Syntheses of Bile Pigments. Part 17. Synthesis of a non-racemizable urobilin derivative
| Autor: | Lubomir Floch, Fredy Nydegger, C. Kratky, Albert Gossauer |
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| Rok vydání: | 1994 |
| Předmět: |
Stereochemistry
Organic Chemistry Enantioselective synthesis Absolute configuration Chromophore Biochemistry Catalysis Inorganic Chemistry chemistry.chemical_compound chemistry Drug Discovery Physical and Theoretical Chemistry Enantiomer Chirality (chemistry) Derivative (chemistry) Cotton effect Urobilin |
| Zdroj: | Helvetica Chimica Acta. 77:445-452 |
| ISSN: | 1522-2675 0018-019X |
| DOI: | 10.1002/hlca.19940770205 |
| Popis: | The optically active urobilin model compound 7 was synthesized, in which Me groups instead of H-atoms are bound to the asymmetric centers, thus preventing loss of chirality by tautomerization. The key intermediate of the eleven-step synthesis of 7 is the 1,4,5,10-tetrahydro-10-hydroxy-1-oxo-11H-dipyrrin-9-carboxylate rac-2, which could be resolved into enantiomers by fractional crystallization of the corresponding methyl N-[1-(naphth-1-yl)ethyl]carbamates 3 and 4. The absolute configuration of enantiomerically pure (−)-2 was determined by X-ray diffraction analysis of its camphor-10-sulfonate 5. As the CD spectrum of the urobilin analogue 7 obtained from (−)-(R)-2 displays a positive Cotton effect, the present results prove, in connection with previous work, that substitution of Me groups for the H-atoms bound to the asymmetric centers of a chiral urobilin chromophore do not influence the relationship between absolute configuration of the latter and its helicity. |
| Databáze: | OpenAIRE |
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