- Light-Enabled Radical 1,4-Aryl Migration Via a Phospho-Smiles Rearrangement
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Rearrangement reactions in organic chemistry are attractive strategies to build efficiently complex scaffolds, in just one step, from simple starting materials. Among them, aryl migrations are certainly one of the most useful and straightforward rearrangement for building attractive carbon-carbon bonds. Of note, anionic aryl migration reactions have been largely described compared to their radical counterparts. Recently, visible-light catalysis has proven its efficiency to generate such radical rearrangements due to the concomitant loss of a particle (often CO2 or SO2), which is the driving-force of the reaction. Here, we disclose a Smiles-type rearrangement, triggered by a phosphorus-containing unit (arylphosphoramidate), therefore called "phospho-Smiles"rearrangement, allowing a Csp2-Csp2 bond formation thanks to a 1,4-aryl migration reaction. In addition, combining this approach with a radical hydroamination/amination reaction produces an amination/phospho-Smiles cascade particularly attractive, for instance, to investigate the synthesis of the phthalazine core, a scarcely described scaffold of interest for medicinal chemistry projects.
- De Abreu, Maxime,Belmont, Philippe,Brachet, Etienne
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p. 3758 - 3767
(2021/02/01)
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- Tandem 6π-Azatriene Electrocyclization of Fused Amino-cyclopentenones: Synthesis of Functionalized Pyrrolo- And Indolo-quinoxalines
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A tandem 6π-azacyclization approach for the synthesis of diversified pyrrolo/indolo[1,2-a]quinoxalines from amino-cyclopentenones has been developed. The reaction proceeds through a trifluoroacetic-acid-mediated 6π-electrocyclization and concomitant opening of the cyclopentenone ring. The advantageous features of the developed chemistry include transition-metal-free conditions, operational simplicity, and a broad substrate scope. Further X-ray crystallographic studies confirm the assigned structures of the fused heterocycles.
- Saini, Kapil Mohan,Saunthwal, Rakesh K.,Kumar, Ankit,Verma, Akhilesh K.
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supporting information
p. 7586 - 7591
(2021/10/12)
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- Transition-metal-free oxidative cyclization reaction of enynals to access pyrane-2-one derivatives
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A novel and efficient metal-free C-H functionalization of enynals is developed to synthesize α-pyrone derivatives via the formation of two C-O bonds. In this project, K2S2O8 has been introduced as an efficient oxygen source and C-H functionalization agent in regioselective oxidative cyclization reaction with a relatively broad substrate scope.
- Abbasi Kejani, Alireza,Ansari, Farzaneh,Armaghan, Mahsa,Balalaie, Saeed,Frank, Walter,Jafarpour, Farnaz,Khosravi, Hormoz
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p. 4263 - 4267
(2021/05/31)
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- Na2S·9H2O mediated facile synthesis of 1,3-dihydrofuro[3,4-b]quinoline derivatives via domino reduction approach
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A simple, highly efficient method for synthesis of 1,3-dihydrofuro[3,4-b]quinoline is described by the reaction of o-arylalkynyl quinoline aldehydes with Na2S·9H2O via domino reduction approach. The method is simple and proceeds under mild condition under an air atmosphere to give 1,3-dihydrofuro[3,4-b]quinoline in good to excellent yields. The beauty of the reaction is cyclization as well as reduction has been taken place in the same reaction pot. Also the conversion of aldehyde into primary alcohol has been discussed under the same reaction condition.
