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Synthesis and structural assignment of 2,4′‐disubstituted benzylidenefluorenes and 4′‐substituted benzylidene‐1‐azafluorenes
Author(s) -
Annunziata Rita,
Molteni Valentina,
Raimondi Laura
Publication year - 1998
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199807)36:7<520::aid-omr327>3.0.co;2-7
Subject(s) - chemistry , substituent , isomerization , ring (chemistry) , lone pair , stereochemistry , electronic effect , group (periodic table) , computational chemistry , molecule , steric effects , organic chemistry , catalysis
In the course of a study aimed at the investigation of edge‐to‐face arene–arene interactions, substituted benzylidenefluorenes 8 – 16 and benzylidene‐1‐azafluorenes 20 – 24 were synthesized as mixtures of E – Z ‐isomers. The full structural assignment of these compounds, performed by 2D NMR experiments, is described together with a study of their E – Z isomerization under equilibrating conditions. For compounds 8 – 16 no correlation was observed between the electron‐donating or electron‐withdrawing nature of the substituent groups and the E / Z equilibrium ratios. In the case of 20 – 24 the predominance of the E ‐isomers seems to depend exclusively on the N‐lone pair–benzylidene ring electronic repulsion rather than on the nature of the para substituent on the aromatic ring. © 1998 John Wiley & Sons, Ltd.