Unusual Loss of Substituents in the Course of Cyclization of Tetrahydrobilines to Dihydroporphyrins

Metallo‐tetrahydrobiline rac‐8 was prepared to investigate its cyclization directed to the formation of N‐confused chlorins. To achieve the site‐directed selectivity of the cyclization, the 2‐position of rac‐2 was activated by an electron‐withdrawing cyano function and its 1‐position was blocked by...

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Bibliographic Details
Published in:Helvetica chimica acta 2008-02, Vol.91 (2), p.177-186
Main Authors: Damke, Jan-Erik, Latos-Grażyński, Lechosław, Montforts, Franz-Peter
Format: Article
Language:English
Subjects:
Bilines
Bilines, tetrahydro
Chlorins
Cyclization reactions
dihydro
Porphyrins
Porphyrins, dihydro
tetrahydro
X-Ray crystallography
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Summary:Metallo‐tetrahydrobiline rac‐8 was prepared to investigate its cyclization directed to the formation of N‐confused chlorins. To achieve the site‐directed selectivity of the cyclization, the 2‐position of rac‐2 was activated by an electron‐withdrawing cyano function and its 1‐position was blocked by a methyl group. In spite of this provision, the cyclization occurred at the apparently blocked 1‐position with loss or migration of the methyl substituent.
ISSN:0018-019X
1522-2675
DOI:10.1002/hlca.200890023