Über den Abbau des Chlorophylls durch Alkali

Treibs, Alfred; Wiedemann, E.

doi:10.1002/jlac.19294710107

Cited by 32 publications

(4 citation statements)

References 12 publications

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“…Etioporphyrin 1 (51), 1,3,5,7-tetramethyl-2,6-diethyl-4,8-di-n-propylporphin (51), desoxo-phylloerythrin (51), methyl 1,4,5,8-tetramethylporphin-2,3,6,7-tetracarboxylate (53), and coproporphyrin 3 (35) had been made previously. Pyrophaeophorbide-a, phylloporphyrin (54), and phyllochlorin (55) were from H. Fischer's collection, the Chlorobium phaeophorbides (56,57) were from A. S. Holt's.…”

Section: The Reference Pyrroles and Their Relativementioning

confidence: 99%

The Analytical Reduction of Porphyrins to Pyrroles

Chapman¹,

Roomi²,

Morton³

et al. 1971

Can. J. Chem.

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When porphyrins or related pigments are reduced by HI-AcOH, their meso-substituents (R = H or alkyl) appear as a-CH2R groups in the resulting pyrroles. The identification of the pyrroles, as by g.l.p.c., defines and orders the meso-substituents flanking each pair of peripheral substituents in the porphyrin. If one meso-substituent differs from the others, all the substituents about the two adjacent pyrrole nuclei are then ordered.The pyrroles can be reductively alkylated in situ, and symmetry then reduces their number when the aldehyde used (R.CH0) corresponds to a bridge and its meso-substituent. This may simplify the pyrrole mixtures, identify meso-substituents, or make pyrroles distinguishable by g.1.p.c.The critical pyrrole -propionic acids are separable as methyl esters by g.1.p.c. Desoxophylloerythrin and pyrophaeophorbides (the latter first reduced with potassium borohydride) are reduced to cyclopenteno-pyrroles which reveal the isocyclic rings and the 5-substituents. The r.r.t.3 of relevant pyrroles are reported.La reduction des porphyrines et des pigments du mCme genre par HI-AcOH fait que les substituants mtso (R = H OLI alkyle) apparaissent sous forme de groupements CH2R en cc des pyrroles resultants. L'identification des pyrroles par c.p.l.g., par exemple, definit et classe les substituants meso qui se trouvent a cBte de chaque paire de substituants peripheriques dans la porphyrine. Si un des substituants meso differe des autres, tous les substituants autour des deux noyaux pyrroles adjacents sont alors clasds.L'alkylation reductive irz situ des pyrroles peut riduire par symitrie le nombre de pyrroles lorsque l'aldehyde utilise (R.CH0) correspond au pont et au substituant meso de la porphyrine initiale. Ceci peut simplifier le melange des pyrroles, identifier les substituant meso et differentier les pyrroles par c.p.1.g.Les acides critiques pyrrole -propioniques sont separables de leurs esters methyliques par c.p.1.g. La dCsoxophylloerythrine et les pyrophaephorbides (ces dernieres d'abord reduites par le borohydrure de potassium) sont reduites en cyclopenteno-pyrroles, ce qui revele les noyaux isocycliques et les substituants en 5. Les donnees t.r.r, des pyrroles correspondants sont rapportkes.

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Section: The Reference Pyrroles and Their Relativementioning

confidence: 99%

The Analytical Reduction of Porphyrins to Pyrroles

Chapman¹,

Roomi²,

Morton³

et al. 1971

Can. J. Chem.

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“…All previous methods applied to porphyrin reductions demonstrated little, if any, selectivity (Fuhrhop, 1975;Burns et al, 1988) with regard to which pyrrole subunit was reduced in the formation of the chlorin. The only unique regioselective reduction which has been affected utilized porphyrins with sterically congested substituents on adjacent methine bridges (Fischer and Balaz, 1942;Treibs and Wiedemann, 1929), thus rendering the neighboring pyrroles susceptible to unusual addition reactions. This principle was further developed by Woodward (1960) in one of the crucial stages of his Chl a synthesis.…”

Section: Resultsmentioning

confidence: 99%

Regioselective Photoreduction of Zinc(ii) Porphyrins to Give Chlorins

Iakovides

Simpson

Smith

1991

Photochem & Photobiology

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The ascorbic acid/organic base photoreduction of zinc(II) porphyrins was investigated. It was established that certain substituents can direct the photoreduction to the site of the macrocycle to which they are attached. For example, zinc(II) vinylporphyrins (8, 12, 16, 20) are photoreduced with cis stereochemistry on the ring bearing the vinyl group to give the corresponding chlorins. Zinc(II) acetylporphyrins (22, 24) were likewise reduced to chlorins such that cis-hydrogenation took place on the ring bearing the acetyl group. Zinc(II) formylporphyrins 33 also appear to reduce at the ring bearing the formyl group. When the zinc(II) acrylic porphyrin 28 was photoreduced, reduction did take place at the ring bearing the acrylic side chain, but migration of the acrylate double bond was very rapid, and the product isolated was the corresponding porphyrin propionate 30. Reduction of a zinc(II) porphyrin 35 bearing both a vinyl group and a nuclear carboxylic ester took place at the ring bearing the carboxylic ester. The reaction provides a general method for regioselective synthesis of chlorins from zinc(II) porphyrins without any evidence of formation of over-reduction products characteristic of many other procedures for formation of chlorins from porphyrin precursors.

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“…Surprisingly, the formation of a mono-wesö-substituted chlorin more closely related to the chlorophylls was reported as early as 1929. 42 Treatment of the phylloporphyrin 18 with sodium ethoxide at 185°C produced in good yield (20%) a chlorin to which structure 19 was assigned on the basis cooch3 C00CH3 18 19 of its uv-vis spectrum. This structure was proved correct 40 years later by X-ray crystallography.…”

Section: Chemical Reduction To Chlorinsmentioning

confidence: 99%

Synthesis and Stereochemistry of Hydroporphyrins

Scheer¹

1978

The Porphyrins

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Über den Abbau des Chlorophylls durch Alkali

Cited by 32 publications

References 12 publications

The Analytical Reduction of Porphyrins to Pyrroles

The Analytical Reduction of Porphyrins to Pyrroles

Regioselective Photoreduction of Zinc(ii) Porphyrins to Give Chlorins

Synthesis and Stereochemistry of Hydroporphyrins

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