Über Enolderivate der Chlorophyllreihe. Darstellung von 13²,17³‐Cyclophäophorbid‐enolen. Vorläufige Mitteilung

Abstract

Enol derivatives in the chlorophyll series. Preparationof 13~,173-~yclopheophorbide enole. Summary. 13~,173-Cyclopheophorbide enols have been prepared as model systems for studying the effect of ring E enolization upon the properties of chlorophyll derivatives. Die Moglichkeit, dass im Chlorophyll a (1) und in seinen Derivaten, das @-Ketoestersystem des isocyclischen Ringes in die Enolform iibergehen kann, ist die Ursache einer Reihe von Eigenheiten im chemischen Vei halten dieses Verbindungstyps [Z]. Solche Enole bzw. entsprechende Enolate werden als Zwischenprodukte beim Molisch'schen Pliasentest 131, b i oxydativen Veranderungen des isocyclischen Ringes :2a], beim leicht erfolgenden H/D-Austausch an diesem Ring L5j [6j sowie bei der konfigurativen Aquilibrierung dcs @-Ketocstersystems [6] angenommen. Das Keto/ Enol-Gleichgewicht liegt nacli Refunden insbesondere von Kutz et ul. 'Zb] [6] bei 5)

Synthesis and Stereochemistry of Hydroporphyrins

“…124 On the other hand, the s-cis ß-diketone 45 is enolized even in the absence of chelating metal ions. 188 Spectroscopic differences observed between the natural 7\9>-transoidchlorins and their cisoid isomers are a further Fig. 3.…”

“…145 Diketo derivatives like 45 form more stable complexes of the same type. 188 The latter diketones are obtained by intra molecular Dieckmann condensation of the 7-propionic ester with the 10-ester. Α Δ-9,10 structure has been suggested, too, for the product obtained by Vilsmeier-Haak formylation of Cu-pyromethylpheophorbide a.…”

On the sedimentary occurrence of chlorophyllone a

“…13 2 ,17 3 -cyclopheophorbide a enol was prepared from pyropheophorbide a methyl ester (6, Sigma, 95%) according to published methods (Falk et al, 1975;Ma and Dolphin, 1996;Ocampo et al, 2000), using sodium bis(trimethylsilyl) amide (Fluka, 1 M in THF) and sodium phosphate (Aldrich, 98%).…”

Risk Management by Organisms of the Phototoxicity of Chlorophylls

“…35,36 The derivatives have an exo-seven-membered ring formed by the Claisen-type condensation of the peripheral functional groups in the chlorin π-system of Chls-a/b: 13-COCH and 17-CH 2 CH 2 COO-phytyl. 37 We cultured a series of phycophagic protists and a specific unicellular alga as their food, and in an analysis of the pigment extracts of the cultures, we found CPEs to be the sole major chlorophyll derivatives. 35,36 Significantly, we found that CPEs are essentially nonfluorescent in solution (Φ F < 0.002 for cPPB-aE).…”