- On the Chemistry of Pyrrole Pigments. XXXV: A Reversible Regioselective Addition to Bilatrienes-abc
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Using spectroscopic methods (UV-VIS, 1H-NMR) the reversible addition of donors (alcohols, amines, thiols, HCN, bisulfit and C-H acidic compounds) to bilatrienes-abc was investigated.This equilibrium is in close analogy to the addition of donors to a carbonyl group (as was deduced from thermodynamic and kinetic measurements) and is also the basis for understanding the photochemical isomerization of bilatrienes-abc in the adsorbed state.Based thereon a recipe for the isomerization of bilatrienes-abc in homogeneous phase giving high yields of the (E,Z,Z)-diastereomer is presented: in addition the (E,Z,E)-diastereomer of aetiobiliverdin-IV-γ was isolated and characterized for the first time.A model compound representing the intramolecular addition of a donor attached to a side chain (mimicking a peptide unit) was synthesized and studied with respect to its photochemical behaviour. - Keywords: Bilatrienes-abc; Photoisomerization; Reversible Addition
- Falk, Heinz,Mueller, Norbert,Schlederer, Thomas
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- Synthesis of Unsymmetric Bile Pigments: Mesobilirubin-VIIIα, 17-Desvinyl-17-ethyl-bilirubin-VIIIα and 12-Despropionic Acid-12-ethyl-mesobilirubin-XIIIα
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The unnatural bile pigments 17-desvinyl-17-ethylbilirubin-VIIIα, mesobilirubin-VIIIα and 12-despropionic acid-12-ethyl mesobilirubin-XIIIα were synthesized via (1) "reverse scrambling" of bilirubin-XIIIα or mesobilirubin-IXα with mesobilirubin-IVα or etiobilirubin-IVγ or (2) following coupling of xanthobilirubic acid methyl ester with ψ-xanthobilirubic acid methyl ester, or coupling of xanthobilirubic acid methyl ester with kryptopyrromethenone.
- Trull, Francesc R.,Lightner, David A.
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p. 1227 - 1230
(2007/10/02)
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