- Evidence of a Nitrene Tunneling Reaction: Spontaneous Rearrangement of 2-Formyl Phenylnitrene to an Imino Ketene in Low-Temperature Matrixes
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Triplet 2-formyl phenylnitrene was generated by photolysis of 2-formyl phenylazide isolated in Ar, Kr, and Xe matrixes and characterized by IR, UV-vis, and EPR spectroscopies. Upon generation at 10 K, the triplet nitrene spontaneously rearranges in the dark to singlet 6-imino-2,4-cyclohexadien-1-ketene on the time scale of several hours. The intramolecular [1,4] H atom shift from the nitrene to the imino ketene occurs by tunneling, on the triplet manifold, followed by intersystem crossing. This case constitutes the first direct evidence of a tunneling reaction involving a nitrene.
- Nunes, Cláudio M.,Knezz, Stephanie N.,Reva, Igor,Fausto, Rui,McMahon, Robert J.
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- Synthesis of 3-Aryl-2-nitroindoles by Palladium-Catalyzed CH-Activation Reactions
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3-Aryl-2-nitroindoles were prepared via CH-activation reactions of N-methyl-2-nitroindole.
- Ivanov, Anton,Iaroshenko, Viktor O.,Villinger, Alexander,Langer, Peter
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- A simple synthesis of 2-{2-[(arylmethylidene)amino]-indazol-3-yl}malonate esters
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[Figure not available: see fulltext.] A method was developed for the synthesis of dimethyl {2-[(arylmethylidene)amino]-2H-indazol-3-yl}malonates on the basis of a Knoevenagel condensation between 2-azidobenzaldehyde and dimethyl malonate, followed by treatment of the obtained adduct with aromatic aldehydes in the presence of polymer-supported triphenylphosphine. It was shown that the interaction of the synthesized Schiff bases with Corey ylide provided a route for the synthesis of 2-(aziridin-1-yl)indazoles.
- Kuznetsova, Lyubov I.,Chagarovskiy, Alexey O.,Levina, Irina I.,Rybakov, Victor B.,Ivanova, Olga A.,Trushkov, Igor V.
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- Indolidenes and Indolidenium Intermediates in the Synthesis of Cyclopent[b]indoles: Mechanistic Studies on Intramolecular Cyclizations
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Tetracyclic products featuring predominantly a trans-hexahydroindane unit annelated onto the C(2)/C(3) positions of indole can be accessed by intramolecular cyclocondensation of tethered alkenyl sulfides with either indolidene or indolidenium cation intermediates. Studies with geometrically pure E- and Z-alkenyl sulfide isomers reveal a likely dichotomy of reaction paths that provide mixtures of both regioisomers and stereoisomers of the hexahydroindane adducts.
- Feldman, Ken S.,Gonzalez, Inanllely Y.,Glinkerman, Christopher M.
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- Novel substituted triazolo benzodiazepine scaffolds to explore chemical space
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Efficient and concise routes to sets of novel triazolo-1,4-benzodiazepine scaffolds that are suitably functionalized for diversification at three positions to explore three-dimensional space with different substituents are described. One approach to these scaffolds features a simplified multicomponent assembly process to give an intermediate azido alkyne that undergoes a facile Huisgen dipolar cycloaddition. The triazolo-1,4-benzodiazepines thus produced may be endowed with aryl halide, secondary amino, alcohol, aldehyde or carboxylic acid groups as functional handles for orthogonal derivatization reactions. Modification of this approach enabled the facile synthesis of the related triazolo-1,4-benzodiazepin-6-ones, also bearing three functional handles. These convenient protocols were used to prepare multi-gram quantities of benzodiazepine analogs as precursors for generating compound libraries for screening campaigns.
- Abeykoon, Gayan A.,Sahn, James J.,Martin, Stephen F.
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- Iron-Catalyzed Radical Activation Mechanism for Denitrogenative Rearrangement Over C(sp3)–H Amination
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An iron-catalyzed denitrogenative rearrangement of 1,2,3,4-tetrazole is developed over the competitive C(sp3)–H amination. This catalytic rearrangement reaction follows an unprecedented metalloradical activation mechanism. Employing the developed method, a wide number of complex-N-heterocyclic product classes have been accessed. The synthetic utility of this radical activation method is showcased with the short synthesis of a bioactive molecule. Collectively, this discovery underlines the progress of radical activation strategy that should find wide application in the perspective of medicinal chemistry, drug discovery and natural product synthesis research.
