- Electron-deficient carbocations. Direct observation of α-carbonylmethyl cations by laser flash photolysis
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The 9-carbomethoxyfluoren-9-yl cation was generated under stable ion conditions and characterized by spectral data (visible/NMR spectroscopy) and product identification of the benzene and toluene trapping reactions. The laser flash excitation of methyl α-
- Johnston, Linda J.,Kwong, Patrick,Shelemay, Avshalom,Lee-Ruff, Edward
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p. 1664 - 1669
(2007/10/02)
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- The Protecting-Directing Role of the Trityl Group in Syntheses of Pyrrole Derivatives: Efficient Preparations of 1-H-Pyrrole-3-carboxylic Acid and 3-Acyl, 3-Amino, and 3-Bromo-1-tritylpyrroles
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Trifluoroacetylation, formylation, and bromination of 1-tritylpyrrile occur regioselectively at the 3-position in high yields.Quantitative hydrolysis of the 3-trifluoroacetyl derivative and removal of the trityl group from the resulting acid with sodium in liquid ammonia furnishes a new, short, high-yielding synthessis of the simple 1-H-pyrrole-3-carboxylic acid. 1-Tritylpyrrole-3-carboxylic acid has been converted efficiently into 3-aminopyrroles via Curtius rearrangement of the derived azide: 3-amino-1-tritylpyrrole appears to exist in solution exclusively as its imino-Δ4-pyrroline tautomer. 1-H-3-t-Butyloxycarbonylaminopyrrole udergoes trifluoroacetylation regioselectively at the 2-position.Metallation of 1-tritylpyrrole with butyl-lithium in hexamethylphosphoric triamide gives rise to the unexpected products 9-phenylfluorene, 1-methoxycarbonylpyrrole and methyl triphenylmethylacetate (after work-up of the lithio-intermediates with carbon dioxide and methylation of the resulting acids).
- Chadwick, Derek J.,Hodgson, Simon T.
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