- An efficient method for the N-debenzylation of aromatic heterocycles
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The N-debenzylation of aromatic heterocycles such as substituted pyrroles and indoles, having functional groups like ester, amide, halo, and nitrile, by using sodium in liquid ammonia in the presence of t-BuOH at -78°C cleanly affords N-debenzylated aromatic heterocycles in good yields.
- Rao, T. Srinivasa,Pandey, Pramod S.
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- Gold(I)-Catalysed Hydroarylation of 1,3-Disubstituted Allenes with Efficient Axial-to-Point Chirality Transfer
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Hydroarylation of enantioenriched 1,3-disubstituted allenes has the potential to proceed with axial-to-point chirality transfer to yield enantioenriched allylated (hetero)aryl compounds. However, the gold-catalysed intermolecular reaction was previously reported to occur with no chirality transfer owing to competing allene racemisation. Herein, we describe the development of the first intermolecular hydroarylations of allenes to proceed with efficient chirality transfer and summarise some of the key criteria for achieving high regio- and stereoselectivity.
- Sutherland, Daniel R.,Kinsman, Luke,Angiolini, Stuart M.,Rosair, Georgina M.,Lee, Ai-Lan
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- Regioselective 2-alkylation of indoles with α-bromo esters catalyzed by Pd/P,P=O system
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A palladium-catalyzed 2-alkylation of indoles with α-bromo esters is developed by employing a P,P=O ligand. The method features excellent regioselectivities, mild reaction conditions, and good functional group compatibility. The employment of the P,P=O ligand as well as 4? molecular sieves were crucial for the success of the transformation. Mechanistic studies indicate the reaction proceed through a radical pathway.
- Tian, Wei,Li, Bowen,Tian, Duanshuai,Tang, Wenjun
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supporting information
p. 197 - 200
(2021/08/13)
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- Advancing Base-Metal Catalysis: Development of a Screening Method for Nickel-Catalyzed Suzuki-Miyaura Reactions of Pharmaceutically Relevant Heterocycles
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Interest in replacing palladium catalysts with base metals resulted in the development of a 24-reaction screening platform for identifying nickel-catalyzed Suzuki-Miyaura reaction conditions. This method was designed to be directly applicable to process s
- Goldfogel, Matthew J.,Guo, Xuelei,Gurak, John A.,Joannou, Matthew V.,Meléndez Matos, Jeishla L.,Moffat, William B.,Simmons, Eric M.,Wisniewski, Steven R.
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supporting information
(2021/08/18)
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- Synthesis of bisindolylmethane, bispyrrolylmethane, and indolylpyrrolylmethane derivatives via reductive heteroarylation
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An efficient and general reductive heteroarylation approach toward the synthesis of bisindolylmethane, bispyrrolylmethane, and indolylpyrrolylmethane derivatives has been developed. Thus, treatment of acylpyrrole or acylindole derivatives with indoles or pyrroles in the presence of a combination of sodium borohydride and acetic acid resulted in the formation of the title compounds in moderate to excellent isolated yields.
- Zhou, Hang,Huang, Zhuo,Huang, He,Song, Chuanjun,Chang, Junbiao
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- Nickel-catalyzed C3-alkylation of indoles with alcohols: Via a borrowing hydrogen strategy
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An efficient method for the Ni-catalyzed C3-alkylation of indoles using readily available alcohols as the alkylating reagents has been developed. The alkylation was addressed with an air and moisture-stable binuclear nickel complex ligated by tetrahydroquinolin-8-one as the effective pre-catalyst. The newly developed transformation could accommodate a broad substrate scope including primary/secondary benzylic and aliphatic alcohols and substituted indoles. Mechanistic studies suggested that the reaction proceeds through a borrowing hydrogen pathway.
- Hu, Miao,Jiang, Yong,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan,Jin, Liqun
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p. 10057 - 10062
(2021/06/15)
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- Ni-catalyzed reductive decyanation of nitriles with ethanol as the reductant
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A nickel-catalyzed reductive decyanation of aromatic nitriles has been developed, in which the readily available and abundant ethanol was applied as the hydride donor. Various functional groups on the aromatic rings, such as alkoxyl, amino, imino and amide, were compatible in this catalytic protocol. Heteroaryl, benzylic and alkenyl nitriles were also tolerated. Mechanistic investigation indicated that ethanol provided hydride efficientlyviaβ-hydride elimination in this reductive decyanation.
- Wu, Ke,Ling, Yichen,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Jin, Liqun,Hu, Xinquan
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supporting information
p. 2273 - 2276
(2021/03/09)
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- Replacing halogenated solvents by a butyl acetate solution of bisphenol S in the transformations of indoles
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A butyl acetate solution of bisphenol S (BPS) was proved to be able to replace hazardous halogenated solvents in the transformation of indoles. Measurement with Kamlet-Taft solvatochromic parameters disclosed that the polarity of the BPS-containing butyl acetate was enhanced greatly. The protocol not only conferred a convenient way to minimize the use of halogenated solvents in the synthesis of indole derivatives, but also enabled successful recycling of both the butyl acetate solvent and BPS additive, strengthening the greenness of the reaction systems.