- Roy, Satyajit,Das, Sandip Kumar,Khatua, Hillol,Das, Subrata,Singh, Krishna Nand,Chattopadhyay, Buddhadeb
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supporting information
p. 8772 - 8780
(2021/03/16)
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- Effective microwave-assisted approach to 1,2,3-triazolobenzo-diazepinones via tandem Ugi reaction/catalyst-free intramolecular azide–alkyne cycloaddition
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A novel catalyst-free synthetic approach to 1,2,3-triazolobenzodiazepinones has been developed and optimized. The Ugi reaction of 2-azidobenzaldehyde, various amines, isocyanides, and acids followed by microwave-assisted intramolecular azide–alkyne cycloaddition (IAAC) gave a series of target heterocyclic compounds in moderate to excellent yields. Surprisingly, the normally required ruthenium-based catalysts were found to not affect the IAAC, only making isolation of the target compounds harder while the microwave-assisted catalyst-free conditions were effective for both terminal and non-terminal alkynes.
- Mazur, Maryna O.,Zhelavskyi, Oleksii S.,Zviagin, Eugene M.,Shishkina, Svitlana V.,Musatov, Vladimir I.,Kolosov, Maksim A.,Shvets, Elena H.,Andryushchenko, Anna Yu,Chebanov, Valentyn A.
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supporting information
p. 678 - 687
(2021/04/09)
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- Regio- and Stereoselective Cascade of β,γ-Unsaturated Ketones by Dipeptided Phosphonium Salt Catalysis: Stereospecific Construction of Dihydrofuro-Fused [2,3-b] Skeletons
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Chiral (dihydro)furo-fused heterocycles are significant structural motifs in numerous natural products, functional materials and pharmaceuticals. Therefore, developing efficient methods for preparing compounds with these privileged scaffolds is an important endeavor in synthetic chemistry. Herein, we develop an effective, modular method by a dipeptide-phosphonium salt-catalyzed regio- and stereoselective cascade reaction of readily available linear β,γ-unsaturated ketones with aromatic alkenes, affording a wide variety of structurally fused heterocyclic molecules in high yields with excellent stereoselectivities. Moreover, mechanistic investigations revealed that the bifunctional phosphonium salt controlled the regio- and stereoselectivities of this cascade reaction, particularly proceeding through the initial ketone α-addition followed by O-participated substitution; and the multiple hydrogen-bonding interactions between Br?nsted acid moieties of catalyst and nitro group of aromatic alkene were crucial in asymmetric induction. Given the generality, versatility, and high efficiency of this method, we anticipate that it will have broad synthetic utilities.
- Chen, Yayun,He, Jiajia,Jiang, Chunhui,Ren, Xiaoyu,Su, Zhishan,Wang, Tianli,Xiao, Kai,Zhang, Hongkui,Zhuang, Cheng
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supporting information
p. 19860 - 19870
(2021/08/06)
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- One-pot, two-step synthesis of 3,4-dihydroquinazoline-2(1H)-thiones from o-azidobenzenealdehydes, aryl amines and carbon disulfide
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A one-pot, two-step method was developed for the synthesis of 3-aryl-3,4-dihydroquinazoline-2(1H)-thiones involving the reductive amination of o-azidobenzaldehydes and aryl amines followed by the Staudinger-aza-Wittig reaction with CS2.
- Zhang, Wensheng,Li, Yan,Zhou, Hongyan,Su, Xiaoli,Zhang, Xiaofeng,Zhang, Wei
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supporting information
(2021/09/02)
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- 1H-1,2,3-triazole embedded Isatin-Benzaldehyde-bis(heteronuclearhydrazones): design, synthesis, antimycobacterial, and cytotoxic evaluation
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Rapid growth of global drug-resistant tuberculosis and urgent requirement for short treatment regimens is stimulating the need for discovery of new TB drugs. In this work, we report the design, synthesis and in vitro antimycobacterial evaluation of a library of isatin-derived bis(heteronuclear hydrazones). Evaluation results revealed that the inclusion of isoniazid core into 1H-1,2,3-triazole tethered isatin-benzaldehydes improved the antimycobacterial activity on tuberculosis mc26230 strain and significantly reduced the cytotoxicity against Vero cells. However, the introduction of semicarbazones/thiosemicarbazones or pyrazine-2-carbohydrazide produced the opposite effects. The compounds with isoniazid and polar-donating groups at the C-5 position of isatin emerged as the most promising conjugates with MIC99?=?0.36?μg/ml. The most active compounds were non-cytotoxic to Vero cells (IC50>100?μg/ml) with selectivity indices >277.
- Johansen, Matt D.,Kremer, Laurent,Kumar, Sumit,Kumar, Vipan,Preeti,Sharma, Bharvi
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- Synthesis of azido-substituted benzaldehydes via SNAr chemistry
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Conditions for the formation of azidobenzaldehydes and azidobenzonitriles using sodium azide in DMSO under typical SNAr conditions are described. This simplifies access to these valuable building blocks compared to the more common sequences reported in the literature. Interestingly, fluorosubstituted aryl ketones and esters do not afford azides, but instead amine products.
- Kafle, Arjun,Yossef, Sandy,Handy, Scott T.
