- A convenient metal-free reagent for the generation and capture of trifluoromethanethiol
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O-Octadecyl-S-trifluorothiolcarbonate is a cheap and storable crystalline source of trifluoromethanethiol that can be prepared in two steps on a multigram scale from trifluoroacetic anhydride and sodium O-octadecyl-dithiocarbonate (xanthate). It reacts directly with gramines or with α-bromoketones and -esters in the presence of KF and pyrrolidine to give the corresponding trifluoromethyl sulfides in generally high yield.
- Li, Shi-Guang,Zard, Samir Z.
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- Visible-light-induced cascade dearomatization cyclization between alkynes and indole-derived bromides: A facile strategy to synthesize spiroindolenines
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A visible-light-initiated intermolecular dearomatization cyclization cascade reaction between alkynes and indole-derived bromides has been explored. This transformation exhibits a wide substrate scope and significant functional group tolerance, providing an efficient way to access a variety of spiroindolenines under mild conditions. This journal is
- Gao, Xiaoshuang,Yuan, Yao,Xie, Xiaomin,Zhang, Zhaoguo
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- 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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supporting information
p. 9016 - 9025
(2021/06/30)
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- Palladium-catalysed imidoylative spirocyclization of 3-(2-isocyanoethyl)indoles
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A palladium-catalysed construction of spiroindolines through dearomative spirocyclization of 3-(2-isocyanoethyl)indoles has been developed. 2′-Aryl-, vinyl-, and alkyl-substituted spiroindolines could be accessed under mild conditions with excellent functional group tolerance. C1-tethered oxindole- and indole-spiroindoline bisheterocycles were generated in high yieldsviaalkene/allene insertion and an imidoylative spirocyclization cascade. Additionally, a tandem dearomatization of two different indoles was realized withN-(2-bromobenzoyl)indoles as the electrophilic coupling partner of 3-(2-isocyanoethyl)indoles, affording polyindoline-spiroindoline bisheterocyclic scaffolds conveniently. Under the catalysis of Pd(OAc)2and a spinol-derived phosphoramidite ligand, chiral spiroindolines were successfully accessed with up to 95% yield and 85% ee.
- Tang, Shi,Ding, Shumin,Li, Dan,Li, Lianjie,Zhao, Haixia,Chai, Minxue,Wang, Jian
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supporting information
p. 10576 - 10579
(2021/10/19)
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- I2-induced cascade cyclization and dearomatization of indoles for the highly efficient synthesis of iodinated and vinylic spiroindolenines
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The spiroindolenine framework is a privileged heterocyclic motif and is widely present in numerous indole alkaloids. Herein, we develop a metal-free and environmentally friendly approach for the intramolecular cascade cyclization and dearomatization of indole derivatives to selectively afford iodinated and vinylic spiroindolenines by a substrate-controlled strategy. Simple operation, mild conditions, and high yield make this strategy a green and attractive pathway to construct functionalizable spiroindolenine scaffolds, which could be converted into diverse useful spiroindolenine derivatives.
- Li, Yazhou,Liang, Xuewu,Liu, Hong,Liu, Qi,Liu, Xuyi,Wei, Xiaohui,Zhou, Yu
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supporting information
p. 9165 - 9171
(2021/11/23)
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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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- 5-(Cyano)dibenzothiophenium Triflate: A Sulfur-Based Reagent for Electrophilic Cyanation and Cyanocyclizations
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The synthesis of 5-(cyano)dibenzothiophenium triflate 9, prepared by activation of dibenzo[b,d]thiophene-5-oxide with Tf2O and subsequent reaction with TMSCN is reported, and its reactivity as electrophilic cyanation reagent evaluated. The scalable preparation, easy handling and broad substrate scope of the electrophilic cyanation promoted by 9, which includes amines, thiols, silyl enol ethers, alkenes, electron rich (hetero)arenes and polyaromatic hydrocarbons, illustrate the synthetic potential of this reagent. Importantly, Lewis acid activation of the reagent is not required for the transfer process. We additionally report herein biomimetic cyanocyclization cascade reactions, which are not promoted by typical electrophilic cyanation reagents, demonstrating the superior ability of 9 to trigger challenging transformations.
- Li, Xiangdong,Golz, Christopher,Alcarazo, Manuel
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supporting information
p. 9496 - 9500
(2019/06/27)
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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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- GENERATION AND CYCLOADDITION REACTIONS OF INDOLE-2,3-QUINODIMETHANES
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N-methyl and N-tert-butoxycarbonylindole-2,3-quinodimethanes (2 and 3) have been generated and observed to undergo intermolecular cycloaddition reactions with dienophiles.
- Marinelli, Edmund R.
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p. 2745 - 2748
(2007/10/02)
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- Displacement of the Indolyl Sulfide Linkage in the Synthesis of 3-Substituted Indoles (1)
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The indolyl sulfide compounds (5,6,7,8) gave 3-3'-diindole methane derivatives by a double decomposition-displacement reaction.These same compounds when reacted with alkoxides yielded 3-alkoxymethylindole derivatives (9-14).
- Bennett, Richard Jr.,Maggiolo Allison,Shah Tushar
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p. 391 - 394
(2007/10/02)
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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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