- Singh, Rashmi,Gupta, Tanu,Sharma, Vishal Prasad,Singh, Radhey M.,Tewari, Ashish Kumar
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supporting information
(2021/09/22)
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- Synthesis of cyclopentaquinolinone and cyclopentapyridinone from: Ortho-alkynyl-N-arylaldehyde via superbase-promoted C-N, C-O and C-C bond formation
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An environmentally benign, transition metal-free, superbase-mediated intramolecular annulation of o-alkynylaldehydes with primary amines forms highly functionalized amino-substituted cyclopentaquinolinones and cyclopentapyridinones via C-N, C-C, and CO bond formation. Contrary to the traditional approaches of ring closures, a different mode of annulation is disclosed. The protocol involves the in situ generations of imine intermediate followed by potassium hydroxide-promoted intramolecular cyclization and subsequent dimethyl sulfoxide induced dehydrogenation leads to the formation of N-heterocycles. X-ray crystallographic studies support the assigned structures of the amino-fused N-heterocycles.
- Saini, Kapil Mohan,Saunthwal, Rakesh K.,Sushmita,Verma, Akhilesh K.
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supporting information
p. 5594 - 5601
(2020/08/21)
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- Catalytic formal [4 + 1] isocyanide-based cycloaddition: An efficient strategy for the synthesis of 1: H -cyclopenta [b] quinolin-1-one derivatives
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An unprecedented catalytic isocyanide-based cycloaddition of alkyl and aryl isocyanides with (Z)-2-(2-hydroxy-2-alkylvinyl)quinoline-3-carbaldehydes was developed for the direct and efficient synthesis of 1H-cyclopenta[b]quinolin-1-one derivatives. On the
- Motaghi, Milad,Khosravi, Hormoz,Balalaie, Saeed,Rominger, Frank
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p. 275 - 282
(2019/01/10)
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- Iodine mediated: In situ generation of R-Se-I: Application towards the construction of pyrano[4,3- b] quinoline heterocycles and fluorescence properties
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In this paper, we report the iodine mediated in situ generation of R-Se-I and further its application towards the construction of pyrano[4,3-b]quinolin-1-one derivatives. The structural elaboration of 1-chloro-8-methyl-3-phenylbenzo[b][1,6]naphthyridine 6 was successfully achieved by Sonogashira, Suzuki coupling and dehalogenation reactions. Finally, the synthesized compounds 4a, 5a, 5b, 6, and 7a-7c were studied for photophysical properties including UV-absorption, fluorescence, and quantum yield studies. The synthesized pyranoquinoline derivatives showed λmax, Fmax and Φf values in the range of 391-447 nm, 436-486 nm and 0.004-0.301, respectively in chloroform solvent.
- Win, Khin Myat Noe,Sonawane, Amol D.,Koketsu, Mamoru
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supporting information
p. 9039 - 9049
(2019/10/28)
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- Silver-Catalyzed Domino Hydroarylation/Cycloisomerization Reactions of 2-Alkynylquinoline-3-carbaldehydes: Access to (Hetero)arylpyranoquinolines
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A silver trifluoromethanesulfonate catalyzed efficient access to the indolylpyranoquinoline scaffold is reported. Starting from 2-alkynylquinoline-3-carbaldehyde units with various substitution patterns on the quinoline and alkynyl parts, the use of silver trifluoromethanesulfonate (10 mol%) in 1,2-dichloroethane allowed a domino hydroarylation/cycloisomerization reaction, generating (hetero)aryl-functionalized pyranoquinolines. The heteroarenes that were used are N-methylindole (18 compounds, 67-100%), indole, and 2-methylindole (4 compounds, 36-89%), and the reaction was also compatible to a lesser extent with arenes such as pyrroles (5 compounds, 43-90%), 1,3,5-trimethoxybenzene, and 3-methylbenzofuran.
- Bontemps, Alexis,Mariaule, Ga?lle,Desbène-Finck, Stéphanie,Helissey, Philippe,Giorgi-Renault, Sylviane,Michelet, Véronique,Belmont, Philippe
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p. 2178 - 2190
(2016/07/15)
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- FeCl3·6H2O-catalyzed facile and efficient synthesis of pyrano[4,3-b]quinolines and isochromenes
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An inexpensive 1 mol % FeCl3·6H2O reagent has been developed for the synthesis of 1,3-disubstituted 1H-pyrano[4,3-b]quinolines from o-arylethnylquinonylmethanol via 6-endo-dig cyclization of alcoholic -OH onto alkynes in good to excellent yields. The reaction conditions were successfully exploited on primary and tertiary alcohol analogs. The reagent was further generalized with the aromatic alcohol analogs providing the synthesis of isochromenes in good yields. The enhancement in the reaction rates and yields from primary to secondary to tertiary alcohols could be attributed to inductive effect of alkyl groups which enhanced the nucleophilicity of hydroxyl group and accelerated the cyclization mode.
