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

✍ Scribed by Jan-Erik Damke; Lechosław Latos-Grażyński; Franz-Peter Montforts

• Book ID: 102257774
• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: German
• Weight: 385 KB
• Volume: 91
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200890023

✦ Synopsis

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.