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supporting information
(2020/04/21)
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- Carbon isotope labeling of carbamates by late-stage [11C], [13C] and [14C]carbon dioxide incorporation
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A general procedure for the late-stage [11C], [13C] and [14C]carbon isotope labeling of cyclic carbamates is reported. This protocol allows the incorporation of carbon dioxide, the primary source of carbon-14 and carbon-11 radioisotopes, in a direct, cost-effective and sustainable manner. A disconnection/reconnection strategy, involving ring opening/isotopic closure, was also implemented.
- Del Vecchio, Antonio,Talbot, Alex,Caillé, Fabien,Chevalier, Arnaud,Sallustrau, Antoine,Loreau, Olivier,Destro, Gianluca,Taran, Frédéric,Audisio, Davide
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supporting information
p. 11677 - 11680
(2020/10/19)
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- Gold-catalyzed cyclization of 1-(2′-Azidoaryl) propynols: Synthesis of polysubstituted 4-quinolones
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An unprecedented gold-catalyzed procedure for the synthesis of polysubstituted 4-quinolones from 1-(2′-Azidoaryl) propynols is described. The reaction undergoes an intramolecular nucleophilic attack of the azide group to the Au-Activated triple bonds in a 6-endo-dig manner and subsequent gold-Assisted expulsion of N2 to furnish an α-imino gold carbene intermediate, which triggers a 1,2-carbon migration and finally is converted to 2,3-disubstituted 4-quinolone.
- Wu, Xiang,Zheng, Lang-Lang,Zhao, Li-Ping,Zhu, Cheng-Feng,Li, You-Gui
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supporting information
p. 14769 - 14772
(2019/12/24)
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- Cascade Knoevenagel and aza-Wittig reactions for the synthesis of substituted quinolines and quinolin-4-ols
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A [4 + 2] annulation involving cascade Knoevenagel, aza-Wittig and dehydrofluorination reactions is developed for the synthesis of substituted quinolin-4-ols including analogs bearing CF2H, CF3, and C2F5 groups. This simple and highly efficient method is also applicable for the synthesis of substituted quinolines. A number of reported biologically active compounds can be readily prepared by this one-pot synthesis. Green chemistry metrics analysis of the new reaction processes provided favorable results.
- Zhang, Xiaofeng,Ma, Xiaoming,Qiu, Weiqi,Evans, Jason,Zhang, Wei
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supporting information
p. 349 - 354
(2019/01/28)
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- AgSCF3/Na2S2O8-Promoted Trifluoromethylthiolation/Cyclization of o-Propargyl Arylazides/ o-Alkynyl Benzylazides: Synthesis of SCF3-Substituted Quinolines and Isoquinolines
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A AgSCF3/Na2S2O8-promoted trifluoromethylthiolation/cascade cyclization of o-propargyl arylazides (or o-alkynyl benzylazides) triggered by a carbon-carbon triple bond is reported. This strategy provides the synthesis of valuable SCF3-substituted quinoline and isoquinoline systems via the construction of one C(sp2)-SCF3 bond and one C-N bond within one process.
- Qiu, Yi-Feng,Niu, Yue-Jie,Wei, Xi,Cao, Bao-Qian,Wang, Xi-Cun,Quan, Zheng-Jun
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supporting information
p. 4165 - 4178
(2019/04/10)
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- Pd-Catalyzed Four-Component Sequential Reaction Delivers a Modular Fluorophore Platform for Cell Imaging
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A Pd-catalyzed cascade reaction of four versatile privileged synthons is described. The sequential reaction involves the formation of five new chemical bonds by concatenating three distinct chemical steps. One of the derivatives exhibited absorption in the visible region, fluorescence with a high quantum yield, and excellent photostability. Its application is explored in live cell imaging, which exhibited cytoplasmic and mitochondrial specific staining with no toxicity.
- Ansari, Arshad J.,Joshi, Gaurav,Sharma, Praveen,Maurya, Antim K.,Metre, Ramesh K.,Agnihotri, Vijai K.,Chandaluri, Chanchayya Gupta,Kumar, Raj,Singh, Sandeep,Sawant, Devesh M.
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p. 3817 - 3825
(2019/03/26)
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- Cycloaddition and Cascade Radical Reactions for the Synthesis of Trifluoromethylated Tetrahydrobenzodiazepin-3-ones
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A reaction sequence involving three-component [3 + 2] cycloaddition of azomethine ylides followed by CuI-catalyzed cascade trifluoromethyl radical addition and cyclization is developed for diastereoselective synthesis of fused-tetrahydrobenzodiazepin-3-ones.