- Asthana, Mrityunjaya,Singh, Jay Bahadur,Singh, Radhey M.
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p. 615 - 618
(2016/01/20)
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- Efficient synthesis via azide-alkyne Huisgen [3+2] cycloaddition reaction and antifungal activity studies of novel triazoloquinolines
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New functionalized 1,2,3-triazoloquinolines were achieved by intramolecular azide-alkyne Huisgen [3+2] cycloaddition. These derivatives were synthesized via the key Baylis-Hillman adduct under mild, neutral conditions in short duration and consistently go
- Saravanan, Nagarajan,Arthanareeswari, Maruthapillai,Kamaraj, Palanisamy,Sivakumar, Bitragunta
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p. 5379 - 5388
(2015/07/08)
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- Molecular iodine-mediated reaction of 2-(2-phenylethynyl)-Morita-Baylis-Hillman adducts: An easy route to naphthyl ketones and iodo-substituted isochromenes
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The molecular iodine-promoted reaction of 2-(2-phenylethynyl)-Morita-Baylis-Hillman adducts is reported. In the presence of I2, naphthyl ketone derivatives are produced, whereas in the presence of I2/K3PO4, iodo-substituted isochromene derivatives are produced. This journal is
- Janreddy, Donala,Kavala, Veerababurao,Kotipalli, Trimurtulu,Rajawinslin,Kuo, Chun-Wei,Huang, Wen-Chang,Yao, Ching-Fa
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supporting information
p. 8247 - 8256
(2015/01/08)
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- Platinum-catalyzed tandem cycloisomerization reaction of benzoendiynyl esters: Regioselective long-range 1,5-Acyl migration
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A PtII-catalyzed intramolecular chemo- and regioselective pentannulation/long-range 1,5-acyl migration reaction is described. This cascade cycloisomerization protocol produces a wide variety of benzofulvene diketones in good to excellent yields with exclusively the Z configuration of the exocyclic double bond of the final product. The 18O isotope experiment together with 13C NMR, HRMS, and HMBC analyses confirmed an interesting long-range acyl rearrangement process in this transformation.
- Chen, Zhiyuan,Jia, Xuegong,Huang, Jiapian,Yuan, Jianjun
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p. 10674 - 10681
(2015/02/19)
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- Au(III)-catalyzed regio-and stereoselective tandem synthesis of oxazolo fused naphthyridines and isoquinolines from o-alkynylaldehydes
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An efficient tandem approach for the regio-and stereoselective synthesis of oxazolo-fused naphthyridines 3a-g, 3i-l and isoquinolines 3h, 3m via the reaction of o-alkynylaldehydes 1a-i with chiral amino alcohols 2a-c under mild reaction conditions is described. The stereochemistry and structures of the products were assigned via NOESY and X-ray crystallographic studies.
