- Synthesis and photophysical insights of new fused N-heterocyclic derivatives with isoquinoline skeleton
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Six new fused isoquinoline based compounds (compounds 5a–c with pyrrolo[2,1-a] isoquinoline structure and compounds 6a–c with imidazo[2,1-a]isoquinoline skeleton) have been synthesized using the [3 + 2] cycloaddition of the several in situ generated cycloimmonium ylides to ethyl propiolate or ethyl cyanoformate. All the synthesized compounds have been investigated in solution by UV–VIS absorption, steady and time-resolved fluorescence methods. The effect of the substituents on the spectral characteristics has been demonstrated. These derivatives displayed an intense emission between 360 and 420 nm. The emission quantum yields (Φ = 0.54–0.64) of pyrroloisoquinoline derivatives in dimethylsulfoxide (DMSO) were significantly higher than those of imidazoquinolines (0.03–0.16). The fluorescence decay of isoquinoline derivatives follows a biexponential law. A noticeable response of these isoquinoline derivatives to sodium hydroxide was observed.
- Airinei, Anton,Craciun, Anda M.,Danac, Ramona,Gherasim, Carmen,Isac, Dragos Lucian,Mangalagiu, Ionel I.,Nicolescu, Alina,Tigoianu, Radu
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- Unprecedented access to functionalized pyrrolo[2,1-a]isoquinolines from the domino reaction of isoquinolinium ylides and electrophilic benzannulated heterocycles
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We have come across an unexpected reaction between electrophilic indoles and isoquinolinium methylides for accessing functionalized pyrrolo[2,1-a]isoquinolines. The reaction was found in general to yield the products in good yields. We also observed the f
- Babu, Sheba Ann,A. R., Rajalekshmi,P. R., Nitha,Omanakuttan, Vishnu K.,P., Rahul,Varughese, Sunil,John, Jubi
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- Unified Synthesis of Azepines by Visible-Light-Mediated Dearomative Ring Expansion of Aromatic N-Ylides
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Herein, we report a unified approach to azepines by dearomative photochemical rearrangement of aromatic N-ylides. Deprotonation of quaternary aromatic salts with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or N,N,N′,N'-tetramethylquanidine (TMG) under visible light irradiation provides mono- and polycyclic azepines in yields up to 98%. This ring-expansion presents a new mode of access to functionalized azepines from N-heteroarenes using two straightforward steps and simple starting materials.
- Mailloux, Matthew J.,Fleming, Gabrielle S.,Kumta, Shruti S.,Beeler, Aaron B.
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supporting information
p. 525 - 529
(2021/01/26)
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- -Annulation of gem-Difluoroalkenes and Pyridinium Ylides: Access to Functionalized 2-Fluoroindolizines
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A [3 + 2]-annulation of gem-difluoroalkenes and pyridinium ylides was developed employing ambient air as the sole oxidant in an open-vessel manner, affording a series of multifunctionalized 2-fluoroindolizines in moderate to good yields. In this reaction, gem-difluoroalkene acts as a C2 synthon and entirely avoids the competitive addition-elimination process, which provides facile access to 2-fluoroindolizines.
- Zhang, Jun-Qi,Hu, Dandan,Song, Jinyu,Ren, Hongjun
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p. 4646 - 4660
(2021/04/06)
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- Diversified Transformations of Tetrahydroindolizines to Construct Chiral 3-Arylindolizines and Dicarbofunctionalized 1,5-Diketones
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Enantioselective diverse synthesis of a small-molecule collection with structural and functional similarities or differences in an efficient manner is an appealing but formidable challenge. Asymmetric preparation and branching transformations of tetrahydroindolizines in succession present a useful approach to the construction of N-heterocycle-containing scaffolds with functional group, and stereochemical diversity. Herein, we report a breakthrough toward this end via an initial diastereo- A nd enantioselective [3 + 2] cycloaddition between pyridinium ylides and enones, following diversified sequential transformations. Chiral N,N′-dioxide-earth metal complexes enable the generation of optically active tetrahydroindolizines in situ, across the strong background reaction for racemate-formation. In connection with deliberate sequential transformations, involving convenient rearomatic oxidation, and light-active aza-Norrish II rearrangement, the tetrahydroindolizine intermediates were converted into the final library including 3-arylindolizine derivatives and dicarbofunctionalized 1,5-dicarbonyl compounds. More importantly, the stereochemistry of four-stereogenic centered tetrahydroindolizine intermediates could be efficiently transferred into axial chirality in 3-arylindolizines and vicinal pyridyl and aryl substituted 1,5-diketones. In addition, densely functionalized cyclopropanes and bridged cyclic compounds were also discovered depending on the nature of the pyridinium ylides. Mechanism studies were involved to explain the stereochemistry during the reaction processes.
- Feng, Xiaoming,He, Qianwen,Liu, Xiaohua,Pan, Chenjing,Su, Zhishan,Wu, Zhikun,Zhang, Dong,Zhou, Yuqiao
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supporting information
p. 15975 - 15985
(2020/10/18)
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- External oxidant-free oxidation/[3+2] cycloaddition/aromatization cascade: Electrochemical synthesis of polycyclic N-heterocycles
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Here, we describe an efficient and environmentally friendly synthesis of polycyclic N-heterocycles under electrochemical external oxidant-free conditions. The extent of the sequential electrochemical oxidative aromatization can be regulated with the assistance of redox mediators.
