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The Reaction of 3‐Formylchromone with ortho ‐Substituted Anilines. Preparation of a Tetraaza [14]annulene
Author(s) -
Sigg Ivo,
Haas Georges,
Winkler Tammo
Publication year - 1982
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.19820650128
Subject(s) - chemistry , annulene , chromone , dehydrogenation , diphenylamine , yield (engineering) , medicinal chemistry , ethanol , mass spectrum , proton nmr , stereochemistry , organic chemistry , catalysis , ion , materials science , metallurgy
The reactions of 3‐formylchromone ( 1 ) with 1, 2‐phenylenediamine, 2‐amino‐diphenylamine and 2‐aminophenol were reinvestigated and shown to yield 1, 8‐dihydro‐6, 13‐di (2‐hydroxybenzoyl)‐dibenzo [ b , i ]‐l, 4, 8, 11‐tetraazacyclotetradeca‐ 4, 6, 11,13‐tetraene ( 7 ), 3‐[2‐(1‐phenyl)benzimidazolyl]chromone ( 10b ) and 3‐(2‐hydroxyphenyl)iminomethylchromone ( 4 ), respectively at variance with earlier reports. Compound 4 reacts with ethanol to give 2‐ethoxy‐3‐[(2‐hydroxyphenyl)‐aminomethylidene]chroman‐4‐one ( 5b ). Dehydrogenation of 7 produces 3‐(2‐benz‐imidazolyl)chromone ( 10a ), also at variance with earlier reports. The structures have been elucidated with the aid of NMR. and mass spectra. The reaction mechanism is discussed.