- Synthesis of highly functionalized polycyclic quinoxaline derivatives using visible-light photoredox catalysis
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A mild and facile method for preparing highly functionalized pyrrolo[1,2-a]quinoxalines and other nitrogenrich heterocycles, each containing a quinoxaline core or an analogue thereof, has been developed. The novel method features a visible-light-induced decarboxylative radical coupling of ortho-substituted arylisocyanides and radicals generated from phenyliodine(III) dicarboxylate reagents and exhibits excellent functional group compatibility. A wide range of quinoxaline heterocycles have been prepared. Finally, a telescoped preparation of these polycyclic compounds by integration of the in-line isocyanide formation and photochemical cyclization has been established in a three-step continuousflow system.
- He, Zhi,Bae, Minwoo,Wu, Jie,Jamison, Timothy F.
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supporting information
p. 14451 - 14455
(2015/02/19)
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- Building heterocyclic systems with RC(OR)2+ carbocations in recyclable bronsted acidic ionic liquids: Facile synthesis of 1-substituted 1H-1,2,3,4-tetrazoles, benzazoles and other ring systems with CH(OEt)3 and EtC(OEt)3 in [EtNH 3][NO3] and [PMIM(SO3H)][OTf]
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1-Aryl/alkyl-1H-1,2,3,4-tetrazoles can conveniently be synthesized in one-pot reactions from the corresponding amines by reaction with TMSN 3 and CH(OEt)3 using the readily available, recyclable, Bronsted acidic ionic liquids [EtNH3][NO3] IL-1 and [PMIM(SO3H)][OTf] IL-2 under mild conditions in high yields. Based on comparative reactions, whereas both ILs are excellent promoters, reactions are completed with shorter reaction times and in higher yields with IL-2. Among 24 examples provided, identical products were obtained via the two ILs, except in the case of 2-aminobenzoic acid where tetrazole was formed with IL-2 and 2-ethylquinazolin-4(3H)-one was formed with IL-1. By leaving out TMS-N 3 from the reaction, the in-situ formed CH(OEt)2 + and EtC(OEt)2+ (via their corresponding orthoesters) react under sonication with o-phenylenediamine bearing various substituents, o-aminothiophenol and o-aminophenol to form a wide array of benzazoles (benzimidazole, benzothiazole and benzoxazole) and quinazolin-4(3H)-one in high yields (18 examples). The two ILs reacted differently in reaction with 2-aminobenzamide, whereas quinazolin-4(3H)one was formed with IL-2/CH(OEt)3, the "unexpected" N-ethylquinazolin-4(3H)one was isolated with IL-1/CH(OEt)3. The latter was also formed from 2-aminobenzoic acid in IL-1/CH(OEt)3. Mechanistic implications are addressed. The reported protocols enable rapid assembly of a host of heterocyclic systems in high yields with the added advantage of recycling and re-use of the ILs.
- Aridoss, Gopalakrishnan,Laali, Kenneth K.
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experimental part
p. 2827 - 2835
(2011/06/23)
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- Application of the Pictet-Spengler reaction to aryl amine substrates linked to deactivated aromatic heterosystems
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Three new substrates with an aryl amine moiety attached to quinoxalines, triazoles and tetrazoles either via C or N have been used for the Pictet-Spengler reaction. The substrates have been designed by applying the concept of 'aryl amine attached to a dea
- Saha,Sharma,Sawant,Kundu
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p. 8676 - 8684
(2008/12/21)
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- SYNTHESIS AND PROPERTIES OF PHENYLENEBIS-1H-TETRAZOLES
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Heterocyclization of m- and p-phenylenediamines with orthoformic ester and sodium azide has given phenylenebis-1H-tetrazoles.Under these conditions, o-phenylenediamine gives benzimidazole. o-, m-, and p-Phenylenebis-1H-tetrazoles were also obtained from the nitroanilines via the intermediate nitro- and aminophenyltetrazoles.The reactions of the bistetrazoles examined were basic hydrolysis, aminomethylation, and complex formation with copper salts.
- Gaponik, P. N.,Karavai, V. P.,Davshko, I. E.,Degtyarik, M. M.,Bogatikov, A. N.
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p. 1274 - 1278
(2007/10/02)
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