- Jha, Rajeev Ranjan,Danodia, Abhinandan Kumar,Kumar, Sushil,Verma, Akhilesh Kumar
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supporting information
p. 610 - 615
(2014/01/23)
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- Formation of condensed 1 H-pyrrol-2-ylphosphonates and 1,2-dihydropyridin- 2-ylphosphonates via Kabachnik-fields reaction of acetylenic aldehydes and subsequent 5-exo-dig or 6-endo-dig cyclizations
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Kabachnik-Fields reactions of various carbocyclic or heterocyclic acetylenic aldehydes together with subsequent Lewis acid catalyzed cyclizations have been studied. It was found that 5-exo-dig versus 6-endo-dig cyclization mode strongly depends on the structure of starting materials. Thus, nonaromatic acetylenic α-anilinomethylphosphonates underwent gold(III)-catalyzed or iodine-mediated 5-exo-dig cyclization to 1H-pyrrol-2-ylphosphonates. In contrast, electron-withdrawing heteroaromatic substrates formed 1,2-dihydropyridin-2-ylphosphonate ring containing materials via an exclusive 6-endo-dig ring-closure process. The dual mode of cyclization is possible only for α-amino (2-alkynylphenyl)methylphosphonates containing a benzene ring.
- Buk?naitienè, Rita,Urbanaitè, Aurelija,?ikotienè, Inga
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p. 6532 - 6553
(2014/08/05)
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- On water: Silver-catalyzed domino approach for the synthesis of benzoxazine/oxazine-fused isoquinolines and naphthyridines from o-alkynyl aldehydes
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An operationally simple domino approach for the silver-catalyzed synthesis of oxazine/benzoxazine-fused isoquinolines 5a-q and naphthyridines 6a-v by the reaction of o-alkynyl aldehydes 3a-aa with amines having embedded nucleophiles 4a-d under mild reacti
- Verma, Akhilesh K.,Choudhary, Deepak,Saunthwal, Rakesh K.,Rustagi, Vineeta,Patel, Monika,Tiwari, Rakesh K.
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p. 6657 - 6669
(2013/07/26)
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- Silver-catalyzed tandem synthesis of naphthyridines and thienopyridines via three-component reaction
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An efficient approach for the silver-catalyzed regioselective tandem synthesis of highly functionalized 1,2-dihydrobenzo[1,6]naphthyridines 6a-z and 7a-e by the reaction of ortho-alkynylaldehydes 3a-n with amines 4a-d and ketones 5a-c/active methylene com
- Verma, Akhilesh K.,Kotla, Siva K. Reddy,Choudhary, Deepak,Patel, Monika,Tiwari, Rakesh K.
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p. 4386 - 4401
(2013/06/05)
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- Convenient synthesis of benzo[b]pyrazolo[5,1-f][1,6]naphthyridines by silver triflate catalyzed three-component reaction of 2-alkynyl-3- formylquinolines, tosylhydrazine and carbonyl compounds
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Benzo[b]pyrazolo[5,1-f][1,6]naphthyridines were prepared by silver triflate catalyzed one-pot cyclization of tosylhydrazine, carbonyl compounds and 2-alkynyl-3-formylquinolines, which are available by Sonogashira reaction of 2-chloro-3-formylquinoline.
- Zahid, Muhammad,Iaroshenko, Viktor O.,Saghyan, Ashot S.,Fischer, Christine,Langer, Peter
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p. 3451 - 3458
(2013/04/24)
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- An economical nucleophilic route toward facile synthesis of pyrano[4,3-b]quinolin-1-ones via 6-endo-dig cyclization of o-alkynylquinoline esters
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Metal-free facile synthesis of pyrano[4,3-b]quinoline-1-ones is described from methyl 2-arylethynylquinoline-3-carboxylates via intramolecular cyclization in excellent yields. The cyclization reactions are facilitated using cheap and easily available KOH base in MeOH. The reaction conditions did not require dry solvent, inert atmosphere, and avoid further column chromatography purification of the products. These compounds could be further used as building blocks for the synthesis of 2H-benzo[b][1,6]naphthyridin-1-one and 1-chloro-benzo[b][1,6] naphthyridines.
- Sharma, Neha,Asthana, Mrityunjaya,Nandini, Durgesh,Singh,Singh, Radhey M.