- Bai, Rongxian,Ferlin, Francesco,Gao, Feng,Gu, Yanlong,Li, Minghao,Vaccaro, Luigi
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supporting information
p. 3588 - 3594
(2021/06/06)
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- Synthesis of 3-halogenated 2,3′-biindoles by a copper-mediated 2,3-difunctionalization of indoles
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A copper-mediated 2,3-difunctionalization of indoles to afford 3-halogenated 2,3′-biindoles is described herein. The protocol uses readily available feedstocks and a naturally abundant copper catalyst system, which allows the regioselective formation of C-C and C-X (X = Cl & Br) bonds in one single operation. Here the copper metal salt serves not only as a catalyst but also as a reactant to provide the source of halogen. This operationally simple procedure avoids the utilization of environmentally unfriendly reagents and displays good functional group compatibility. Noteworthily, the introduction of halogen into molecules would offer great potential for further chemical transformations. This journal is
- Gu, Xiaoting,Liang, Taoyuan,Wei, Wanxing,Zhang, Xiaoxiang,Zhang, Yingying,Zhang, Zhuan
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supporting information
p. 10403 - 10407
(2021/12/17)
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- Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
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Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
- Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
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supporting information
p. 7738 - 7744
(2021/05/07)
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- METHOD FOR PRODUCING AROMATIC COMPOUND USING HETEROGENEOUS NOBLE METAL CATALYST
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PROBLEM TO BE SOLVED: To provide a technique for synthesizing aromatic compound such as indole by dehydrogenation reaction that is low in manufacturing cost, and a green technique that is low in environmental impact. SOLUTION: Provided is a method for pro
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Paragraph 0038-0041; 0053-0056
(2021/09/15)
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- Manganese(III) Acetate Catalyzed Aerobic Dehydrogenation of Tertiary Indolines, Tetrahydroquinolines and an N-Unsubstituted Indoline
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A Mn(OAc)3 ? 2H2O-catalyzed aerobic dehydrogenation of five and six-membered N-heterocycles for the synthesis of N-heteroarenes is reported. Of note, this protocol can be applied to the dehydrogenation of tertiary indolines with various electron-deficient N-substituents. Preliminary mechanistic investigations support that a single-electron transfer pathway might be involved. (Figure presented.).
- Niu, Xiaokang,Yang, Lei
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supporting information
p. 4209 - 4215
(2021/08/06)
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- Copper-Catalyzed Synthesis of Indolyl Benzo[b]carbazoles and Their Photoluminescence Property
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A copper-catalyzed cascade cyclization of dihydroisobenzofurans with indoles for the rapid construction of indoly benzo[b]carbazoles has been reported, providing the desired products in moderate to good yields under mild conditions along with a broad substrate scope and good functional group tolerance. The photoluminescence property of these indoly benzo[b]carbazoles has also been investigated.
- Hao, Tonggang,Huang, Long,Wei, Yin,Shi, Min
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supporting information
p. 5133 - 5137
(2021/07/19)
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- A Catalytic One-Pot Synthesis of Indolyl Cyclobutanones
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A general strategy for the synthesis of indolyl cyclobutanones via a tandem Bronsted acid catalyzed 2-hydroxycyclobutanone activation-indole nucleophilic addition has been exploited. The procedure leads to a wide range of 2- and 3-functionalized indole derivatives in good to high yields with broad substrate scope.
- Porcu, Stefania,Rodriguez, Carla Aira,Frongia, Angelo,Secci, Francesco
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supporting information
p. 925 - 932
(2020/12/14)
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- Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation
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1,5-Disubstituted indole-2-carboxaldehyde derivatives 1a–h and glycine alkyl esters 2a–c are shown to undergo a novel cascade imination-heterocylization in the presence of the organic base DIPEA to provide 1-indolyl-3,5,8-substituted γ-carbolines 3aa–ea in good yields. The γ-carbolines are fluorescent and exhibit anticancer activities against cervical, lung, breast, skin, and kidney cancer cells.
- Chelvam, Venkatesh,Dudhe, Premansh,Krishnan, Mena Asha,Pathak, Biswarup,Roy, Diptendu,Venkatasubbaiah, Krishnan,Yadav, Kratika
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supporting information
p. 1453 - 1463
(2021/07/02)
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- N-2-pyrimidyl-3-fluoroindole compound and preparation method and application thereof
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The preparation method of the N-2-pyrimidinyl-3-fluoroindole compound shown in the formula (I) comprises the following steps: by taking an acetonitrile solvent as a reaction medium, adding the N-2-pyrimidinyl indole compound shown in the formula (III), se
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Paragraph 0058; 0061
(2021/03/31)
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- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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supporting information
p. 2095 - 2103
(2021/03/26)
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- Assembly of polycyclic N-heterocycles: Via copper-catalyzed cycloamination of indolylquinones and aromatic amines
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The copper-catalyzed cycloamination of indolylquinones and various (hetero)aromatic amines under ligand-free conditions for the synthesis of polycyclic N-heterocycles has been developed. This method allows facile access to polycyclic N-heterocycles with the tolerance of chloride, bromide, amino, thio, etc. groups in moderate to high yields (60-89%).
