong, Wang Yeuk,Tantillo, Dean J.,Tambar, Uttam K.
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- Rhodium-Catalyzed Stereoselective Cyclization of 3-Allenylindoles and N-Allenyltryptamines to Functionalized Vinylic Spiroindolenines
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Herein, we report a highly enantio- and diastereoselective rhodium-catalyzed cyclization of N-allenyltryptamines and 3-allenylindoles to 6-membered spirocyclic indolenines. This allylic addition methodology offers the advantage of using a comparably cheap commercially available ligand with low loadings of an affordable rhodium precursor. The products can be converted into functionalized spirooxindoles and spiroindolines, which are regarded as important building blocks for the synthesis of a lot of natural products with biological activities.
- Becker, Antonia,Breit, Bernhard,Grugel, Christian P.
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supporting information
p. 3788 - 3792
(2021/05/29)
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- Substitution of the Dimethylamino Group in Gramines and One-Pot Cyclization to Tetrahydro-β-carbolines Using a Triazine-Based Activating Agent
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A new method for the substitution of 3-[(dimethylamino)methyl]indoles (gramines) with malonate-based nucleophiles was developed using 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) as the activating agent for the dimethylamino group. The reaction was completed in 1.5-6 h at room temperature in the presence of a tert-amine base and lithium salt. CDMT afforded superior results to methyl iodide, a common activating agent for the dimethylamino group in Mannich bases, particularly in the reactions of 1-substituted gramines. The reactivity of the possible intermediates, bis(indol-3-ylmethyl)dimethylammonium salts, was examined to obtain mechanistic insights on the reaction. This substitution method with CDMT enabled the sequential transformation of gramines: substitution with (N-alkylidene)aminomalonates followed by the Pictet-Spengler reaction under acidic conditions afforded 1,2,3,4-tetrahydro-β-carboline derivatives in one pot.
- Fujita, Hikaru,Nishikawa, Riho,Sasamoto, Ozora,Kitamura, Masanori,Kunishima, Munetaka
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p. 8380 - 8391
(2019/07/08)
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- Rhodium-Catalyzed Enantioselective Cyclization of 3-Allenyl-indoles: Access to Functionalized Tetrahydrocarbazoles
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A highly selective rhodium-catalyzed cyclization of tethered 3-allenylindoles is reported. In a smooth reaction, 1-vinyltetrahydrocarbazoles are obtained in excellent yields and enantioselectivities. Aside from a great functional group tolerance, this method requires neither the Schlenk technique nor the use of anhydrous solvents. Preliminary mechanistic investigations proved that the reaction proceeds via an intermediary formed spiroindolenine which rapidly undergoes an acid-catalyzed stereospecific migration.
- Grugel, Christian P.,Breit, Bernhard
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supporting information
p. 5798 - 5802
(2019/06/08)
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- Rhodium-Catalyzed Diastereo- And Enantioselective Tandem Spirocyclization/Reduction of 3-Allenylindoles: Access to Functionalized Vinylic Spiroindolines
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A highly selective rhodium-catalyzed tandem spirocyclization/reduction of 3-allenylindoles is reported. By employing a Hantzsch ester as reductant, vinylic spiroindolines are obtained in excellent yields as well as diastereo- and enantioselectivity. In addition, the reaction's synthetic utility is highlighted by broad functional group compatibility and exemplified by a gram scale reaction with subsequent assorted transformations.
- Grugel, Christian P.,Breit, Bernhard
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supporting information
p. 9672 - 9676
(2019/12/24)
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- General Synthesis of Unsymmetrical 3,3′-(Aza)diindolylmethane Derivatives
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Diindolylmethane (DIM) and its derivatives have recently been in the focus of interest due to their significant biological activities, specifically in cancer prevention and therapy. Molecular targets of DIM have been identified, e.g., the immunostimulatory G protein-coupled receptor GPR84. However, most of the reported and investigated DIM derivatives are symmetrical because general methods for obtaining unsymmetrical DIMs have been lacking. To optimize the interaction of DIM derivatives with their protein targets, unsymmetrical substitution is required. In the present study we developed a new, mild and efficient access to unsymmetrically substituted 3,3′-DIMs by reaction of (3-indolylmethyl)trimethylammonium iodides with a wide range of substituted indole derivatives. 7-Azaindole also led to the 3,3′-connected DIM analogue, while 4- and 5-azaindoles reacted at the N1-nitrogen atom as confirmed by X-ray crystallography. The reactions were performed in water without the requirement of a catalyst or other additives. Wide substrate scope, operational simplicity, environmentally benign workup, and high yields are further advantages of the new method. The synthetic protocol proved to be suitable for upscaling to yield gram amounts for pharmacological studies. This procedure will allow the preparation of a broad range of novel, unsymmetrical DIM derivatives to exploit their potential as novel drugs.
- Pillaiyar, Thanigaimalai,Gorska, Ewelina,Schnakenburg, Gregor,Müller, Christa E.
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p. 9902 - 9913
(2018/08/01)
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- 5-METHOXYTRYPTOPHAN AND ITS DERIVATIVES AND USES THEREOF
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A 5-methoxytryptophan and its derivatives are disclosed, wherein the 5-methoxytryptophan and its derivatives are represented by the following formula (I): (I) wherein R1, R2, R3, R4, R5, and n are defined in the specification. In addition, the present invention also provides novel used of the 5-methoxytryptophan and its derivatives for treating inflammatory-related disease and cancers.
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Page/Page column 14; 15
(2016/08/10)
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- Mild microwave-assisted synthesis of dipyrromethanes and their analogues
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The Mannich reaction between pyrroles or indoles and Eschenmoser's salt (dimethylmethylideneammonium iodide) forms N,N-dimethylamino-methylated derivatives in good to excellent yields. The reaction is highly regioselective, and for pyrroles both 2-and 3-s
- Xiong, Ruisheng,Borbas, K. Eszter
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supporting information
p. 484 - 488
(2015/04/14)
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- A practical synthesis of indole-based heterocycles using an amidoaluminum-mediated strategy
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A large number of biologically active compounds consist of an indole scaffolding. Because of this, chemists are continually searching for more efficient means through which to successfully synthesize the required alkaloids. In our recent effort to synthes
- Todd, Robert,Hossain, M. Mahmun
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experimental part
p. 1846 - 1850
(2010/01/16)
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- 3-INDOLYL-TERTIARY BUTYLAMINOPROPANOLS
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1-Phenoxy-3-(3-indolyl)-tert.-butyl!amino-2-propanols and related 1-aryloxy compounds are antihypertensive agents having vasodilator and adrenergic β-receptor blocking action. Preferred compounds bear an ortho-substituent in the phenoxy group, and most preferably the cyano group.
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- Synthesis, DNA intercalation and antitumor activity of 9-hydroxy-11-demethylellipticine and some derivatives. Comparison with the corresponding ellipticines
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The authors report 3 synthetic routes leading to the 11-demethylellipticines. Their 9-methoxylated and 9-hydroxylated derivatives as well as their quaternary ammonium salts have been compared with the corresponding ellipticine derivatives concerning their DNA affinity, their in vitro cytotoxic action and their in vivo antitumor activity. The experimental results indicate that the 11-demethylellipticines show less DNA affinity but possess a much lower toxicity than the corresponding ellipticines, being at the same time also less active on L 1210 leukemia. It appears that the presence of a methyl group on the intercalating ring (at C-11) plays a major role in determining the biological activity. A similar observation has been made in the actinomycin series.
- Gouyette,Reynaud,Sadet,et al.
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p. 503 - 510
(2007/10/02)
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