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p. 1822 - 1829
(2013/04/10)
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- An efficient synthesis of indol-3-yl benzonaphthyridines via copper(II) triflate-catalyzed heteroannulation
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An efficient and convenient method for the synthesis of indol-3-yl benzo[b][1,6]- and benzo[c][2,7]naphthyridines via copper(II) triflate-catalyzed heteroannulation is reported. This method gives new analogues of indole containing benzonaphthyridines from
- Prakash,Nagarajan, Rajagopal
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supporting information
p. 3635 - 3638
(2013/07/05)
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- A facile and efficient synthesis of 1-trichloromethyl-1,2-dihydrobenzo [b] [1,6] naphthyridines via three-component reaction among 2-alkynylquinoline-3- carbaldehydes, primary amines, and chloroform
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A three-component reaction among 2-alkynylquinoline-3-carbaldehydes, primary amines, and chloroform leading to novel 1-(trichloromethyl)-1,2- dihydrobenzo [b] [1,6] naphthyridines was developed using microwave initiation in an absence of any catalysts. Th
- Buksnaitiene, Rita,Cikotiene, Inga
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body text
p. 87 - 92
(2012/08/08)
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- AgI-catalyzed cascade strategy: Regioselective access to diversely substituted fused benzimidazo[2,1-a]isoquinolines, naphthyridines, thienopyridines, and quinoxalines in water
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An environmentally benign and operationally simple one-pot approach to the regioselective tandem synthesis of diversely substituted fused benzimidazo[2,1-a]isoquinolines, naphthyridines, thienopyridines, and quinoxalines from o-alkynylaldehydes and arylamines with tethered nucleophiles using AgI as catalyst in water is described. The reaction showed selective N-C bond formation on the more electrophilic alkynyl carbon, resulting in the regioselective 6-endo-dig cyclized products in good to excellent yields. The proposed mechanistic pathway for the synthesis of fused heterocycles proceeding through formation of ring A prior to ring B, which formed through a second intramolecular attack of the nitrogen onto the alkynyl carbon, was supported by mechanistic experiments and X-ray crystallographic studies of isolated intermediate U and cyclized product 5a. Comparative experiments showed the viability of intramolecular nucleophilic attack over intermolecular attack of an external nucleophile. This catalytic, green protocol has been efficiently applied for the bis-tandem cyclization in water. An eco-friendly, one-pot cascade approach to benzimidazoles and quinoxalines in water using AgNO 3 as catalyst from o-alkynyl aldehydes and amines with tethered nucleophiles, has been developed. Selective 6-endo-dig regioselectivity and structural diversity are accomplished in good yields with a range of substrates. X-ray crystallographic studies and mechanistic experiments are also presented. Copyright
- Rustagi, Vineeta,Tiwari, Rakesh,Verma, Akhilesh Kumar
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supporting information
p. 4590 - 4602
(2012/11/07)
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- Study on the reactions of acetylenic aldehydes with dimethyl phosphite in basic media: Phosphonate-phosphate rearrangement versus 5-exo-dig cyclization reactions
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Tandem reactions of various acetylenic aldehydes with dimethyl phosphite in basic media were investigated. It was shown that in the case of a non-activated triple bond of the starting materials, the well-known Pudovik reaction followed by a subsequent phosphonate-phosphate rearrangement took place. On the other hand when the triple bond of the starting materials is activated by electron-withdrawing heterocycles, a smooth and regioselective tandem 5-exo-dig cyclization reactions becomes possible.
- Cikotiene, Inga,Buksnaitiene, Rita
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p. 2719 - 2726
(2013/01/15)
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- Base-free NIS promoted electrophilic cyclization of alkynes: An efficient synthesis of iodo substituted pyrano[4,3-b]quinolines
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A simple and mild procedure for the synthesis of iodo substituted 1H-pyrano[4,3-b]quinolines has been achieved using NIS reagent in the absence of base from 2-alkynylquinoline-3-carboxaldehydes via intramolecular electrophilic cyclization onto alkynes in good to excellent yields in a short duration of time. The reactions proceeded smoothly in a normal solvent in aerobic atmosphere at room temperature. The presence of substituent at either quinoline or alkyne moieties did not show effect on reaction rate of cyclization. The palladium-catalyzed transformations of iodo group to C-C bond are also discussed. Copyright
- Singh, Bhawana,Chandra, Atish,Singh, Seema,Singh, Radhey M.