- Dong, Yu,Mei, Ting,Ye, Ji-Xian,Chen, Xiang-Long,Jiang, Hui,Chang, Bo,Wang, Zhi-Fan,Shi, Zhi-Chuan,Li, Zhong-Hui,He, Bing
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supporting information
p. 4593 - 4598
(2021/05/31)
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- Discovery of New 4-Indolyl Quinazoline Derivatives as Highly Potent and Orally Bioavailable P-Glycoprotein Inhibitors
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The major drawbacks of P-glycoprotein (P-gp) inhibitors at the clinical stage make the development of new P-gp inhibitors challenging and desirable. In this study, we reported our structure-activity relationship studies of 4-indolyl quinazoline, which led to the discovery of a highly effective and orally active P-gp inhibitor, YS-370. YS-370 effectively reversed multidrug resistance (MDR) to paclitaxel and colchicine in SW620/AD300 and HEK293T-ABCB1 cells. YS-370 bound directly to P-gp, did not alter expression or subcellular localization of P-gp in SW620/AD300 cells, but increased the intracellular accumulation of paclitaxel. Furthermore, YS-370 stimulated the P-gp ATPase activity and had moderate inhibition against CYP3A4. Significantly, oral administration of YS-370 in combination with paclitaxel achieved much stronger antitumor activity in a xenograft model bearing SW620/Ad300 cells than either drug alone. Taken together, our data demonstrate that YS-370 is a promising P-gp inhibitor capable of overcoming MDR and represents a unique scaffold for the development of new P-gp inhibitors.
- Chen, Zhe-Sheng,Dai, Qing-Qing,Li, Guo-Bo,Liu, Hong-Min,Liu, Hui,Wang, Bo,Wang, Shaomeng,Yu, Bin,Yuan, Shuo,Zhang, Jing-Ya,Zhang, Xiao-Nan,Zuo, Jia-Hui
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p. 14895 - 14911
(2021/10/12)
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- Palladium-Catalyzed Three-Component Regioselective Dehydrogenative Coupling of Indoles, 2-Methylbut-2-ene, and Carboxylic Acids
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Five-carbon (C5) structural units are the fundamental building blocks of many natural products. An unprecedented palladium-catalyzed three-component dehydrogenative cascade coupling of indoles, 2-methylbut-2-ene, and carboxylic acids has been developed. The approach enables the straightforward introduction of a C3′-bonded five-carbon structural unit with a tertiary alcohol quaternary carbon center into indoles. The protocol employs 2-methylbut-2-ene as the C5 source and is featured by a broad substrate scope, atom and step economies, and high chemo- and regioselectivies.
- Guo, Rui-Li,Jia, Qiong,Wang, Meng-Yue,Wang, Yong-Qiang,Yang, Jin-Hui,Zhang, Xing-Long,Zhao, Bao-Yin
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supporting information
p. 9574 - 9579
(2021/12/14)
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- Three-component reactions of 3-arylidene-3h-indolium salts, isocyanides and amines
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A multicomponent reaction of isocyanides with aryl(indol-3-yl)methylium salts and amines has been found. A series of aryl(indol-3-yl)acetimidamides was obtained in up to 96% yields. In the case of ethyl isocyanoacetate, the reaction is followed by cyclization to form 3,5-dihydro-4H-imidazol-4-one derivatives.
- Nguyen, Hung M.,Golantsov, Nikita E.,Golubenkova, Alexandra S.,Rybakov, Victor B.,Voskressensky, Leonid G.
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- Anti-leukemic properties of aplysinopsin derivative ee-84 alone and combined to bh3 mimetic a-1210477
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Aplysinopsins are a class of marine indole alkaloids that exhibit a wide range of biological activities. Although both the indole and N-benzyl moieties of aplysinopsins are known to possess antiproliferative activity against cancer cells, their mechanism of action remains unclear. Through in vitro and in vivo proliferation and viability screening of newly synthesized aplysinopsin analogs on myelogenous leukemia cell lines and zebrafish toxicity tests, as well as analysis of differential toxicity in noncancerous RPMI 1788 cells and PBMCs, we identified EE-84 as a promising novel drug candidate against chronic myeloid leukemia. This indole derivative demonstrated drug-likeness in agreement with Lipinski’s rule of five. Furthermore, EE-84 induced a senescent-like phenotype in K562 cells in line with its cytostatic effect. EE-84-treated K562 cells underwent morphological changes in line with mitochondrial dysfunction concomitant with autophagy and ER stress induction. Finally, we demonstrated the synergistic cytotoxic effect of EE-84 with a BH3 mimetic, the Mcl-1 inhibitor A-1210477, against imatinib-sensitive and resistant K562 cells, highlighting the inhibition of antiapoptotic Bcl-2 proteins as a promising novel senolytic approach against chronic myeloid leukemia.
