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Unusual Loss of Substituents in the Course of Cyclization of Tetrahydrobilines to Dihydroporphyrins
Author(s) -
Damke JanErik,
LatosGrażyński Lechosław,
Montforts FranzPeter
Publication year - 2008
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200890023
Subject(s) - chemistry , substituent , stereochemistry , selectivity , position (finance) , medicinal chemistry , organic chemistry , catalysis , finance , economics
Abstract 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.