- Muthengi, Alex,Erickson, Jon,Muriph, Rachel E.,Zhang, Wei
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p. 5927 - 5935
(2019/05/01)
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- Formation or Cleavage of Rings via Sulfide-Mediated Reduction Offers Background-Free Detection of Sulfide
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A set of three highly selective probes for sulfide detection has been developed. Two novel mechanistic strategies for the detection, including (a) transformation of a pro-fluorophore into an active fluorophore and (b) destruction of a fused ring to activate a fluorophore, have been explored. The structural features of the probes including azido groups ("active" and "latent") and leaving groups (with or without being attached to the fluorophore) have been investigated. During the course of the mechanistic studies, the single-crystal structures of all the probes and the products were obtained. One of the probes proved to be superior in terms of its ability to detect sulfide in pure water via an in situ formation of a fluorophore from a nonfluorescent precursor. These cheap and easy-to-prepare probes offer practical applications of sulfide recognition in environmental water samples and in the ovaries of fruit flies. A detection and quantification method using one of these probes and analysis with a smartphone enabled nonspecialists to detect sulfide reliably.
- Ghosh, Sanjib,Roy, Biswajit,Bandyopadhyay, Subhajit
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p. 12031 - 12039
(2019/10/02)
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- Exploration of Pd-catalysed four-component tandem reaction for one-pot assembly of pyrazolo[1,5-c]quinazolines as potential EGFR inhibitors
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A series of pyrazolo[1,5-c]quinazolines as EGFR inhibitors was designed and synthesized by highly efficient and novel multicomponent route involving Pd-catalyzed tandem one-pot four-component reaction. The reaction proceeds with good functional group tolerance under a simple condition with excellent regioselectivity and high efficiency. Target compounds were screened against cancer cell lines MDA-MB-231, A549 and H1299. Of these, 9b and 10b exhibited superior anticancer activity (IC50 2.5 μM) to erlotinib and gefitinib. Synthetics were able to inhibit EGFR mediated kinase activity, induced ROS in cancer cells promoting mitochondrial mediated apoptosis via halting cell cycle progression at G1 phase.
- Ansari, Arshad J.,Joshi, Gaurav,Yadav, Umesh Prasad,Maurya, Antim K.,Agnihotri, Vijai K.,Kalra, Sourav,Kumar, Raj,Singh, Sandeep,Sawant, Devesh M.
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- Synthesis of Diverse Nitrogen Heterocycles via Palladium-Catalyzed Tandem Azide–Isocyanide Cross-Coupling/Cyclization: Mechanistic Insight using Experimental and Theoretical Studies
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A rapid and elegant tandem azide–isocyanide cross-coupling/cyclization protocol has been developed based on a nitrene transfer reaction. The palladium-catalyzed ligand-free methodology led to the synthesis of three different heterocyclic scaffolds with excellent atom/step/redox economy. Studies based on first-principles-based quantum calculations and control experiments unraveled a concerted process of nitrene transfer reaction on isocyanides, ruling out the metallaaziridine intermediate reported earlier. This finding could pave the way for novel applications of nitrene transfer reactions to generate bioactive heterocycles. (Figure presented.).
- Ansari, Arshad J.,Pathare, Ramdas S.,Maurya, Antim K.,Agnihotri, Vijai K.,Khan, Shahnawaz,Roy, Tapta Kanchan,Sawant, Devesh M.,Pardasani, Ram T.
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supporting information
p. 290 - 297
(2017/12/07)
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- A nickel-catalyzed: Anti -carbometallative cyclization of alkyne-azides with organoboronic acids: Synthesis of 2,3-diarylquinolines
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An anti-carbonickelative cyclization via reversible alkenylnickel E/Z isomerization of 2-azido phenyl propargyl alcohols with aryl boronic acids is achieved using Ni(acac)2 as the catalyst to access 2,3-diaryl quinolines. It represents a rare example of trapping the vinyl metal intermediate with a nitrogen center, a non-carbon center electrophile.
- Ranjith Kumar, Gadi,Kumar, Ravi,Rajesh, Manda,Sridhar Reddy, Maddi
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supporting information
p. 759 - 762
(2018/02/06)
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- Copper-Catalyzed Synthesis of 3-NO2 Quinolines from o-Azidobenzaldehyde and Nitro-olefins and its Application in the Concise Synthesis of Quindolines
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An efficient copper-catalyzed cyclization of o-azidobenzaldehyde and nitro-olefins was developed. This reaction proceeds under solvent-free conditions and displays broad functional group compatibility and affords 3-nitroquinolines in good to excellent yields. The synthetic utility of this strategy is illustrated by the concise construction of quindolines in only three steps, which renders the reaction more practical. (Figure presented.).
- Zheng, Lei,Zeng, Zhigang,Yan, Qiong,Jia, Fengcheng,Jia, Lihui,Chen, Yunfeng
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supporting information
p. 4037 - 4042
(2018/09/14)
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- Photochemistry of ortho -Azidocinnamoyl Derivatives: Facile and Modular Synthesis of 2-Acylated Indoles and 2-Substituted Quinolines under Solvent Control
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The light-promoted potential of ortho -azidocinnamoyl compounds is evaluated for heterocycle synthesis. Depending on the nature of the solvent, 2-acylated indoles were obtained under aprotic conditions, whereas the use of a protic medium led to 2-substituted quinolines. The synthetic significance of this metal-free method is that, by simply changing the solvent, the reaction outcome can be directed towards different key heterocyclic scaffolds.
