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Methyl pyrrole-2-carboxylate bromination

Unsymmetrically substituted dipyrromethanes are obtained from n-unsubstitued pyrroles and fl(-(bromomethyl)pyiToIes in hot acetic acid within a few minutes. These reaction conditions are relatively mild and the o-unsubstituted pyrrole may even bear an electron withdrawing carboxylic ester function. It is still sufficiently nucleophilic to substitute bromine or acetoxy groups on an a-pyrrolic methyl group. Hetero atoms in this position are extremely reactive leaving groups since the a-pyrrolylmethenium( = azafulvenium ) cation formed as an intermediate is highly resonance-stabilized. [Pg.254]

Bromination of appropriate 5-acetoxymethyl pyrrole-2-carboxylic acids in ethanol-free chloroform at 10° affords previously inaccessible 5-bromo-5 -bromomethylpyrromethanes with alternating acetic acid (or methyl) and propionic acid side chains useful for copro- and uroporphyrin syntheses. [Pg.244]

See other pages where Methyl pyrrole-2-carboxylate bromination is mentioned: [Pg.332]    [Pg.215]    [Pg.368]    [Pg.215]    [Pg.368]    [Pg.159]    [Pg.332]    [Pg.261]    [Pg.283]    [Pg.328]    [Pg.331]    [Pg.766]    [Pg.7]    [Pg.2106]    [Pg.158]    [Pg.328]    [Pg.331]    [Pg.272]    [Pg.78]   
See also in sourсe #XX -- [ Pg.159 ]



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Methyl carboxylate

Pyrrole 2-carboxylate

Pyrrole bromination

Pyrrole, carboxylation

Pyrroles 3-methyl

Pyrroles carboxylation

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