- Song, Sungmi,Kim, Sua,El-Sawy, Eslam R.,Cerella, Claudia,Orlikova-Boyer, Barbora,Kirsch, Gilbert,Christov, Christo,Dicato, Mario,Diederich, Marc
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- γ-Carboline synthesis enabled by Rh(iii)-catalysed regioselective C-H annulation
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A redox-neutral Rh(iii)-catalyzed C-H annulation of indolyl oximes was developed. Relying on the use of various alkynyl silanes as the terminal alkyne surrogates, the reaction exhibited a reverse regioselectivity, thus giving an exclusive and easy way for the synthesis of a wide range of substituent free γ-carbolines at C3 position with high efficiency. Deuterium-labelling experiments and kinetic analysis have preliminarily shed light on the working mode of this catalytic system. This journal is
- Jiang, Bo,Jia, Jingwen,Sun, Yufei,Wang, Yichun,Zeng, Jing,Bu, Xiubin,Shi, Liangliang,Sun, Xiaoying,Yang, Xiaobo
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supporting information
p. 13389 - 13392
(2020/11/10)
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- Manganese-Catalyzed Regioselective Dehydrogenative C-versus N-Alkylation Enabled by a Solvent Switch: Experiment and Computation
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The first base metal-catalyzed regioselective dehydrogenative alkylation of indolines using readily available alcohols as the alkylating reagent is reported. A single air-and moisture-stable manganese catalyst provides access to either C3-or N-alkylated indoles depending on the solvent used. Mechanistic studies indicate that the reaction takes place through a combined acceptorless dehydrogenation and hydrogen autotransfer strategy.
- Borghs, Jannik C.,Zubar, Viktoriia,Zubar, Viktoriia,Azofra, Luis Miguel,Sklyaruk, Jan,Rueping, Magnus,Rueping, Magnus
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supporting information
p. 4222 - 4227
(2020/06/04)
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- Straightforward access to novel indolo[2,3-: B] indoles via aerobic copper-catalyzed [3+2] annulation of diarylamines and indoles
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Herein, we report an unprecedented aerobic copper-catalyzed [3+2] annulation reaction of diarylamines with indoles, which allows direct access to novel 2-diarylaminoindolo[2,3-b]indoles, a class of potential photoelectric device molecules. The developed transformation proceeds with broad substrate scope, good functional group tolerance, high chemo-selectivity, and no need for pre-preparation of specific agents, which offers a practical route for diverse and atom-economic synthesis of the desired products that are difficult to prepare with the conventional approaches.
- Gong, Lingzhen,Jiang, Huanfeng,Liang, Taoyuan,Zhang, Min,Zhao, He
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supporting information
p. 2807 - 2810
(2020/03/13)
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- Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor
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Novel approaches for N- and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KOtBu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KOtBu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.
- Heredia, Micaela D.,Guerra, Walter D.,Barolo, Silvia M.,Fornasier, Santiago J.,Rossi, Roberto A.,Budén, Mariá E.
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p. 13481 - 13494
(2020/12/15)
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- A rhodium(ii) catalysed domino synthesis of azepino fused diindoles from isatin tethered: N -sulfonyl-1,2,3-triazoles and indoles
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An efficient and convenient protocol for the synthesis of a novel class of azepino fused diindoles from isatin tethered N-sulfonyl-1,2,3-triazoles and indoles has been disclosed. The reaction proceeds via denitrogenative aza-vinyl rhodium carbene formation to give a carbonyl ylide, which with indole results in 1,3-dipolar cycloaddition followed by sequential semipinacol rearrangement/ring expansion/oxidation to produce azepino fused diindoles. The reaction shows a broad substrate scope giving up to 81% yield. Furthermore, reversible catalytic hydrogenation and photophysical studies were carried out to demonstrate the application of these molecules.
- Kahar, Nilesh,Jadhav, Pankaj,Reddy, R. V. Ramana,Dawande, Sudam
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supporting information
p. 1207 - 1210
(2020/02/04)
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- Cobalt-Catalyzed Cycloamination: Synthesis and Photophysical Properties of Polycyclic N-Heterocycles
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The first earth-abundant cobalt-catalyzed cycloamination of indolylquinones and various (hetero)aromatic amine under ligand-free conditions for the synthesis of polycyclic N-heterocycles has been developed. The process allows facile access to polycyclic N-heterocycles with tolerance of chloride, bromide, amino, thio, etc. groups in moderate to high yields (up to 89percent). In addition, The photophysical properties of the synthesized products were evaluated. These products exhibit interesting fluorescence properties, which is promising for fluorescent probes.
- Dong, Yu,He, Shuai,Shi, Zhi-Chuan,Wang, Ji-Yu,Yang, Jian,Zhan, Xiao-Yu,Zhang, Hua,Zhang, Xiao-Mei
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supporting information
(2020/07/15)
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- Tridentate Nickel(II)-Catalyzed Chemodivergent C-H Functionalization and Cyclopropanation: Regioselective and Diastereoselective Access to Substituted Aromatic Heterocycles
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A Schiff-base nickel(II)-phosphene-catalyzed chemodivergent C-H functionalization and cyclopropanation of aromatic heterocycles is reported in moderate to excellent yields and very good regioselectivity and diastereoselectivity. The weak, noncovalent interaction between the phosphene ligand and Ni center facilitates the ligand dissociation, generating the electronically and coordinatively unsaturated active catalyst. The proposed mechanisms for the reported reactions are in good accord with the experimental results and theoretical calculations, providing a suitable model of stereocontrol for the cyclopropanation reaction.