- Chaabouni,Pinkerton,Abid,Galaup,Chassaing
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supporting information
p. 2614 - 2618
(2017/10/06)
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- Synthesis of 2,3-Disubstituted Quinolines via Ketenimine or Carbodiimide Intermediates
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Cyclopenta[b]quinolines and cyclohexa[b]quinolines were prepared via the reactions of α-diazo ketones with N-(2-cyclopropylidenemethylphenyl)phosphanimines and N-(2-cyclobutylidenemethylphenyl) phosphanimine, respectively. The reaction proceeds in a cascade involving ketenimine formation, 6 π-electron ring closure, and 1,3-alkyl shift. A similar approach was developed for the synthesis of dihydropyrrolo-[2,3-b]quinolines from N-(2-cyclopropylidenemethylphenyl)phosphanimines and isocyanates.
- Zhao, Hongyang,Xing, Yanpeng,Lu, Ping,Wang, Yanguang
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supporting information
p. 15144 - 15150
(2016/10/11)
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- Metal-Free Radical Oxidative Cyclization of o-Azidoaryl Acetylenic Ketones with Sulfinic Acids To Access Sulfone-Containing 4-Quinolones
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A novel one-pot synthesis of sulfone-containing 4-quinolones with easily available sulfinic acids as sulfonylating precursors is described. This reaction is characterized by mild reaction conditions, high functional-group tolerance and amenability to gram-scale synthesis.
- Zhou, Nengneng,Yan, Zhongfei,Zhang, Honglin,Wu, Zhongkai,Zhu, Chengjian
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p. 12181 - 12188
(2016/12/23)
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- Consecutive cycloaddition/SNAr/reduction/cyclization/oxidation sequences: A copper-catalyzed multicomponent synthesis of fused N-heterocycles
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A highly efficient multicomponent domino protocol has been developed for the synthesis of 5-phenyl-[1,2,3]triazolo[1,5-c]quinazolines from simple and readily available (E)-1-bromo-2-(2-nitrovinyl)benzenes, aldehydes, and sodium azide. This elegant domino process involved consecutive [3 + 2] cycloaddition, copper-catalyzed SNAr, reduction, cyclization, and oxidation sequences. Notably, sodium azide acted as a dual nitrogen source in the construction of this novel fused N-heterocycle.
- Jia, Feng-Cheng,Xu, Cheng,Zhou, Zhi-Wen,Cai, Qun,Li, Deng-Kui,Wu, An-Xin
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supporting information
p. 2820 - 2823
(2015/06/16)
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- Diversity Oriented Synthesis of Indoloazepinobenzimidazole and Benzimidazotriazolobenzodiazepine from N1-Alkyne-1,2-diamines
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A one-pot protocol for the diversity oriented synthesis of two N-polyheterocycles indoloazepinobenzimidazole and benzimidazotriazolobenzodiazepine from a common N1-alkyne-1,2-diamine building block is described. The approach involves sequential formation of benzimidazole through cyclocondensation and oxidation, which is followed by the formation of either an azepine ring (through alkyne activation and 6-endo-dig cyclization, 1,2-migration with ring expansion, and re-aromatization), or diazepine and triazole rings through 1,3-dipolar cycloaddition.
- Kumar, Ravi,Arigela, Rajesh K.,Samala, Srinivas,Kundu, Bijoy
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p. 18828 - 18833
(2016/01/26)
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- A simple route to polysubstituted indoles exploiting azide induced furan ring opening
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A straightforward, efficient indole synthesis based on thermolysis of 2-(2-azidobenzyl)furans with attack of the formed nitrene moiety onto the ipso position of furan ring has been developed. The cyclization is accompanied by furan ring opening and affords indoles with a 2-acylvinyl substituent suitable for further modifications.
- Abaev, Vladimir T.,Plieva, Anastasiya T.,Chalikidi, Petrakis N.,Uchuskin, Maxim G.,Trushkov, Igor V.,Butin, Alexander V.
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supporting information
p. 4150 - 4153
(2014/09/30)
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- Synthesis of 2-Substituted Indoles through Visible Light-Induced Photocatalytic Cyclizations of Styryl Azides
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A visible light-induced photocatalytic intramolecular cyclization of styryl azides has been developed in the presence of the ruthenium complex Ru(bpy)3Cl2 (0.5 mol%) as photocatalyst at room temperature. The present photocatalytic strategy features operational simplicity as well as high functional group tolerance, and provides a facile access to various 2-substituted N-free indoles in good to excellent yields. Importantly, the present process can employ sunlight as the light source to afford the corresponding products without loss of reaction efficiency.
