- Studies on the mechanism of the Carr-Price blue colour reaction
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The reaction of retinoids (retinol, retinyl acetate and anhydroretinol) with Bronsted acids was studied as a model system for the Carr-Price reaction. The anhydroretinylic cation was characterised by VIS and 2D NMR spectroscopy, including an estimate of t
- Kildahl-Andersen, Geir,Naess, Stine Nalum,Aslaksen, Petter B.,Anthonsen, Thorleif,Liaaen-Jensen, Synnove
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- Stereocontrolled synthesis of all-(E)- and (8Z)-anhydroretinol
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Convergent syntheses of hexaenes anhydroretinol and its (8Z)-isomer are described. Despite the mild reaction conditions for the final step in both cases, a Stille coupling reaction between trienyl triflates and trienyl stannanes, the stereochemical integr
- Alvarez, Rosana,Iglesias, Beatriz,Lopez, Susana,De Lera, Angel R.
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p. 5659 - 5662
(2007/10/03)
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- Intramolecular Diels-Alder reactions of the retinoid side chain
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Retinyl propynyl ether (RPE) undergoes an intramolecular Diels-Alder reaction to form a tetrahydroisobenzofuran derivative by addition of the alkyne group at positions 11 and 14 of the retinoid side chain. The Diels-Alder product can be isolated after RPE has been heated in refluxing ethanol. The Diels-Alder reaction also occurs very slowly in the solid state at low temperatures. The tetrahydroisobenzofurans is readily dehydrogenated to an aromatic retinoid, a 1,3-dihydroisobenzofuran. 2-Butynyl and 2-propenyl retinyl ethers undergo intramolecular cyclization to similar Diels-Alder products that can be isolated in yields of 50-60% after the ethers have been heated in refluxing toluene.
- Shealy, Y. Fulmer,Riordan, James M.,Frye, Jerry L.,Campbell, Sheila R.
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p. 405 - 424
(2007/10/03)
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- Iron(III)Porphinate/H2O2-Mediated Conversion of All-(E)-Retinol
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The reaction of hydrogen peroxide with all-(E)-retinol (1) catalyzed by (meso-tetraphenylporphinato)iron(III) led to the formation of 4-hydroxyretinol (2), 4-oxoretinol (3), 5,8-epoxyretinol (4), 5,6-epoxyretinol (5), 3-dehydroretinol (6), all-(E)- and 12-(Z)-retroretinol (7/7a) as well as all-(E)- and 12-(Z)-anhydroretinol (8/8a) as major non-volatile products.The conversion products were characterized by comparison of their chromatographic (HPLC) and spectroscopic data (UV; MS; 1H and 13C NMR) with those of synthesized reference compounds.The observed product formation supports the hypothesis of a C4 centered radical as the key intermediate of all-(E)-retinol conversion. - Keywords: 5,6- and 5,8-Epoxyretinol, 4-Hydroxyretinol, 4-Oxoretinol, Retinol Conversion
- Waldmann, Doris,Koenig, Thorsten,Schreier, Peter
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p. 589 - 594
(2007/10/02)
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- Ionic Photodissociation of Polyenes via a Highly Polarized Singlet Excited State
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Several polyene acetates and polyene methyl ether were prepared.Upon direct excitation these polyenes undergo ionic photodissociation from their singlet excited states.Triplet-sensitization experiments on these polyenes revealed that the ionic photodissociation process is restricted to singlet excited states.The rationale put forward is that the polyene chromophore undergoes charge separation/polarization in the singlet excited state, which leads to ionic photodissociation.
- Reddy, A. Mahipal,Rao, V. Jayathirtha
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p. 6727 - 6731
(2007/10/02)
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- REGIOSELECTIVE PHOTOISOMERISATION OF RETINOLACETATE
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Regioselective photoisomerisation of retinolacetate undergoing at tri-substituted double bonds upon singlet and triplet excitation and its ionic photodissociation process originating from singlet excited state is reported.
- Rao, V. Jayathirtha,Bhalerao, U. T.
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p. 3441 - 3444
(2007/10/02)
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