- Nag, Ekta,Gorantla, Sai Manoj N. V. T.,Arumugam, Selvakumar,Kulkarni, Aditya,Mondal, Kartik Chandra,Roy, Sudipta
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supporting information
p. 6313 - 6318
(2020/09/02)
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- One-pot heteroarene synthesis based on ruthenium-on-carbon-catalyzed oxidative aromatization using oxygen
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Various heteroarenes, such as indole, carbazole, dibenzofuran, dibenzothiophene, etc., were easily constructed by the Diels-Alder reaction of the corresponding vinyl-substituted pyrrole, indole, benzofuran or benzothiophene with the dienophiles and the su
- Sajiki, Hironao,Sawama, Yoshinari,Yamada, Yutaro,Yamamoto, Yuta
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supporting information
p. 1419 - 1423
(2020/12/28)
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- Ir-Catalyzed Reversible Acceptorless Dehydrogenation/Hydrogenation of N-Substituted and Unsubstituted Heterocycles Enabled by a Polymer-Cross-Linking Bisphosphine
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The polystyrene-cross-linking bisphosphine ligand PS-DPPBz was effective for the Ir-catalyzed reversible acceptorless dehydrogenation/hydrogenation of N-heterocycles. Notably, this protocol is applicable to the dehydrogenation of N-substituted indoline derivatives with various N-substituents with different electronic and steric natures. A reaction pathway involving oxidative addition of an N-adjacent C(sp3)-H bond to a bisphosphine-coordinated Ir(I) center is proposed for the dehydrogenation of N-substituted substrates.
- Zhang, Deliang,Iwai, Tomohiro,Sawamura, Masaya
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supporting information
p. 5240 - 5245
(2020/07/03)
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- Sulfoxide-Promoted Chlorination of Indoles and Electron-Rich Arenes with Chlorine as Nucleophile
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An efficient chlorination of indoles and electron-rich arenes with chlorine anion as nucleophile is described. With the use of ethyl phenyl sulfoxide as the promoter, the reaction went smoothly under metal-free and mild conditions. Various indoles and electron-rich arenes are converted into the corresponding chlorinated compounds in moderate to excellent yields. A plausible interrupted Pummerer reaction mechanism was proposed without the oxidation of chloride anion. In addition, the byproduct thioether could be easily converted to the starting material sulfoxide just by a simple oxidation reaction. (Figure presented.).
- Ji, Yuan-Zhao,Li, Hui-Jing,Wang, Yi-Ruo,Wu, Yan-Chao,Zhang, Zheng-Yan
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supporting information
(2020/02/05)
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- Iodine-Catalyzed Aerobic Diazenylation-Amination of Indole Derivatives
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A mild strategy for consecutive diazenylation and amination of indole moieties has been demonstrated. The functionalization occurs at C3 and C2 carbon atoms, respectively, at the indole scaffold in the presence of catalytic iodine and air at 40 °C in the 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) solvent. It is noteworthy that the aromatic amines are generated in situ by the reaction of aryl hydrazine with iodine. In general, bright red products are obtained in moderate to good yield. Control reactions are conducted to establish the reaction mechanism.
- Sar, Saibal,Tripathi, Ankita,Dubey, Kshatresh Dutta,Sen, Subhabrata
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p. 3748 - 3756
(2020/03/04)
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- Tethered Counterion-Directed Catalysis: Merging the Chiral Ion-Pairing and Bifunctional Ligand Strategies in Enantioselective Gold(I) Catalysis
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Tethering a metal complex to its phosphate counterion via a phosphine ligand enables a new strategy in asymmetric counteranion-directed catalysis (ACDC). A straightforward, scalable synthetic route gives access to the gold(I) complex of a phosphine displaying a chiral phosphoric acid function. The complex generates a catalytically active species with an unprecedented intramolecular relationship between the cationic Au(I) center and the phosphate counterion. The benefits of tethering the two functions of the catalyst are demonstrated here in a tandem cycloisomerization/nucleophilic addition reaction, by attaining high enantioselectivity levels (up to 97% ee) at an unusually low 0.2 mol % catalyst loading. Remarkably, the method is also compatible with a silver-free protocol.
- Frison, Gilles,Guinchard, Xavier,Marinetti, Angela,Retailleau, Pascal,Smal, Vitalii,Voituriez, Arnaud,Zhang, Zhenhao
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supporting information
p. 3797 - 3805
(2020/03/10)
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- Isothiourea-Catalyzed Enantioselective Synthesis of Tetrahydro-α-carbolinones
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An isothiourea-catalyzed enantioselective annulation protocol using indolin-2-imines with a series of α,β-unsaturated p-nitrophenyl esters for the synthesis of tetrahydro-α-carbolinones was developed. Using 5 mol % of the isothiourea HyperBTM as the Lewis base catalyst, this process allows the enantioselective preparation of a range of C(4)-substituted tetrahydro-α-carbolinones in good to excellent yield and with high enantioselectivity (20 examples, 32-99% yield and up to 99:1 er).
- Liu, Honglei,Slawin, Alexandra M. Z.,Smith, Andrew D.
