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The Norcaradiene Problem
Author(s) -
Maier G.
Publication year - 1967
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.196704021
Subject(s) - cycloheptatriene , tautomer , ring (chemistry) , chemistry , benzene , valence (chemistry) , stereochemistry , computational chemistry , organic chemistry
Abstract Compounds having the norcaradiene structure are stable if one of the double bonds of the norcaradiene also belongs to a benzene ring or if C atoms 1 and 6 are fixed in position by a bridge. A similar effect that favors the norcaradiene form is produced by the incorporation of nitrogen atoms in positions 3 and 4. Cycloheptatriene and most of the simply substituted tropilidenes exist exclusively in the monocyclic triene form. It has been possible in some cases to detect a valence‐tautomeric equilibrium between the norcaradiene and the cycloheptatriene ring system. Non‐classical stabilization of compounds having norcaradiene or cycloheptatriene structure in the sence of a pseudoaromatic “homobenzene” is only very slight, if it occurs at all.