- Reactions of 2-(pyrrol-1-yl)benzyl radicals and related species under flash vacuum pyrolysis conditions
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2-(Pyrrol-1-yl)phenoxyl, aminyl, thiophenoxyl and benzyl radicals 2a-2d, respectively, were generated in the gas-phase under flash vacuum pyrolysis conditions. In all cases except the phenoxyl, cyclisation took place providing acceptable synthetic routes to the fused heterocycles 11, 14 and 15, respectively. Only sigmatropic rearrangement products were isolated, in low yields, from the phenoxyl 2a. The pyrrolo[1,2-a]benzimidazole 11 adopts the 1H-tautomer exclusively in chloroform solution. Electrophilic substitution reactions of pyrrolo[2,1-b]benzothiophene 14 were studied, including protonation, deuterium exchange, Vilsmeier formylation and reaction with dimethyl acetylenedicarboxylate. 2-(2,5-Diarylpyrrol-1-yl)thiophenoxyl, phenoxyl and aminyl radicals 23a-f, were also generated in the gas-phase under similar conditions. The thiophenoxyls 23a/b gave extremely complex pyrolysate mixtures in which primary cyclisation products were formed by attack of the radical at the pyrrrole ring and attack at the ipso-, ortho- and meta- positions of the aryl ring. Secondary pyrolysis products were obtained by specific sigmatropic shifts of the N-aryl group. The 2,5-di(thien-2-yl)thiophenoxyl radical 23c gave the pyrrolobenzothiazole 31c as the only cyclisation product in low yield. FVP of the phenoxyl and aminyl radical generators 26d and 26f, respectively, gave 3-arylpyrrolo[1,2-f]phenanthridines 46d and 46f, respectively, by a hydrogen transfer-cyclisation mechanism.
- Cadogan,Clark, Bernard A. J.,Ford, Daniel,MacDonald, Ranald J.,MacPherson, Andrew D.,McNab, Hamish,Nicolson, Iain S.,Reed, David,Sommerville, Craig C.
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supporting information; experimental part
p. 5173 - 5183
(2010/04/03)
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- Generation and contrasting gas-phase reactivity of 2-(2-alkenylpyrrol-1-yl) phenoxyl and thiophenoxyl radicals
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The pyrrolylacrylates 9 and 10 were synthesised and subjected to flash vacuum pyrolysis (FVP) at 650-700 °C to generate the radicals 11 and 18, respectively. The phenoxyl 11 underwent hydrogen capture to give a mixture of the phenol 12 and the pyrrolobenzoxazine 13 in low yields, which were also obtained by a Wittig reaction of the 2-formylpyrrole 14. The thiophenoxyl 18 gave a single major product in 41% yield which was identified as the pyrrolo[1,2-a]quinoline 17 by a sequence of NMR experiments. A mechanism for the formation of 17 by a rearrangement-sulfur extrusion sequence is proposed. The Royal Society of Chemistry 2006.
- Cadogan,Hewage, Chandralal M.,McNab, Hamish,MacPherson, Andrew D.,Nicolson, Iain S.,Reed, David,Sadler, Ian H.
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p. 2446 - 2451
(2008/03/11)
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- Synthesis of 4H-Pyrrolobenzothiazines and 3-(Methylthio)oxindoles
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The Pummerer reaction was carried out with α-acylsulfides and phenyl iodosyl bis(trifluoroacetate) instead of α-acylsulfoxides to prepare 4H-pyrrolobenzothiazines and 3-(methylthio)oxindoles.
- Wang, Huey-Min,Lin, Meng-Chiao,Chen, Ling-Ching
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p. 217 - 220
(2007/10/02)
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- SYNTHESIS OF 4H-PYRROLO-BENZOTHIAZINES AND N-METHYL-1,3,4,5-TETRAHYDRO-2H-3-BENZAZEPIN-2-ONES
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Pummerer-type reaction was carried out with α-acyl sulfides and phenyliodine(III)bis(trifluoroacetate) instead of α-acyl sulfoxides to prepare 4H-pyrrolobenzothiazines and N-methyl-1,3,4,5-tetrahydro-2H-3-benzazepin-2-ones.
- Wang, Huey-Min,Lin, Meng-Chiao,Chen, Ling-Ching
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p. 1519 - 1526
(2007/10/02)
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- A Comparative Molecular Field Analysis Model for 6-Arylpyrrolobenzothiazepines Binding Selectively to the Mitochondrial Benzodiazepine Receptor
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A series of 42 6-arylpyrrolobenzothiazepines, which we have recently described as selective ligands of the mitochondrial benzodiazepine receptor (MBR) (Fiorini I.; et al.J.Med.Chem. 1994, 37, 1427-1438), have been investigated using the compar
- Greco, Giovanni,Novellino, Ettore,Fiorini, Isabella,Nacci, Vito,Campiani, Giuseppe,et al.
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p. 4100 - 4108
(2007/10/02)
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- Intramolecular Capture of Pummerer Rearrangement Intermediates. I. Synthesis of Pyrrolobenzothiazines
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Treatment of 1-(2-alkylsulfinylphenyl)pyrroles with trifluoroacetic acid in refluxing toluene gives 4-substituted pyrrolobenzothiazines in good yield when the alkyl group bears an electron withdrawing substituent on the α-carbon.In the absence
- Bates, Dallas K.,Winters, R. Thomas,Burnell, A. Sell
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p. 695 - 699
(2007/10/02)
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