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scheme or table
p. 505 - 511
(2011/03/18)
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- Pyrano[4,3-b]quinolines library generation via iodocyclization and palladium-catalyzed coupling reactions
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Synthesis of a 80-member library of novel pyrano[4,3-b]quinolines in solution-phase is reported. The key intermediate, 4-iodopyrano[4,3-b]quinolines were synthesized by the electrophilic iodocyclization of corresponding ortho-alkynyl aldehydes in good to
- Aggarwal, Trapti,Imam, Maryam,Kaushik, Naveen K.,Chauhan, Virander S.,Verma, Akhilesh K.
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scheme or table
p. 530 - 536
(2011/11/06)
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- Iodine-catalyzed and solvent-controlled selective electrophilic cyclization and oxidative esterification of ortho-alkynyl aldehydes
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4-Iodo-pyrano[4,3-b]quinolines and ortho-alkynyl esters were synthesized selectively from ortho-alkynyl aldehydes by an iodine-catalyzed and solvent controlled reaction.
- Verma, Akhilesh Kumar,Aggarwal, Trapti,Rustagi, Vineeta,Larock, Richard C.
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supporting information; experimental part
p. 4064 - 4066
(2010/09/05)
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- Iodine-mediated solvent-controlled selective electrophilic cyclization and oxidative esterification of o-alkynyl aldehydes: An easy access to pyranoquinolines, pyranoquinolinones, and isocumarins
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Chemoselective behavior of iodine in different solvents in the electrophilic iodocyclization of o-alkynyl aldehydes is described. o-Alkynyl aldehydes 3a-t on reaction with I2 in CH2Cl2 with appropriate nucleophiles provides pyrano[4,3-b]quinolines 4a-f, via formation of cyclic iodonium intermediate Q; however, using alcohols as a solvent as well as nucleophile, o-alkynyl esters 5a-y were obtained selectively in good to excellent yields via formation of hypoiodide intermediate R. Subsequently, o-alkynyl esters were converted in to pyranoquinolinones 6a-i and isocoumarin 6j by electrophilic iodocyclization. This developed oxidative esterification provides a novel access for the chemoselective synthesis of esters 5q-u from aldehydes 3n-p without oxidizing primary alcohol present in the substrate.
- Verma, Akhilesh K.,Rustagi, Vineeta,Aggarwal, Trapti,Singh, Amit P.
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scheme or table
p. 7691 - 7703
(2010/12/29)
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- Copper-free Sonogashira coupling of 2-chloroquinolines with phenyl acetylene and quick annulation to benzo[b][1,6]naphthyridine derivatives in aqueous ammonia
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An efficient copper-free Sonogashira coupling of 2-chloroquinolines with phenyl acetylene to 2-ethynylquinolines is described. We further discussed the one pot facile annulation of 2-alkynylquinoline-3-carboxaldehydes to 3-phenylbenzo[b][1,6]naphthyridines in aqueous ammonia in excellent yield.
- Chandra, Atish,Singh, Bhawana,Upadhyay, Shraddha,Singh, Radhey M.
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experimental part
p. 11680 - 11685
(2009/04/11)
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- A new route to acridines: Pauson-Khand reaction on quinoline-bearing 1-En-7-ynes leading to novel tetrahydrocyclopenta[c]acridine-2,5-diones
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Efficient Pauson-Khand reactions on quinolines bearing 1-en-7-ynes features gave tetrahydrocyclopenta[c]acridine derivatives. The quinoline intermediates were obtained in two steps: a Sonogashira reaction with functionalized alkynes (TMS, Bu, Ph, CHB
- Patin, Amaury,Belmont, Philippe
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p. 2400 - 2406
(2007/10/03)
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