Pyrrole oxidation

Pyrrole oxidizes in air to red or black pigments of uncertain composition. More usehil is the preparation of 2-oxo-A -pyrrolines, which is best carried out by oxidation of the appropriate pyrrole with in pyridine (37), eg, 3,5-dimethyl-ethyl-3-pyrrolin-2-one [4030-24-4] from... 

Nicotine Resolution of racemates N-Demethylation, pyrrole oxidation N-Dealkylation, pyrrole oxidation, iminium formation... 

St. Clair MB, Amamath V, Moody MA, et al. 1988. Pyrrole oxidation and protein cross-linking as necessary steps in the development of gamma-diketone neuropathy. Chem Res Toxicol 1 179-185. 

Electrooxidation of the pyrrole unit results in the formation of a pyrrole polymer that coats the electrode surface as it is formed. The amount of polymer deposited can be controlled by the number of CV cycles into the pyrrole oxidation wave. With 30, thick polymer layers give broad CV waves in the quinone voltage region, but thinner layers produce a well-resolved wave for the quinone 0/—1 reduction, which is reasonably stable when the electrodes are placed into fresh electrolyte solution with no 30. As in solution, addition of different urea derivatives causes this wave to shift positive. The relative magnitude of the shifts mirror that seen in solution. Furthermore, the 2 moves back to the original potential when the derivatized electrode is put back into a blank solution containing no urea. 

Meso-ionic compounds, 19, 1 Metal catalysts, action on pyridines, 2, 179 Monoazaindoles, 9, 27 Monocyclic pyrroles, oxidation, of, 15, 67 Monocyclic sullur-conlaining pyrones, 8, 219 Mononuclear heterocyclic rearrangements, 29, 141... 

Pure individual porphyrins such as (4)-(7) can, however, be synthesized using dipyrroles, and these approaches will be briefly discussed later in this section. If two dipyrrole units (8) and (9) with an appropriate future meso-carbon are reacted together with the intention of preparing porphyrin (10), there is actually a maximum of three possible products, (10) (12) (Scheme 3). This is because the two dipyrroles can either react with themselves, or (as required) with each other. If the dipyrroles do not possess attached (future) meso-carbon atoms (e.g., (13) and (14)) and also bear an unsymmetrical arrangement of substituents (indicated by the A and B labels on each pyrrole— oxidation levels, i.e., dipyrromethene or dipyrromethane, not defined), even greater mixtures can occur—in this case, porphyrins (15)-(20) (Scheme 4). Such symmetry problems are common with all so-called [2 + 2] syntheses. However, if a porphyrin synthesis involving two dipyrroles is to be attempted, the symmetry problems can often be overcome if one of the two dipyrroles is symmetrical about its interpyrrolic (5-) carbon atom (e.g., synthesis of (6) from (21) and (22), Scheme 5). 

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