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supporting information
p. 1301 - 1305
(2020/02/25)
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- Ru-Catalyzed Carbonylative Murai Reaction: Directed C3-Acylation of Biomass-Derived 2-Formyl Heteroaromatics
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The Murai reaction is a ruthenium-catalyzed transformation leading to alkylated arenes through the C?C bond formation between an alkene and an arene bearing a directing group. Discovered in the nineties, this useful C?H activation based coupling has been the object of intense study since its discovery. After having studied the Murai reaction on 2-formylfurans of biomass derivation, we describe here the carbonylative version applied to 2-formylfurans, 2-formylpyrrols and 2-formylthiophenes. This acylation reaction takes place regioselectively at C3 position of the heterocyclopentadienes thanks to the installation of removable imine directing groups. The transformation can be achieved by treating the two reaction partners with a catalytic amount of Ru3(CO)12, in toluene at 120–150 °C, after CO bubbling, at atmospheric pressure. DFT computations of the full catalytic cycle help in deciphering the mechanism of this transformation, and to rationalize the different behaviors depending on the nature of imine directing groups. (Figure presented.).
- Sala, Roberto,Roudesly, Fares,Veiros, Luis F.,Broggini, Gianluigi,Oble, Julie,Poli, Giovanni
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supporting information
p. 2486 - 2493
(2020/05/06)
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- Synthesis of Cyclopenta[b]indoles via a Formal [3+2] Cyclization of N-Sulfonyl-1,2,3-triazoles and Indoles
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Annulation of benzoxy-tethered N-sulfonyl-1,2,3-triazoles and indoles has been developed in this paper, providing an efficient and convenient access to valuable cyclopenta[b]indoles in moderate to good yields. α,β-Unsaturated imine, which generated in situ from denitrogenation and 1,2-OBz migration of triazole, provided three carbons for the formal [3+2] cyclization reaction for the first time. (Figure presented.).
- Duan, Shengguo,Zhang, Wan,Hu, Yuntong,Xu, Ze-Feng,Li, Chuan-Ying
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supporting information
p. 3570 - 3575
(2020/08/05)
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- Room-Temperature Palladium(II)-Catalyzed Direct 2-Arylation of Indoles with Tetraarylstannanes
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A palladium(II)-catalyzed direct 2-arylation of indoles by tetraarylstannanes with oxygen (balloon) as the oxidant at room temperature has been developed. Various tetraarylstannanes can be employed as aryl sources for 2-arylation of indoles in up to 89% yield, providing a practical and efficient catalytic protocol for accessing 2-arylindoles.
- Liu, Yuxia,Wang, Chao,Huang, Linjuan,Xue, Dong
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supporting information
p. 1613 - 1618
(2020/09/15)
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- The palladium-catalyzed direct C3-cyanation of indoles using acetonitrile as the cyanide source
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The ligand-free palladium-catalyzed C3-cyanation of indoles via direct C-H functionalization was achieved. This protocol, utilizing CH3CN as a green and readily available cyanide source, produced the desired products in moderate to good yields through transition-metal-catalyzed C-CN bond cleavage. This journal is
- Feng, Kejun,Li, Qiang,Li, Yuanhua,Liu, Bifu,Liu, Min,Zhou, Yongbo
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supporting information
p. 6108 - 6114
(2020/10/21)
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- Arylation of indoles using cyclohexanones dually-catalyzed by niobic acid and palladium-on-carbons
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3-Arylindoles were easily constructed from indoles and cyclohexanone derivatives using a combination of catalytic niobic acid-on-carbon (Nb2O5/C) and palladium-on-carbon (Pd/C) under heating conditions without any oxidants. The Lewis acidic Nb2O5/C promoted the nucleophilic addition of indoles to the cyclohexanones, and the subsequent dehydration and Pd/C-catalyzed dehydrogenation produced the 3-arylindoles. The additive 2,3-dimethyl-1,3-butadiene worked as a hydrogen acceptor to facilitate the dehydrogenation step.
- Ban, Kazuho,Sajiki, Hironao,Sawama, Yoshinari,Yamamoto, Yuta
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supporting information
p. 3898 - 3902
(2020/06/03)
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- Design, synthesis, biological evaluation and molecular modelling studies of conophylline inspired novel indolyl oxoacetamides as potent pancreatic lipase inhibitors
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A novel series of 21 indolyl oxoacetamide analogues was designed based on the natural product lead conophylline, and evaluated for their pancreatic lipase inhibitory activity using porcine pancreatic lipase (Type II). Analogues 12c and 12b exhibited comparatively greater potential (IC50 values of 2.95 and 3.26 μM) than conophylline (IC50-3.31 μM), while the standard drug, orlistat, exhibited a potent IC50 value of 0.99 μM. Further, analogues 12b and 12c exhibited reversible competitive inhibition similar to orlistat and conophylline, and possessed Ki values of 1.89 and 1.69 μM, respectively. Molecular docking of these analogues was in agreement with the in vitro results, wherein the MolDock scores exhibited significant correlation with their inhibitory activity. A 10 ns molecular dynamics simulation of 12c complexed with pancreatic lipase confirmed the role of extended alkyl interactions, along with π-π stacking and π-cation interactions, in stabilising the ligand in the active site (maximum observed RMSD ≈ 3.5 ?). ADMET prediction indicated the GI absorption of these analogues to be high; however, they did not possess carcinogenicity and hepatotoxicity in contrast to orlistat and conophylline.
