- Chemo- and regioselectivity in the reactions of polyfunctional pyrroles
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The chemo- and regioselectivity of the reduction, oxidation and Wittig reaction of polyfunctional pyrroles, containing a variety of reactive centres was investigated. The reaction of 3,5-dichloropyrrole-2,4-dicarboxaldehydes with potassium permanganate leads to regioselective oxidation of the 2-formyl group, while the Wittig reaction with 1 equiv of a triphenylphosphorane produced the 2-alkenyl substituted pyrroles. The chemo- and regioselectivity of the reactions of polyfunctional pyrroles, containing a variety of reactive centres is described. Regioselective reduction, oxidation or Wittig reactions give a range of pyrroles suitable for further synthetic transformations.
- Marth, Gabriella,Anderson, Rosaleen J.,Thompson, Barry G.,Ashton, Mark,Groundwater, Paul W.
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experimental part
p. 6113 - 6120
(2010/09/11)
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- LITHIATION OF THE DIMER OF 3-BROMO-6-DIMETHYLAMINO-1-AZAFULVENE. EFFICACIOUS SYNTHESIS OF 4-MONO- AND 4,5-DISUBSTITUTED PYRROLE-2-CARBOXALDEHYDES.
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The dimer 1a of 3-bromo-6-dimethylamino-1-azafulvene, is shown to function as a formal equivalent of 4-lithio- or 4,5-dilithiopyrrole-2-carboxaldehyde and consequently it is a progenitor, par excellence, of 4-mono- and 4,5-disubstituted pyrrole-2-carboxaldehydes.
- Muchowski, Joseph M.,Hess, Petr
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p. 3215 - 3218
(2007/10/02)
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- Pyrrole chemistry. XXI. Synthetic approaches to cyanopyrroles
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The Vilsmeier-Haack reaction with pyrrole and 1-methylpyrrole has been modified to provide a direct synthesis of the corresponding 2-nitriles.Chlorosulfonyl isocyanate may be used to prepare the some compounds, but less satisfactorily.The latter reagent does enable the synthesis of pyrrole-2,4-dicarbonitrile in one step.The dinitrile may be reduced to pyrrole-2,4-dicarboxaldehyde.
- Barnett, Graham H.,Anderson, Hugh J.,Loader, Charles, E.
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p. 409 - 411
(2007/10/02)
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- Pyrrole chemistry. XXII. A "one-pot" synthesis of some 4-acylpyrrole-2-carboxaldehydes from pyrrole
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The Vilsmeier-Haack intermediates formed from pyrrole and from 1-methylpyrrole may be acylated under normal Friedel-Crafts conditions.Hydrolytic work-up then gives 4-acylpyrrole-2-carboxaldehydes in good yield.The methoxide/methanol treatment of the 4-trichloroacetylated intermediate leads to methyl 2-formylpyrrole-4-carboxylate.These are all "one-pot" syntheses from pyrrole.The formyl group has been removed from several of the products thus affording some 3-acylpyrroles in two operations.
- Anderson, Hugh J.,Loader, Charles E.,Foster, Aidan
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p. 2527 - 2530
(2007/10/02)
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