- Xia, Xu-Dong,Xuan, Jun,Wang, Qiang,Lu, Liang-Qiu,Chen, Jia-Rong,Xiao, Wen-Jing
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supporting information
p. 2807 - 2812
(2016/02/18)
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- OPHA (oxidation-passerini-hydrolysis-alkylation) strategy: A four-step, one-pot improvement of the alkylative passerini reaction
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Multicomponent reactions are often recognized for their efficiency and convergency, if compared with multistep organic synthesis. Nevertheless, we here demonstrate that a four-step-one-pot approach (named OPHA strategy for the initials of the four steps involved) is not only able to afford compounds that could not be obtained by an alkylative Passerini reaction but also capable of generating them with minimal loss of atoms and high operational simplicity, as in a typical multicomponent approach.
- Moliner, Fabio De,Bigatti, Martina,Banfi, Luca,Riva, Renata,Basso, Andrea
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supporting information
p. 2280 - 2283
(2014/05/06)
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- Facile one-pot assembly of imidazotriazolobenzodiazepines via indium(III)-catalyzed multicomponent reactions
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An operationally simple, one-pot multicomponent reaction has been developed for the assembly of 9H-benzo[f]imidazo[1,2-d][1,2,3]triazolo[1,5-a][1,4] diazepines adorned with three diversification points via an atom-economical transformation incorporating α-diketones, o-azidobenzaldehydes, propargylic amines, and ammonium acetate. This process involves tandem InCl 3-catalyzed cyclocondensation and intramolecular azide-alkyne 1,3-dipolar cycloaddition reactions; optimization data, substrate scope, and mechanistic insights are discussed.
- Nguyen, Huy H.,Palazzo, Teresa A.,Kurth, Mark J.
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supporting information
p. 4492 - 4495
(2013/09/24)
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- One-pot synthesis of indolo[2,3-c]quinolin-6-ones by sequential photocyclizations of 3-(2-azidophenyl)-N-phenylacrylamides
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A one-pot synthesis of indolo[2,3-c]quinolin-6(7H)-ones was achieved by sequential photocyclizations of 3-(2-azidophenyl)-N-phenylacrylamides in moderate to high yields. The reactions proceeded via photochemical cyclization of aryl azides to form N-phenylindol-2-carbamides and subsequent 6π-electrocyclic reaction and oxidative aromatization to afford the corresponding indolo[2,3-c]quinolin-6(7H)-ones. Georg Thieme Verlag Stuttgart · New York.
- Li, Zhanshan,Wang, Weixia,Zhang, Xiaotian,Hu, Congcong,Zhang, Wei
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supporting information
p. 73 - 78
(2013/04/24)
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- Au-catalyzed formation of functionalized quinolines from 2-alkynyl arylazide derivatives
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A new method for converting 2-alkynyl arylazide derivatives into functionalized polysubstituted quinolines following a gold-catalyzed 1,3-acetoxy shift/cyclization/1,2-group shift sequence has been developed. This transformation proceeds under mild reaction conditions, is efficient, and tolerates a large variety of functional groups.
- Gronnier, Colombe,Boissonnat, Guillaume,Gagosz, Fabien
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supporting information
p. 4234 - 4237
(2013/09/12)
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- One-pot, two-step cascade synthesis of quinazolinotriazolobenzodiazepines
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An operationally simple, one-pot, two-step cascade method has been developed to afford quinazolino[1,2,3]triazolo[1,4]benzodiazepines. This unique, atom-economical transformation engages five reactive centers (amide, aniline, carbonyl, azide, and alkyne) and employs environmentally benign iodine as a catalyst. The method proceeds via sequential quinazolinone-forming condensation and intramolecular azide-alkyne 1,3-dipolar cycloaddition reactions. Substrate scope, multicomponent examples, and mechanistic insights are discussed.
- Guggenheim, Kathryn G.,Toru, Hannah,Kurth, Mark J.
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supporting information; scheme or table
p. 3732 - 3735
(2012/09/08)
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- Synthetic studies on indolocarbazoles: Total synthesis of staurosporine aglycon
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A synthesis of staurosporine aglycon and its analogs was achieved in a 28-36% overall yield starting from 2-methylindole. The prominent key steps for the synthesis of the indolocarbazole alkaloids involved electrocyclization and nitrene insertion reactions.
- Rajeshwaran, Ganesan Gobi,Mohanakrishnan, Arasambattu K
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supporting information; experimental part
p. 1418 - 1421
(2011/05/04)
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- Rh2(II)-catalyzed nitro-group migration reactions: Selective synthesis of 3-nitroindoles from β-nitro styryl azides
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Rhodium carboxylate complexes (1 mol %) catalyze the migration of electron-withdrawing groups to selectively produce 3-substituted indoles from β-substituted styryl azides. The relative order of migratorial aptitude for this transformation is ester ? amide H sulfonyl benzoyl ? nitro.