- Wang, Qiang,Yuan, Ting,Liu, Qiang,Xu, Yong,Xie, Guanqun,Lv, Xin,Ding, Shujiang,Wang, Xiaoxia,Li, Chen
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supporting information
p. 8398 - 8401
(2019/07/22)
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- Pyrrolo[2,1-a]isoquinoline derivatives via 1,3-dipolar cycloaddition of isoquinolinium N-ylides (II)
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The reaction of N-isoquinolinium bromides 3 with acrylonitrile and crotononitrile as activated olefinic dipolarophiles gave in the presence of triethylamine and the oxidant tertrakis-pyridinecobalt(II) dichromate (TPCD), in DMF at 90 °C, 1-cyanopyrrolo[2,
- Georgescu, Emilian,Dumitrescu, Denisa,Georgescu, Florentina,Draghici, Constantin,Dumitrascu, Florea
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scheme or table
p. 691 - 695
(2012/04/04)
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- 1,2-Dihydroisoquinoline-N-Acetic Acid Derivatives as New Carriers for Specific Brain Delivery I: Synthesis and Estimation of Oxidation Kinetics Using Multivariate Calibration Method
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In order to overcome the slow oxidation of 1,2-dihydro-N-alkylisoquinoline, 1,2-dihydroisoquinoline-N-acetic acid derivatives (3 b-d) were designed and synthesized as new chemical delivery systems (CDS) for the brain. Molecular orbital calculations for th
- Mahmoud, Sahar,Aboul-Fadl, Tarek,Sheha, Mahmoud,Farag, Hassan,Mouhamed, Abdel-Maaboud I.
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p. 573 - 584
(2007/10/03)
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- Study of the reactivity of substituted phthalic acids and anhydrides in condensation reactions with N-carboxymethylpyridinium salts and the synthesis of novel N-(1H-indene-1,3(2H)-dion-2-yl)pyridinium betaines
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Reaction of substituted phthalic acids or their anhydrides (including pyromellitic dianhydride) with salts of N-carboxymethylpyridinium and substituted N-carboxymethylpyridinium in the presence of acetic anhydride and triethylamine in acetonitrile or acetic acid solutions gave a series of novel N-(1H-indene-1,3(2H)-dion-2-yl)pyridinium betaines. Electron acceptor substitutents in the phthaloyl and pyridine rings were found to increase and electron donor substituents - to decrease the reactivity. 1999 Kluwer Academic/Plenum Publishers.
- Neilands,Shebenina,Pukitis
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p. 1443 - 1450
(2007/10/03)
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- 2-Methylpyridinium Salts as 1,4-Dinucleophiles. II. Westphal Condensation with Substituted Pyridinium Substrates
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Condensation of α-methylpyridinium, quinolinium and isoquinolinium salts with 1,2-dicarbonyls in the presence of base, yielded quinolizinium derivatives.In an analogous process, α-benzyl derivatives produced 2,3-dihydroindolizin-2-ones by intramolecular c
- Ezquerra, J.,Alvarez-Builla, J.
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p. 1151 - 1157
(2007/10/02)
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- SYNTHESIS AND STRUCTURAL STUDY ON Α-SUBSTITUED-1-STYRYLPYRIDINIUM SALTS. REINVESTIGATION OF KROHNKE CONDENSATION
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Kroehnke condensation of several cycloimmonium salts with p-dimethylaminobenzaldehyde has been studied.X-Ray diffraction, IR and Raman spectra, 1H- and 13C-NMR and UV spectra of the products are discussed, being compared, when necessary, with the starting pyridinium salts.All compounds showed the Z configuration, corresponding to the more stable structure, except one, in which steric factors were predominant.
- Alvarez-Builla, J.,Novella, J. L.,Galvez, E.,Smith, P.,Florencio, F.,et al.
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p. 699 - 708
(2007/10/02)
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- THE SYNTHESIS OF SOME ALCOHOLS DERIVED FROM 1,2,3,4-TETRAHYDROISOQUINOLINE AND FROM 1,2,3,4-TETRAHYDROQUINOLINE
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Reduction of ethyl ester of ω-(1,2,3,4-tetrahydro-2-isoquinolyl)alkanoic acids IVa-e by means of LiAlH4 was used for the preparation of corresponding primary alcohols Ia-e. 6-(1,2,3,4-tetrahydro-2-isoquinolyl)-1-hexanol (Ie) was also obtained on reduction of ester amide VII.Reduction of 2-(2-hydroxypropanoyl)-1,2,3,4-tetrahydroisoquinoline (V) with LiAlH4 gave secondary alcohol II; in the quinoline series alcohol IIIa was obtained in a similar manner by reduction of ethyl 3-(1,2,3,4-tetrahydro-1-quinolyl)propanoate (IIIb).
- Ferles, Miloslav,Silhankova, Alexandra,Kafka, Stanislav,Taufmann, Petr,Motacek, Tomas
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p. 1759 - 1764
(2007/10/02)
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- Preparation of Tetrahydroindolizines from Pyridinuim and Isoquinolinium Ylides
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Carbonyl- and nitrile-stabilised pyridinium and cyclic azonium methylides condense with chalcones to form tetrahydroindolizines and analogous fused pyrrolidines.The stereochemistry is illuminated by 13C and 1H n.m.r. spectroscopy.Several incorrect literature structures are rectified.
- Katritzky, Alan R.,Grzeskowiak, Nicholas E.,Alvarez-Builla, Julio
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p. 1180 - 1185
(2007/10/02)
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