- Palawat, Saksham,Paul, Atish T.,Sridhar, S. N. C.
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p. 12355 - 12369
(2020/08/03)
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- Catalyst-free assembly of giant tris(heteroaryl)methanes: Synthesis of novel pharmacophoric triads and model sterically crowded tris(heteroaryl/aryl)methyl cation salts
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A series of giant tris(heteroaryl)methanes are easily assembled by one-pot three-component synthesis by simple reflux in ethanol without catalyst or additives. Diversely substituted indoles (Ar1) react with quinoline aldehydes, quinolone aldehydes, chromone aldehydes, and fluorene aldehydes (Ar2CHO) and coumarins (Ar3) in 1:1:1 ratio to form the corresponding tris(heteroaryl)methanes (Ar1Ar2Ar3)CH along with (Ar1Ar1Ar2)CH triads. A series of new 2:1 triads were also synthesized by coupling substituted indoles with Ar2CHO. The coupling reactions could also be carried out in water (at circa 80 °C) but with chemoselectivity favoring (Ar1Ar1Ar2)CH(Ar1Ar2Ar3)CH. The molecular structure of a representative (Ar1Ar2Ar3)CH triad was confirmed by X-ray analysis. Model tris(heteroaryl/aryl)methylium salts were generated by reaction with DDQ/HPF6 and studied by NMR and by DFT and GIAO-DFT.
- Abonia, Rodrigo,Gutiérrez, Luisa F.,Insuasty, Braulio,Quiroga, Jairo,Laali, Kenneth K.,Zhao, Chunqing,Borosky, Gabriela L.,Horwitz, Samantha M.,Bunge, Scott D.
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p. 642 - 654
(2019/04/17)
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- Palladium-Catalyzed C-N Cross-Coupling of NH-Heteroarenes and Quaternary Ammonium Salts via C-N Bond Cleavage
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In this paper, we extend the substrate class of Buchwald-Hartwig amination to quaternary ammonium salts. In the presence of Pd(OAc)2 and t-BuXPhos, the coupling of aryl- or arylmethyltrimethylammonium triflates with NH-heteroarenes via C-N bond cleavage affords the desired N-aryl or N-arylmethyl heteroarenes in moderate to excellent yields.
- Chen, Hongyi,Yang, Hongqin,Li, Nutao,Xue, Xinghua,He, Ze,Zeng, Qingle
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p. 1679 - 1685
(2019/08/20)
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- Cobalt-Catalyzed Regioselective Direct C-4 Alkenylation of 3-Acetylindole with Michael Acceptors Using a Weakly Coordinating Functional Group
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Herein, we disclosed the first report on the selective C(4)-H functionalization of 3-acetylindole derivatives using first-row transition metal cobalt where an acetyl group is acting as a weakly coordinating directing group. Selective C(4)-H functionalization has been achieved using diverse Michael acceptors (acrylate and maleimide) simply by switching the additive from copper acetate to silver carbonate. Further the formation of a cobaltacycle intermediate was also detected through HRMS for mechanistic insight.
- Banjare, Shyam Kumar,Nanda, Tanmayee,Ravikumar
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supporting information
p. 8138 - 8143
(2019/10/14)
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- Tandem Rh(II) and Chiral Squaramide Relay Catalysis: Enantioselective Synthesis of Dihydro-β-carbolines via Insertion to C-H Bond and Aza-Michael Reaction
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An efficient tandem rhodium(II)/squaramide relay catalysis of readily accessible indole derivatives and N-sulfonyl-1,2,3-triazoles has been developed for the enantioselective synthesis of dihydro-β-carbolines in good yield and enantioselectivity. The developed reaction involves selective insertion of in situ generated azavinyl rhodium carbene onto the C3-H bond of indole derivatives and subsequent squaramide-catalyzed enantioselective intramolecular aza-Michael reaction. Furthermore, the potential of the strategy was demonstrated through the ready conversion to potent tetrahydro-β-carbolines and the tetracyclic alkaloid core structure.
- Rajasekar, Shanmugam,Anbarasan, Pazhamalai
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supporting information
p. 3067 - 3071
(2019/05/10)
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- Triphenylphosphine-free approach for one-pot N-alkylation of purine, pyrimidine, and azole derivatives with alcohols using P2O5/KI: A facile and selective route to access carboacyclic nucleosides
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A facile, selective, and mild synthetic approach for one-pot N-alkylation of nucleobases and other related N-heterocycles via alcohols, using a mixture of P2O5 and KI is described. The reaction of structurally diverse purines, pyrimidines, and/or azoles with primary alcohols with the use of P2O5/KI and basic mixture of Et3N/K2CO3 in refluxing DMF affords the corresponding N-alkyl derivatives (carboacyclic nucleosides) in good to reasonable yields. The influence of different parameters comprising solvent, base, temperature, and substrate/reagent ratios was assessed on the reaction progress. The secondary and tertiary alcohols were failed to react with nucleobases. The main advantageous of current protocol is formation of water soluble side products in which provides simple work-up and purification processes.
