Diels–Alder reactions of 3-(1H-tetrazol-5-yl)-nitrosoalkenes: synthesis of functionalized 5-(substituted)-1H-tetrazoles

Lopes, Susana M. M.; Palacios, Francisco; Lemos, Américo; Melo, Teresa M. V. D. Pinho e

doi:10.1016/j.tet.2011.09.051

Cited by 27 publications

(18 citation statements)

References 65 publications

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“…The formation of these products can be rationalized by considering the re‐aromatization of the initially formed Diels–Alder cycloadducts, bicyclic 1,2‐oxazines 3 (Y=O) or tetrahydropyridazines 3 (Y=NR′). (Scheme ) . Our studies on hetero‐Diels–Alder reactions of 3‐tetrazolyl‐nitrosoalkenes and 3‐tetrazolyl‐1,2‐diaza‐1,3‐butadienes demonstrated that this is an efficient approach to functionalized 5‐(substituted)‐1 H ‐tetrazoles, including pyrroles bearing the 1 H ‐tetrazol‐5‐yl substituent .…”

Section: Introductionmentioning

confidence: 84%

“…Flash column chromatography was performed with silica gel 60 as the stationary phase. 2‐Bromo‐1‐phenylethanone oxime ( 9 a ), 2‐bromo‐1‐( p ‐bromophenyl)ethanone oxime ( 9 b ), 2‐bromo‐1‐( p ‐nitrophenyl)ethanone oxime ( 9 c ), 2‐bromo‐1‐( p ‐fluorophenyl)ethanone oxime ( 9 d ), 1‐(1‐benzyl‐1 H ‐tetrazol‐5‐yl)‐2‐bromoethanone oxime ( 9 e ), 5‐ p ‐bromophenyldipyrromethane ( 5 b ), and 5‐phenyldipyrromethane ( 10 ) were prepared as described previously.…”

Section: Methodsmentioning

confidence: 99%

“…[13][14][15][16] Our studies on hetero-Diels-Alder reactions of 3-tetrazolyl-nitrosoalkenes and 3-tetrazolyl-1,2-diaza-1,3-butadienesd emonstratedt hat this is an efficient approach to functionalized 5-(substituted)-1H-tetrazoles, including pyrroles bearingt he 1H-tetrazol-5-yl substituent. [15,16] The alkylation of pyrrole via reactionw ith a-halooximes or a-halohydrazones is carried out in the presence of ab ase to ensure the generation of conjugated alkenes.However,there is alwaysthe question of whether ah etero-Diels-Alder reaction or ac onjugate 1,4-addition is taking place. Although the experimental evidencea vailablei ndicates that Diels-Alder cycloadditions are involved in the majority of cases,w er ecently demonstrated that 1-(p-bromophenyl)nitrosoethylene reacts with pyrrole to give two isomeric oximes via conjugatea ddition followed by re-aromatization of the pyrrole unit (e.g., 4a and 4b).…”

Section: Introductionmentioning

confidence: 99%

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Biological Evaluation of Dipyrromethanes in Cancer Cell Lines: Antiproliferative and Pro‐apoptotic Properties

et al. 2017

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Functionalized dipyrromethanes were synthesized by hetero-Diels-Alder reactions of nitroso- and azoalkenes and screened for their in vitro activity as anticancer agents. The studied dipyrromethanes were tested against leukemia and lymphoma cell lines, and showed GI values in the mid-micromolar range. The pro-apoptotic activities of two candidates, (E)-1-(2'-ethoxycarbonylhydrazono-1'-benzyl-1H-tetrazol-5-yl)-5,5'-diethyldipyrromethane and (E)-1-(2'-p-nitrophenyl-2'-hydroxyiminoethyl)-5-phenyldipyrromethane, and their effects on the cell cycle are described. The latter compound was found to decrease the S-phase cell population in a dose-dependent manner and to irreversibly block cells in the G /M phase.