- Stokes, Benjamin J.,Liu, Sheng,Driver, Tom G.
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supporting information; experimental part
p. 4702 - 4705
(2011/05/16)
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- Rhodium-catalyzed synthesis of 2,3-disubstituted indoles from β,β-Disubstituted stryryl azides
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Rings la carte: Rhodium carboxylate complexes catalyze selective cascade reactions to produce a range 2,3-disubstituted indoles from β,β- disubstituted stryryl azides. The selective migration of aryl groups appears to originate from a putative phenonium ion reactive intermediate (see scheme).
- Sun, Ke,Liu, Sheng,Bec, Patryk M.,Driver, Tom G.
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supporting information; experimental part
p. 1702 - 1706
(2011/04/24)
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- A general and efficient approach to 2H-indazoles and 1H-pyrazoles through copper-catalyzed intramolecular N-N bond formation under mild conditions
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A new efficient copper-catalyzed intramolecular amination reaction has been developed to readily synthesise a wide variety of multi-substituted 2H-indazole and 1H-pyrazole derivatives from easily accessible starting materials under mild conditions. A highly selective ligand for estrogen receptor β was prepared in three steps by employing this method. The Royal Society of Chemistry 2011.
- Hu, Jiantao,Cheng, Yongfeng,Yang, Yiqing,Rao, Yu
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supporting information; experimental part
p. 10133 - 10135
(2011/10/09)
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- Synthesis of 2,3,4-tri-substituted 3,4-dihydroquinazolines via tandem nucleophilic addition/epoxy ring-opening cyclization methodology using N-(2-Oxiranylphenyl)carbodiimides with nucleophiles
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N-(2-Oxiranylphenyl)carbodiimides, which were synthesized via an aza-Wittig reaction of the corresponding functionalized iminophosphoranes with aromatic and aliphatic isocyanates, underwent O-, S-, C-, or N-nucleophilic addition onto a cumulene, followed by an epoxy ring-opening cyclization with the newly formed NH-nucleophile in a one-pot reaction to furnish 2,3-disubstituted 4-(hydroxymethyl)-3,4-dihydroquinazolines in a highly stereospecific manner. The Japan Institute of Heterocyclic Chemistry.
- Saito, Takao,Ote, Tatsuya,Shiotani, Masahiro,Kataoka, Hiroko,Otani, Takashi,Kutsumura, Noriki
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p. 305 - 311
(2011/04/16)
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- Revisiting the thermal decomposition of five ortho-substituted phenyl azides by calorimetric techniques
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The thermal decomposition (TD) of 2-azidophenylmethanol (1), 2-azidobenzenecarbaldehyde (2), 1-(2-azidophenyl)-1-ethanone (3), (2-azidophenyl)(phenyl)methanone (4) and 1-azido-2-nitrobenzene (5) was analysed by DSC, TG and C80 calorimetric techniques under both oxidative and non-oxidative conditions. The TD of these azides in solution is well known to give the corresponding benzoxazoles, generally in good yields, with the exception of azide 1. When both the outcomes from the solid phase and in 'solution phase' TD reactions combined with the results from EI-MS experiments were considered, sufficient information was available to estimate the azides intrinsic molecular reactivity (MIR).
- Cardillo, Paolo,Gigante, Lucia,Lunghi, Angelo,Zanirato, Paolo
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p. 191 - 198
(2010/08/04)
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- Intramolecular Fe(II)-Catalyzed N-O or N-N bond formation from aryl azides
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(Figure presented) Iron(II) bromide catalyzes the transformation of aryl and vinyl azides with ketone or methyl oxime substituents into 2,1-benzisoxazoles, indazoles, or pyrazoles through the formation of an N-O or N-N bond. This transformation tolerates a variety of different functional groups to facilitate access to a range of benzisoxazoles or indazoles. The unreactivity of the Z-methyloxime indicates that N-heterocycle formation occurs through a nucleophilic attack of the ketone or oxime onto an activated planar iron azide complex.
- Stokes, Benjamin J.,Vogel, Carl V.,Urnezis, Linda K.,Pan, Minjie,Driver, Tom G.
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supporting information; experimental part
p. 2884 - 2887
(2010/08/21)
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- New efficient synthesis of pyrimido[1,6-c]quinazolin-4-ones by a Biginelli 3CC/Staudinger/aza-Wittig sequence
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Dihydropyrimidinone azides 1, obtained from trimethylsilyl chloride-catalyzed Biginelli reaction of 2-azidobenzaldehyde, ethyl acetoacetate, and urea (or thiourea) at room temperature, reacted with triphenylphosphine to give iminophosphorane 2. A tandem aza-Wittig reaction of iminophosphorane 2 with isocyanate, acyl chloride or CS2 in the presence of K2CO3 or NEt3 generated pyrimido[1,6-c]quinazolin-4-ones 4, 6 or 8 in moderate to good yield.