- Behrouz, Somayeh,Soltani Rad, Mohammad Navid,Ahmadi, Samira
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supporting information
(2019/08/12)
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- Efficient acceptorless photo-dehydrogenation of alcohols and: N -heterocycles with binuclear platinum(ii) diphosphite complexes
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Although photoredox catalysis employing Ru(ii) and Ir(iii) complexes as photocatalysts has emerged as a versatile tool for oxidative C-H functionalization under mild conditions, the need for additional reagents acting as electron donor/scavenger for completing the catalytic cycle undermines the practicability of this approach. Herein we demonstrate that photo-induced oxidative C-H functionalization can be catalysed with high product yields under oxygen-free and acceptorless conditions via inner-sphere atom abstraction by binuclear platinum(ii) diphosphite complexes. Both alcohols (51 examples), particularly the aliphatic ones, and saturated N-heterocycles (24 examples) can be efficiently dehydrogenated under light irradiation at room temperature. Regeneration of the photocatalyst by means of reductive elimination of dihydrogen from the in situ formed platinum(iii)-hydride species represents an alternative paradigm to the current approach in photoredox catalysis.
- Zhong, Jian-Ji,To, Wai-Pong,Liu, Yungen,Lu, Wei,Che, Chi-Ming
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p. 4883 - 4889
(2019/05/16)
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- Replacement of Stoichiometric DDQ with a Low Potential o-Quinone Catalyst Enabling Aerobic Dehydrogenation of Tertiary Indolines in Pharmaceutical Intermediates
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A transition-metal/quinone complex, [Ru(phd)3]2+ (phd = 1,10-phenanthroline-5,6-dione), is shown to be effective for aerobic dehydrogenation of 3° indolines to the corresponding indoles. The results show how low potential quinones may be tailored to provide a catalytic alternative to stoichiometric DDQ, due to their ability to mediate efficient substrate dehydrogenation while also being compatible with facile reoxidation by O2. The utility of the method is demonstrated in the synthesis of key intermediates to pharmaceutically important molecules.
- Li, Bao,Wendlandt, Alison E.,Stahl, Shannon S.
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supporting information
p. 1176 - 1181
(2019/02/14)
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- Mechanochemical Pd(II)-Catalyzed Direct and C-2-Selective Arylation of Indoles
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A mechanochemical method for the preparation of synthetically useful 2-arylindoles is developed using Pd(II) as the catalyst in the absence of phosphine ligands in a ball-mill. The developed protocol is highly C-2 selective and tolerant of structural variations with electron-rich and electron-deficient substituents both in indoles and iodoarenes. Arylation is possible in both unprotected indoles and N-protected indoles with the electron-donating group with the former substrate being relatively slower to react and little less yielding. Indoles with a deactivated five-membered ring could also take part in the reaction with ease. The scalability of the reaction was demonstrated by conducting the reaction in the gram scale. In general, the reactions were achieved in a shorter time than the conventional methods.
- Das, Dharmendra,Bhutia, Zigmee T.,Chatterjee, Amrita,Banerjee, Mainak
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p. 10764 - 10774
(2019/09/09)
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- Switchable regioselection of C-H thiolation of indoles using different TMS counterions
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A switchable regioselectivity in C-H thiolation reaction by simply swapping the counteranions of TMS is reported here for the first time. An exclusive C3-H thiolation of indoles with sodium arylsulfinates was achieved in the presence of TMSCl as a promoter. In contrast, with the use of TMSOTf instead of TMSCl under otherwise identical conditions, a regiospecific C2-H thiolation of indoles was realized with the same set of substrates.
- Ji, Yuan-Zhao,Li, Hui-Jing,Zhang, Jin-Yu,Wu, Yan-Chao
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supporting information
p. 11864 - 11867
(2019/10/11)
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- Catalytic Tandem Friedel-Crafts Alkylation/C4-C3 Ring-Contraction Reaction: An Efficient Route for the Synthesis of Indolyl Cyclopropanecarbaldehydes and Ketones
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A general strategy for the synthesis of indolyl cyclopropanecarbaldehydes and ketones via a Br?nsted acid-catalyzed indole nucleophilic addition/ring-contraction reaction sequence has been exploited. The procedure leads to a wide panel of cyclopropyl carbonyl compounds in generally high yields with a broad substrate scope.
- Turnu, Francesca,Luridiana, Alberto,Cocco, Andrea,Porcu, Stefania,Frongia, Angelo,Sarais, Giorgia,Secci, Francesco
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supporting information
p. 7329 - 7332
(2019/10/02)
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- Electrochemical Regioselective Bromination of Electron-Rich Aromatic Rings Using n Bu 4 NBr
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Electrochemical regioselective bromination of electron-rich aromatic rings using stoichiometric tetrabutylammonium bromide (n Bu 4 NBr) has been accomplished under mild conditions. This protocol provides an environmentally friendly and simple way for the construction of C-Br bond in moderate to high yields with wide functional group tolerance.
- Bai, Ya,Che, Xin,Liu, Nian,Ning, Shulin,Shi, Lingling,Wang, Shutao,Wang, Siyu,Xiang, Jinbao,Xie, Wenxia
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supporting information
p. 1313 - 1316
(2019/06/20)
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