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Section: Introductionmentioning

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biological Evaluation of Dipyrromethanes in Cancer Cell Lines: Antiproliferative and Pro‐apoptotic Properties

et al. 2017

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“…Oximes 4 were isolated as single stereoisomers, the expected outcome for the ring-opening reaction of bicyclic 1,2-oxazines (Scheme 1) [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Indoles 10 were isolated as single stereoisomer, the expected outcome for the ring-opening reaction of the corresponding cycloadducts. Evidence for the generation of the nitrosoalkenes 2 followed by DielsAlder reaction also comes from the reaction of a-bromooximes 1 with 3-methylindole to give 1,2-oxazines 11 (Scheme 3) [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Reactivity of 1-arylnitrosoethylenes towards indole derivatives

et al. 2016

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The reactivity of 1-arylnitrosoalkenes toward indole, 1-methylindole, and 3-methylindole is described. In contrast with the previously observed chemical behaviour of 1-(p-bromophenyl)nitrosoethylene towards pyrrole, the studied heterodienes reacted with indole and 1-methylindole to afford E-oximes via hetero-Diels-Alder reactions. The reaction with 3-methylindole also proceeds via cycloaddition giving the corresponding 1,2-oxazine. Quantum chemical calculations, at the DFT level, indicate that the energy barriers associated with the reactions between 1-(p-bromophenyl)nitrosoethylene and indole and its derivatives are similar to those observed for the reaction between this nitrosoalkene and pyrrole. However, the calculated energy of the theoretical Diels-Alder cycloadducts involving indole and pyrrole clearly suggests that the Diels-Alder reaction is privileged in the case of indole. Furthermore, in the case of the indole, the energy difference between reactants and products clearly favors the regiochemistry observed experimentally. Graphical abstract N H N H O N N H N HO Br Br

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ChemInform Abstract: Diels—Alder Reactions of 3‐(1H‐Tetrazol‐5‐yl)‐nitrosoalkenes: Synthesis of Functionalized 5‐(Substituted)‐1H‐tetrazoles.

et al. 2012

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Diels-Alder Reactions of 3-(1H-Tetrazol-5-yl)-nitrosoalkenes: Synthesis of Functionalized 5-(Substituted)-1H-tetrazoles. -Cycloaddition of in situ generated nitrosoalkene [from oxime (I)] with cyclic enol ethers, cyclopentadiene, phenoxyallene as well as electron-rich heterocycles provides access towards oxazine (IX), (XI), (XIII), (XV), (XVII) or their regioisomeric oxime structures, e.g. (III), bearing an N-protected tetrazole ring. The tetrazole ring can be deprotected by transfer hydrogenation. Reduction of the oxime structure and subsequent tetrazole deprotection provides access towards masked α-amino acid structures [cf. (VII)]. -(LOPES, S. M. M.; PALACIOS, F.; LEMOS, A.; PINHO E MELO*, T. M. V. D.; Tetrahedron 67 (2011) 46, 8902-8909, http://dx.doi.org/10.1016/j.tet.2011.09.051 ; Dep. Chem., Univ. Coimbra, P-3004 Coimbra, Port.; Eng.) -Mischke 12-124

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Diels–Alder reactions of 3-(1H-tetrazol-5-yl)-nitrosoalkenes: synthesis of functionalized 5-(substituted)-1H-tetrazoles

Cited by 27 publications

References 65 publications

Biological Evaluation of Dipyrromethanes in Cancer Cell Lines: Antiproliferative and Pro‐apoptotic Properties

Biological Evaluation of Dipyrromethanes in Cancer Cell Lines: Antiproliferative and Pro‐apoptotic Properties

Reactivity of 1-arylnitrosoethylenes towards indole derivatives

ChemInform Abstract: Diels—Alder Reactions of 3‐(1H‐Tetrazol‐5‐yl)‐nitrosoalkenes: Synthesis of Functionalized 5‐(Substituted)‐1H‐tetrazoles.

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