- Li, Wen-Jing,Liu, Shuai,He, Ping,Ding, Ming-Wu
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experimental part
p. 8151 - 8159
(2010/10/21)
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- A method for the synthesis of substituted quinolines via electrophilic cyclization of 1-azido-2-(2-propynyl)benzene
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(Chemical Equation Presented) A new and efficient strategy for the synthesis of substituted quinolines via electrophilic cyclization is developed. The intramolecular cyclization of 1-azido-2-(2-propynyl)benzene 1 proceeds smoothly in the presence of electrophilic reagents (I2, Br 2 , ICl, NBS, NIS, and HNTf2) in CH3NO 2 at room temperature or in the presence of catalytic amounts of AuCl3/AgNTf2 in THF at 100 °C to afford the corresponding quinolines 2 in good to high yields. In the case of the electrophilic reagents, E of 2 is either I, Br, orH, depending on the reagent type, while E of 2 is H in the case of the electrophilic catalyst. 2010 American Chemical Society.
- Huo, Zhibao,Gridnev, Ilya D.,Yamamoto, Yoshinori
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supporting information; experimental part
p. 1266 - 1270
(2010/04/29)
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- A new modular and flexible approach to [1,2,3]triazolo[1,5-a][1,4]benzodiazepines
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A new synthetic route for the access to [1,2,3]triazolo[1,5-a][1,4]benzodiazepines and other derivatives is described. This strategy is based on the cycloaddition of 2-oxoalkylidenephosphoranes to o-functionalized aryl azides followed by the reaction of the corresponding triazole intermediate with amines. This new approach presents unique properties such as regioselectivity, modularity, mild reaction conditions, and high yields.
- Alajarín, Mateo,Cabrera, José,Pastor, Aurelia,Villalgordo, José M.
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p. 3495 - 3499
(2008/02/06)
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- Synthesis of fused triazolo-imidazole derivatives by sequential van Leusen/alkyne-azide cycloaddition reactions
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A facile synthesis of fused triazolo imidazole derivatives by a van Leusen/alkyne-azide cycloaddition synthetic sequence is reported. The two-step reaction sequence generates compounds of significant molecular complexity from simple starting materials in an expedient fashion with good overall yields.
- Gracias, Vijaya,Darczak, Daria,Gasiecki, Alan F.,Djuric, Stevan W.
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p. 9053 - 9056
(2007/10/03)
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- Synthesis of 2-nitroindoles via the Sundberg indole synthesis
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A three-step sequence has been developed for converting o-nitrobenzaldehydes into 2-nitroindoles. The key step involves the thermolysis of 2-(o-azidophenyl)nitroethylene (10) in xylenes which gives 2-nitroindole (4) in 54% yield, akin to the classic Sundberg indole synthesis. This procedure has also been utilized to synthesize 5,6-dimethoxy-2-nitroindole (14).
- Pelkey, Erin T.,Gribble, Gordon W.
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p. 5603 - 5606
(2007/10/03)
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- SYNTHETIC STUDIES TOWARDS CYSTODYTIN A:THE PREPARATION OF NOVEL CYSTODYTIN CONGENERS
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A sequence involving a modified Knoevenagel-Stobbe pyridine synthesis, and an unusual intramolecular reaction between a quinone and an azide, permits expeditious assembly of the ring system of the cystodytin alkaloids.
- Ciufolini, Marco A.,Byrne, Norman E.
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p. 5559 - 5562
(2007/10/02)
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- SYNTHETIC APPROACHES TOWARD FR-900482. I. STEREOSELECTIVE SYNTHESIS OF A PENTACYCLIC MODEL COMPOUND.
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An efficient synthesis of a pentacyclic compound 18 possessing all the necessary handles to construct the unique skeleton of antitumor antibiotic FR-900482 1 is described.
- Fukuyama, Tohru,Goto, Shunsuke
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p. 6491 - 6494
(2007/10/02)
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- Pyrolysis of Aryl Azides. IX. Azomethines as Weak Neighbouring Groups
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The following rates of pyrolysis (relative to azidobenzene at 120 deg C) have been measured in decalin solution: 2-azidobenzaldehyde, 28.8; 2-azidobenzylideneaniline, 59.5; 2-azidobenzaldehyde phenylhydrazone, 8.9; 2-azidobenzaldehyde oxime O-methyl ether, 1.3; 2-azidoacetophenone oxime O-methyl ether, 23.4; 2-azidobenzophenone phenylhydrazone, 9.7.It is argued that these relative rates are largely determined by the extent to which the ortho substituent is in the reactive conformation for an electrocyclic process.Indazoles substituted on N2 are isolated from pyrolysis of those azides with ortho-azomethine substituents.
- Dyall, Leonard K.,Holmes, Ann-Louise
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p. 1677 - 1686
(2007/10/02)
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